Reliable pistons

I never head anything good about GPM pistons from Italy except they were available and cheap. The best pistons for Norton Dominators for general use are still the English made pistons that you can find in boxes marked Hepolite, Heplex and Wellworthy. Since there is no demand for these pistons no one has ever made better or more modern ones than these.

The only place to find them is to call big old supply houses and dealers or luck onto them on ebay.

It is a lot of work, but if you keep removing and re-installing your pistons while filing the areas of your pistons down that show signs of scuffing and seizing, eventually they will have the right shape when they are hot......

This is not a practice without precedent, some early factory two-stroke race bikes were supposed to have new pistons "adjusted" in this manner after a re-bore.

if you try Russell Motors (020-7228-1714) they have Genuine BHB pistons in STD size. I'm not sure if they still have the rings and pins but you can maybe find some or use the GPM ones. BHB (in Twickenham) used to make pistons for the AMC factory. To be honest the GPM ones aren't that bad, you have probably had it bored too tight. I have then in my 99 and haven't had any problems at all. The trouble is everyone blames the pistons when they seize. Filing the pistons down where they are rubbing must be the best joke I've heard for a long time.

Geoffrey Myers said:

" Filing the pistons down where they are rubbing must be the best joke I've heard for a long time. "

I am glad to entertain you. If you want to read an entire book of "jokes" like that, then get a copy of the famous book on tuning British engines Tuning for Speed by P.E. Irving, it was the bible of tuning British engines for many years and tells you exactly what marks to look at on a piston and which to use a file on and how to do it.

Also, with it's early two stroke racers, Yamaha instructed owners to rev an engine with a fresh top end job until it seized, then take the top off and work on the pistons with a file.

You Johnny-come-lately, know-nothing twit.......

Previously wrote:

if you try Russell Motors (020-7228-1714) they have Genuine BHB pistons in STD size. I'm not sure if they still have the rings and pins but you can maybe find some or use the GPM ones. BHB (in Twickenham) used to make pistons for the AMC factory. To be honest the GPM ones aren't that bad, you have probably had it bored too tight. I have then in my 99 and haven't had any problems at all. The trouble is everyone blames the pistons when they seize. Filing the pistons down where they are rubbing must be the best joke I've heard for a long time.

Hi - My Norton Manxman 650 has standard BHB pistons from new and now they have lasted 30,000 miles plus and are still ok. But I am looking for plus 10 thou oversize, as in the Parts Manual it gives plus Sizes +10 +20+ 30 and that's the maximum they did. Yours - Anna J Dixon

It is amazing that Gandini pistons, made by manufacturers who supply OE pistons to mayor car manufacturers, are being called "low quality". The more so considering we (Nick Hopkins and myself) run our own private Nortons with them. My "family racing Commando" has done no end of racing miles on the first set of pistons, and neither we, nor our trade customers find these pistons problematic.

Resleeved cylinders, though not a problem in themselves, can suffer from poor fitting of the sleeves, too loose leading to bad heat transfer (result: seizure), too tight to distortion of the bore (result: seizure). Another popular fault is that modern engine repair shops disbelieve the Norton and/or piston manufacturers advice on clearance and tend to bore the cylinders to far tighter tolerances (result: seizure).

The advice on what some vintage Manxman had fitted originally, or what pistons were good forty years ago, does not help today's restorer at all. Pistons normally have a short shelf life- no dealer will voluntarily stock expensive items like pistons for decades-, so whatever Messieurs Hepworth and Grandage produced in 1964 in superb quality is of purely historical value today.

As usual, there are several possible reasons for the component failure (see above), but again as usual these are being ignored or denied. In this case perhaps understandably by people who may have made a mistake when they worked on that cylinder, and a part that can not answer back is therefore blamed for a failure that was most probably caused by poor workmanship.

Joe, when you say pistons have a short shelf life, do you mean that they 'go off' in storage such as is reported to have occurred with wartime production BSA pistons ?

I haven't come across this with sixty year old Wellworthys and Hepolites. The fact is that for many models, these original equipment components can still be found (at least if not too many of us are looking for them). These parts gave almost no trouble in their day (ignoring slotted pistons in 750 Commandos) and that is so unusual in a Norton engine that I wouldn't want to use something else where questions existed.

I have used GPMs without problems but I don't like fitting their cast oil control rings and in the singles world, their 'one blank fits all' policy has led to them having a reputation for being heavy. Re-balancing is not desirable if only the top end is off.

I would want to measure the engine in question before passing judgement and I'd suspect that the GPMs are not the problem here. However, I can't help regarding them as a less desirable replacement for a proven component.

Richard,

Being in the trade leads to (wrongly) thinking everybody knows the language spoken inside it- "shelf life" has nothing to do with the goods going "off", but means the period the goods are likely to be on your shelf before they sell. The "shelf life" of, say, a crankcase is most likely longer than that of a popular valve cover gasket.

I don't say the OE (Original Equipment) pistons caused problems. All I say is we have no problems whatsoever with the GPM pistons in Norton Twin engines, including those that are pursuaded to pump out considerably more power than they had originally. Or those that, as in our "family racer", are ridden much harder than the average road bike, with more power in the engine, for considerable mileages. In one three-day meeting I was timed on it for over 100 laps in training, amounting to over 500km (300 miles), and don't forget this bike has been going for over ten seasons under half a dozen different riders. Now if the GPM pistons survive that, plus give no trouble in the road engines my friend and engine tuner Rudi builds every day, why should I worry about them not being up to the job?

I do not deny the weight is different to Hepolites, but then we also had great differences in weight with Hepolites over the years. For re-balancing when only the top half is off, if you find the GPMs are heavier than your previous piston it is common practice to take some material out of the piston until it has the required weight. A +.040" Hepolite is also heavier than a +.020", quite apart from the variations Hepolites had over the years- you mention the "slotted" ones. Over the years I have bought up a lot of dealers inventories. I could show you the variations in Hepolite piston weights for Commandos in my stores. For some obscure reason one tends to find always the same side pistons, though (Commando 750 pistons are handed), so I have a lot of NOS (New Old Stock) Hepolites in +.020" and +.040", but NO PAIRS..... Otherwise I'd be quite happy to sell them off and be left with the GPMs.

Joe

Previously wrote:

Richard,

Being in the trade leads to (wrongly) thinking everybody knows the language spoken inside it- "shelf life" has nothing to do with the goods going "off", but means the period the goods are likely to be on your shelf before they sell. The "shelf life" of, say, a crankcase is most likely longer than that of a popular valve cover gasket.

I don't say the OE (Original Equipment) pistons caused problems. All I say is we have no problems whatsoever with the GPM pistons in Norton Twin engines, including those that are pursuaded to pump out considerably more power than they had originally. Or those that, as in our "family racer", are ridden much harder than the average road bike, with more power in the engine, for considerable mileages. In one three-day meeting I was timed on it for over 100 laps in training, amounting to over 500km (300 miles), and don't forget this bike has been going for over ten seasons under half a dozen different riders. Now if the GPM pistons survive that, plus give no trouble in the road engines my friend and engine tuner Rudi builds every day, why should I worry about them not being up to the job?

I do not deny the weight is different to Hepolites, but then we also had great differences in weight with Hepolites over the years. For re-balancing when only the top half is off, if you find the GPMs are heavier than your previous piston it is common practice to take some material out of the piston until it has the required weight. A +.040" Hepolite is also heavier than a +.020", quite apart from the variations Hepolites had over the years- you mention the "slotted" ones. Over the years I have bought up a lot of dealers inventories. I could show you the variations in Hepolite piston weights for Commandos in my stores. For some obscure reason one tends to find always the same side pistons, though (Commando 750 pistons are handed), so I have a lot of NOS (New Old Stock) Hepolites in +.020" and +.040", but NO PAIRS..... Otherwise I'd be quite happy to sell them off and be left with the GPMs.

Joe

Hello Joe, Since you are sat on a mountain of GPM Piston's in your warehouse you would not let anyone say anything bad about them would you? So as I am a marine engineer I will stick to BHB that was fitted by Norton Motorcycles at Bracebridge Street ? Yours Anna J Dixon

Anna,

I find that remark in bad taste and it is far off the mark.

Our "family racer" engine was built about ten years ago with GPM pistons (that it still runs on), my '68 Fastback about 15 years ago (ditto). The man who builds the best, i.e. most reliable and fastest Norton engines in Germany, Rudi Kolano, actually PREFERS GPM pistons to Hepolites, including for 850s, these being the only Commando pistons that are still available from AE Hepolite.

The fact that I had my very own engines built with GPM pistons YEARS before I "sat on a mountain of GPM Pistons in my warehouse"- remember I only bought Andover Norton in April 2007- speaks for itself. At that time I ran Norton Motors GmbH in Germany- as I do to date- and still had AE Hepolite pistons in stock for those customers who insisted on them. So I had an alternative. Had I thought the GPMs were no good, would I have used them in my own engines?

In the classic bike scene people often fondly imagine that certain original parts are better than today's offerings. I just read in another forum about the original Commando seats being so much better than what is in the market today, because their foam was far better. I could have told the author of that comment about the seat I had on my Commando Interstate I bought new in April 1977, and how I, much slimmer and lighter then, sat on the seat pan after only about 10.000 miles because this then "much superior foam" had already collapsed after a few months in 1977.....

As you don't know me you don't know I decline to sell substandart stuff to my customers. You also don't know I ride Nortons and for how many miles I have done it. Even before I owned Andover Norton I insisted on Genuine Andover Norton product for my customers. There were always cheaper alternatives- and are to date- but I did not sell pattern stanchions, gearbox- and engine parts etc.

Andover Norton frequently gets such pattern parts sent by people who have bought them from "Norton specialists", assume they came from us, and complain to us about their quality or rather lack of it. There are a lot of true tales I could tell. But not about GPM pistons, I am afraid. According to my experience they do their job just fine. If you prefer to use some vintage product that can- or can't- be found in the size you need when you need it is your decision. This is no option for Andover Norton, who have to supply the correct quality product immediately, in the necessary quantity, to the worldwide net of Norton dealers and customers. To rely on obscure leftovers is not an option for us.

Regards

Joe Seifert

Joe, you did answer me on this. On this very forum. I should have replied at the time - and am now about to.

Regards, Rich.

Previously wrote:

"In the classic bike scene people often fondly imagine that certain original parts are better than today's offerings. I just read in another forum about the original Commando seats being so much better than what is in the market today, because their foam was far better. I could have told the author of that comment about the seat I had on my Commando Interstate I bought new in April 1977, and how I, much slimmer and lighter then, sat on the seat pan after only about 10.000 miles because this then "much superior foam" had already collapsed after a few months in 1977....."

Sorry Rich,

Comes from being involved in Norton parts professionally, reading three forums every day and getting older and more forgetful.

Apologies

Joe

Dont know about using a file but many atime has found me with various grades of emery paper and a piston with scarfing marks oh happy days

Previously wrote:

Anna,

I find that remark in bad taste and it is far off the mark.

Our "family racer" engine was built about ten years ago with GPM pistons (that it still runs on), my '68 Fastback about 15 years ago (ditto). The man who builds the best, i.e. most reliable and fastest Norton engines in Germany, Rudi Kolano, actually PREFERS GPM pistons to Hepolites, including for 850s, these being the only Commando pistons that are still available from AE Hepolite.

The fact that I had my very own engines built with GPM pistons YEARS before I "sat on a mountain of GPM Pistons in my warehouse"- remember I only bought Andover Norton in April 2007- speaks for itself. At that time I ran Norton Motors GmbH in Germany- as I do to date- and still had AE Hepolite pistons in stock for those customers who insisted on them. So I had an alternative. Had I thought the GPMs were no good, would I have used them in my own engines?

In the classic bike scene people often fondly imagine that certain original parts are better than today's offerings. I just read in another forum about the original Commando seats being so much better than what is in the market today, because their foam was far better. I could have told the author of that comment about the seat I had on my Commando Interstate I bought new in April 1977, and how I, much slimmer and lighter then, sat on the seat pan after only about 10.000 miles because this then "much superior foam" had already collapsed after a few months in 1977.....

As you don't know me you don't know I decline to sell substandart stuff to my customers. You also don't know I ride Nortons and for how many miles I have done it. Even before I owned Andover Norton I insisted on Genuine Andover Norton product for my customers. There were always cheaper alternatives- and are to date- but I did not sell pattern stanchions, gearbox- and engine parts etc.

Andover Norton frequently gets such pattern parts sent by people who have bought them from "Norton specialists", assume they came from us, and complain to us about their quality or rather lack of it. There are a lot of true tales I could tell. But not about GPM pistons, I am afraid. According to my experience they do their job just fine. If you prefer to use some vintage product that can- or can't- be found in the size you need when you need it is your decision. This is no option for Andover Norton, who have to supply the correct quality product immediately, in the necessary quantity, to the worldwide net of Norton dealers and customers. To rely on obscure leftovers is not an option for us.

Regards

Joe Seifert

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Hele and Bert Hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign replacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myself ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon PS No wonder people leave the Norton Owners Club

Anna,

Yes, indeed, it touches a raw nerve if somebody is totally unfair to me.

As for those parts for the legendary Norton Manxman, Andover Norton never pretended they had all parts for it. In fact, I just answered the questions of a journalist regarding Dominator spares and retold the sad fact a Managing Director of Norton Motors (1978) Ltd had all technical drawings for Dominators he could get his hands on dumped around 1985- note that Andover Norton had nothing to do with this stupid act- and we have since redrawn some vital parts to enable us to re-manufacture them.

Furthermore, the Manxman was built in negligible quantities, which can not support a full spares service commercially, compared to the Commando. In my opinion that is what I have paid my N.O.C. Club membership fees for in the last thirty year: for the NOC to support the owners of models with spares that are not a commercial proposition. If the Club Spares Scheme chooses to ignore them, and instead decides to sell pirate spares for Commandos, feel free to complain to the Club about it. I have done so already.

I do not need to know better than Doug Helan (whoever that is) or Bert Hopwood by offering pistons today the manufacturer of which went bust probably 40 years ago. The late Doug Hele- a man I met and admired- or Bert Hopwood, a man who was responsible for the production lines of motorcycle factories, would not seriously insist on using something that was last made about 40 years ago to serve today's customers. They would gladly offer a current product that does the job. And as for your odd idea Hele would decline to use "non-British" technology, guess where the barrels of the works Domiracers were Nicasil plated- at Mahle in Stuttgart, Germany, at Doug Hele's request.

Your comment is in bad taste, as was the previous one.

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Helan and bert hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign repacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myslef ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon Ps No wonder people leave the Norton Owners Club

Previously wrote:

Anna,

Yes, indeed, it touches a raw nerve if somebody is totally unfair to me.

As for those parts for the legendary Norton Manxman, Andover Norton never pretended they had all parts for it. In fact, I just answered the questions of a journalist regarding Dominator spares and retold the sad fact a Managing Director of Norton Motors (1978) Ltd had all technical drawings for Dominators he could get his hands on dumped around 1985- note that Andover Norton had nothing to do with this stupid act- and we have since redrawn some vital parts to enable us to re-manufacture them.

Furthermore, the Manxman was built in negligible quantities, which can not support a full spares service commercially, compared to the Commando. In my opinion that is what I have paid my N.O.C. Club membership fees for in the last thirty year: for the NOC to support the owners of models with spares that are not a commercial proposition. If the Club Spares Scheme chooses to ignore them, and instead decides to sell pirate spares for Commandos, feel free to complain to the Club about it. I have done so already.

I do not need to know better than Doug Helan (whoever that is) or Bert Hopwood by offering pistons today the manufacturer of which went bust probably 40 years ago. The late Doug Hele- a man I met and admired- or Bert Hopwood, a man who was responsible for the production lines of motorcycle factories, would not seriously insist on using something that was last made about 40 years ago to serve today's customers. They would gladly offer a current product that does the job. And as for your odd idea Hele would decline to use "non-British" technology, guess where the barrels of the works Domiracers were Nicasil plated- at Mahle in Stuttgart, Germany, at Doug Hele's request.

Your comment is in bad taste, as was the previous one.

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Helan and bert hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign repacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myslef ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon Ps No wonder people leave the Norton Owners Club

hello joeyou see my surname is Dixon And My Great Uncle was Freddie W Dixon If You go buy the book ,by Hayens Books writen by David Mason ,The Man with the Heart Of a Lion, In you will see the a list of Patents He registered among them is the four wheel drive and oil pumps and The Allen key and one that is not there is the disc brake and Carburetters and the ABS system and meany more he tort Doug Hele when he was a young man working at Dougles in Bristol and he was very close friends with Rex McCandless and Ernest Lyons and Fred Clarke and Rex judd and Big Burt Le Vack and jimmy simpson and Howard Davies HRD And meany more so when it comes to engineering its in my blood line my father was a engineer on my grandmothers side there another Uncle Jack Ernest Moore He worked with Burt Hopwood a Engineer and Designer and I have followed the line of Engineers so when I see Bad Engineering it get my goat ?As for the Dominator techical designs from Bracbridge Street I have held them in my hands and are by now with the Treasurer of the Norton Owners Club and They need Sorting out ? As For The Norton Manxman 650 built from November 7th 1960 to September 1961 there was some 900 machines built all sent to Berliner Motor Corp, New Jersey USA and I have a Parts List For these Machines And they are Really Good Motorcycles the Ride I Love one One I have ? Yours Anna J Dixon

Previously wrote:

Dont know about using a file but many atime has found me with various grades of emery paper and a piston with scarfing marks oh happy days

seconded

dont we get bitchy , how old are we ???

life is short ,

enjoy your motorcycle, and if it stops , fix it as you will, its your choice.

old age sure makes some bitter,

What about their's http://www.vintagemotorcyclepistons.co.uk pistons?

Fritz

Going back 20 years!,I could not find any plus 10 pistons for my 99, I found some bare 650ss pistons at Russels bought rings and clips from a specialist and re-used my 99 pins, I would be interested in finding out what the CR works out to be. With regard to emery/sandpaper I would never think of using these on pistons, A fine file is the tool.

Previously joe_seifert wrote:

Anna,

Yes, indeed, it touches a raw nerve if somebody is totally unfair to me.

As for those parts for the legendary Norton Manxman, Andover Norton never pretended they had all parts for it. In fact, I just answered the questions of a journalist regarding Dominator spares and retold the sad fact a Managing Director of Norton Motors (1978) Ltd had all technical drawings for Dominators he could get his hands on dumped around 1985- note that Andover Norton had nothing to do with this stupid act- and we have since redrawn some vital parts to enable us to re-manufacture them.

Furthermore, the Manxman was built in negligible quantities, which can not support a full spares service commercially, compared to the Commando. In my opinion that is what I have paid my N.O.C. Club membership fees for in the last thirty year: for the NOC to support the owners of models with spares that are not a commercial proposition. If the Club Spares Scheme chooses to ignore them, and instead decides to sell pirate spares for Commandos, feel free to complain to the Club about it. I have done so already.

I do not need to know better than Doug Helan (whoever that is) or Bert Hopwood by offering pistons today the manufacturer of which went bust probably 40 years ago. The late Doug Hele- a man I met and admired- or Bert Hopwood, a man who was responsible for the production lines of motorcycle factories, would not seriously insist on using something that was last made about 40 years ago to serve today's customers. They would gladly offer a current product that does the job. And as for your odd idea Hele would decline to use "non-British" technology, guess where the barrels of the works Domiracers were Nicasil plated- at Mahle in Stuttgart, Germany, at Doug Hele's request.

Your comment is in bad taste, as was the previous one.

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Helan and bert hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign repacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myslef ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon Ps No wonder people leave the Norton Owners Club

Don't worry Joe... Anna not Anne seems to put herself up as the absolute authority of anything Norton. If she was a marine engineer, I would not envy her boss reading her technical reports. Maybe this comment will touch a nerve ??

Colin

Previously Colin Fairall wrote:

Previously joe_seifert wrote:

Anna,

Yes, indeed, it touches a raw nerve if somebody is totally unfair to me.

As for those parts for the legendary Norton Manxman, Andover Norton never pretended they had all parts for it. In fact, I just answered the questions of a journalist regarding Dominator spares and retold the sad fact a Managing Director of Norton Motors (1978) Ltd had all technical drawings for Dominators he could get his hands on dumped around 1985- note that Andover Norton had nothing to do with this stupid act- and we have since redrawn some vital parts to enable us to re-manufacture them.

Furthermore, the Manxman was built in negligible quantities, which can not support a full spares service commercially, compared to the Commando. In my opinion that is what I have paid my N.O.C. Club membership fees for in the last thirty year: for the NOC to support the owners of models with spares that are not a commercial proposition. If the Club Spares Scheme chooses to ignore them, and instead decides to sell pirate spares for Commandos, feel free to complain to the Club about it. I have done so already.

I do not need to know better than Doug Helan (whoever that is) or Bert Hopwood by offering pistons today the manufacturer of which went bust probably 40 years ago. The late Doug Hele- a man I met and admired- or Bert Hopwood, a man who was responsible for the production lines of motorcycle factories, would not seriously insist on using something that was last made about 40 years ago to serve today's customers. They would gladly offer a current product that does the job. And as for your odd idea Hele would decline to use "non-British" technology, guess where the barrels of the works Domiracers were Nicasil plated- at Mahle in Stuttgart, Germany, at Doug Hele's request.

Your comment is in bad taste, as was the previous one.

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Helan and bert hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign repacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myslef ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon Ps No wonder people leave the Norton Owners Club

Don't worry Joe... Anna not Anne seems to put herself up as the absolute authority of anything Norton. If she was a marine engineer, I would not envy her boss reading her technical reports. Maybe this comment will touch a nerve ??

Colin

Hi, John Phelan at Sheffield British M/cycles has over 9000 pistons in stock. I have just bought a pair of n.o.s hepolite 7.8 +20 for my 88. They were not cheap but if you want the best.......

Previously joe_seifert wrote:

Anna,

Yes, indeed, it touches a raw nerve if somebody is totally unfair to me.

As for those parts for the legendary Norton Manxman, Andover Norton never pretended they had all parts for it. In fact, I just answered the questions of a journalist regarding Dominator spares and retold the sad fact a Managing Director of Norton Motors (1978) Ltd had all technical drawings for Dominators he could get his hands on dumped around 1985- note that Andover Norton had nothing to do with this stupid act- and we have since redrawn some vital parts to enable us to re-manufacture them.

Furthermore, the Manxman was built in negligible quantities, which can not support a full spares service commercially, compared to the Commando. In my opinion that is what I have paid my N.O.C. Club membership fees for in the last thirty year: for the NOC to support the owners of models with spares that are not a commercial proposition. If the Club Spares Scheme chooses to ignore them, and instead decides to sell pirate spares for Commandos, feel free to complain to the Club about it. I have done so already.

I do not need to know better than Doug Helan (whoever that is) or Bert Hopwood by offering pistons today the manufacturer of which went bust probably 40 years ago. The late Doug Hele- a man I met and admired- or Bert Hopwood, a man who was responsible for the production lines of motorcycle factories, would not seriously insist on using something that was last made about 40 years ago to serve today's customers. They would gladly offer a current product that does the job. And as for your odd idea Hele would decline to use "non-British" technology, guess where the barrels of the works Domiracers were Nicasil plated- at Mahle in Stuttgart, Germany, at Doug Hele's request.

Your comment is in bad taste, as was the previous one.

Hello Joe Did that hit a raw nerve ? As for Andover spares I phone them with some parts numbers for my 1960 Norton manxman 650 and they did not have them on there parts list so up to now they not been much good and As for Gpm and JP pistons are You Saying that you know better than Doug Helan and bert hopwood they used BHB Piston In the 650 And they are now 50 years old and sill going strong ,well I think that BHB are better that some foreign repacement a wooden piston would better than them ,As for Parts I could not get from Andover Spares, I will Make Them Myslef ,As I have Made the rear mudguard for my 1954 Dominator 88 And there will be better then I can buy ? yours Anna J dixon Ps No wonder people leave the Norton Owners Club

Don't worry Joe... Anna not Anne seems to put herself up as the absolute authority of anything Norton. If she was a marine engineer, I would not envy her boss reading her technical reports. Maybe this comment will touch a nerve ??

Colin

Well I worked for my self , and had no problems in the past, The thing is these guys who sell so called Norton parts are only intrested in the mass market like the Norton Commando and every thing else is a Spin of from this, and Some Parts from the Norton Commando will not fit the Smaller twins range ,and its like wise with copied parts like Gandini Pistons and the like , and a Restorer would look for original parts than after market ones , so they like to get a motorcycle historicly correct, and not end up a mash up of parts ! Yours Anna J

It is amazing that Gandini pistons, made by manufacturers who supply OE pistons to mayor car manufacturers, are being called "low quality". The more so considering we (Nick Hopkins and myself) run our own private Nortons with them. My "family racing Commando" has done no end of racing miles on the first set of pistons, and neither we, nor our trade customers find these pistons problematic.

Resleeved cylinders, though not a problem in themselves, can suffer from poor fitting of the sleeves, too loose leading to bad heat transfer (result: seizure), too tight to distortion of the bore (result: seizure). Another popular fault is that modern engine repair shops disbelieve the Norton and/or piston manufacturers advice on clearance and tend to bore the cylinders to far tighter tolerances (result: seizure).

The advice on what some vintage Manxman had fitted originally, or what pistons were good forty years ago, does not help today's restorer at all. Pistons normally have a short shelf life- no dealer will voluntarily stock expensive items like pistons for decades-, so whatever Messieurs Hepworth and Grandage produced in 1964 in superb quality is of purely historical value today.

As usual, there are several possible reasons for the component failure (see above), but again as usual these are being ignored or denied. In this case perhaps understandably by people who may have made a mistake when they worked on that cylinder, and a part that can not answer back is therefore blamed for a failure that was most probably caused by poor workmanship.

Well the reason you say its in bad taste is you know well I am right, and I do not agree with your findings motorcycle part dealer or Not, B.H.B was made for Rolls Royce motorcars thats why Norton got them to make there pistons so they where the best quality of there time, and they have clearly stud the test of time too, and there has good today has they where back then, only Quality counts, that why the Norton Manxman was built in small numbers, the quality of the machnie was compermised and ended up a lower cost model, just like the Norton Commando its was all about costs and trying to make a motorcycle has Cost affective has possible, but with the Commando they did acheve this in a way, with a Mash up of parts But no less a good motorcycle ! and the reason than Gpm pistons expand is the cheaper Aluminum there made with and there heavy too, So when you buy these the machinist only gose with the original settings and tolerances witch are for the original parts , witch do not work with parts made else where, witch puts out the balance factors of the engine, Lighter pistons and stronger Connecting rods are better for the balance factors and a better engine , yours AJD

joe states that certain piston companies went bust 40 years ago but wasnt a lot of british industry just sold off and products copied and produced on the cheap. if they were sold at a price reflecting their quality i wouldnt mind but i think the manufacturer [not the retailer] is having us on. the new hepolite copies are quite cheap but like the others here i would prefer old familiar u.k. produced piston stock at familiar prices.

joe states that certain piston companies went bust 40 years ago but wasnt a lot of british industry just sold off and products copied and produced on the cheap. if they were sold at a price reflecting their quality i wouldnt mind but i think the manufacturer [not the retailer] is having us on. the new hepolite copies are quite cheap but like the others here i would prefer old familiar u.k. produced piston stock at familiar prices.

Hello Good Quality pistons are out there if you care to put some reseach in to find them, And do not belive every thing these retails tell you , there in Business and trying to make has much profit has they can ! thats Business!!! yours Anna J

Previously richard_payne wrote:

It's strange Joe (and I'm in danger of going way off topic here) but my understanding of 'shelf life' has always been to do with perishables - in an engineering context in relation to seals and hose etc. Sorry to quote Wiki but their explanation is pretty well the one that I would use.http://en.wikipedia.org/wiki/Shelf_lifeAs I said, I've used GPMs without problems (except for breaking my first cast oil ring during assembly !) but they wouldn't be my first choice and of course they don't feed my NOS autojumbling addiction.Friends with M20s in particular refer to a quite substantial weight increase over OE and certainly more than that caused by oversizes.Could you not machine an extra set of valve pockets in the Hepolite 750 pistons and sell them off as non-handed 'universals' ? (Why are there no 'smilies' here ?)Rich.

I have run the GPM's without issue. Slightly heavier? yes! But both pistons are exactly the same weight, not so with a net of NOS Hepolites I have

As with any piston, do not fit the piston to the cylinder using the Norton workshop manual, use the specs from the piston manufacturer (whomever you choose). I have seen several people sieze new pistons because they refused to read the directions that came with the pistons "been doin this for years sonny, don't tell me how to fit pistons!" FAIL!

Skip

GPMs - no problem. Original Hepolites - quite an impressive collection of debris. I'll certainly not be looking for NOS Hepolites next time I need a rebore.

Just out of curiosity, why has a post from 2010 been resurrected? I very much doubt that Laurent is still waiting for an answer (or has a gremlin got into the dating system, and, it is actually a recent post?).

Previously richard_payne wrote:

It's strange Joe (and I'm in danger of going way off topic here) but my understanding of 'shelf life' has always been to do with perishables - in an engineering context in relation to seals and hose etc. Sorry to quote Wiki but their explanation is pretty well the one that I would use.http://en.wikipedia.org/wiki/Shelf_lifeAs I said, I've used GPMs without problems (except for breaking my first cast oil ring during assembly !) but they wouldn't be my first choice and of course they don't feed my NOS autojumbling addiction.Friends with M20s in particular refer to a quite substantial weight increase over OE and certainly more than that caused by oversizes.Could you not machine an extra set of valve pockets in the Hepolite 750 pistons and sell them off as non-handed 'universals' ? (Why are there no 'smilies' here ?)Rich.

MessagetoRichard Payne..... ..... WhatalaughMessage to Anna: The "fastest Indian" ran on pistons madeofmeltedcokecans!!!!! I'mgonalookaftermine.....

No it was one of FORD and TWO of Cheviy YOURS anna J

I have run the GPM's without issue. Slightly heavier? yes! But both pistons are exactly the same weight, not so with a net of NOS Hepolites I have

As with any piston, do not fit the piston to the cylinder using the Norton workshop manual, use the specs from the piston manufacturer (whomever you choose). I have seen several people sieze new pistons because they refused to read the directions that came with the pistons "been doin this for years sonny, don't tell me how to fit pistons!" FAIL!

Skip

Hello Heavy pistons put the balance out, and thats not good for you engine, the lighter piston the better , yours Anna J

Previously Skip Brolund wrote:

I have run the GPM's without issue. Slightly heavier? yes! But both pistons are exactly the same weight, not so with a net of NOS Hepolites I have

As with any piston, do not fit the piston to the cylinder using the Norton workshop manual, use the specs from the piston manufacturer (whomever you choose). I have seen several people sieze new pistons because they refused to read the directions that came with the pistons "been doin this for years sonny, don't tell me how to fit pistons!" FAIL!

Skip

Hello Heavy pistons put the engine out of balance and thats not good for your engine, the lighter piston the better , yours Anna J

i never thought i d read that coke cans could be used in an engine as piston substitutes on this site!

Previously benjamin_gradler wrote:

Geoffrey Myers said:

" Filing the pistons down where they are rubbing must be the best joke I've heard for a long time. "

I am glad to entertain you. If you want to read an entire book of "jokes" like that, then get a copy of the famous book on tuning British engines Tuning for Speed by P.E. Irving, it was the bible of tuning British engines for many years and tells you exactly what marks to look at on a piston and which to use a file on and how to do it.

Also, with it's early two stroke racers, Yamaha instructed owners to rev an engine with a fresh top end job until it seized, then take the top off and work on the pistons with a file.

You Johnny-come-lately, know-nothing twit.......

I agree. Geoffrey Myers needs to read more technical books. I recommend the training manuals for Army and Navy servicemen. They have been around since before the second world war and treat internal combustion engines in more detail than you will ever need. Like the rapid break-in of fighter plane engines with Ajax cleaner before you assemble the parts. Funny?... Never heard of it?... Well the Air Force did it. Maybe you need more education.

Next you'll be saying: "Ignite the fuel by compressing it? I don't believe you. Wait till I tell the lads down at the pub. They'll have a laugh."

Please close this pointless thread down so Anna can go and take her medication and gaze at the wonderfull Manxman,maybe read about her family history. I think the guy has enough piston info for a while.

Please close this pointless thread down so Anna can go and take her medication and gaze at the wonderfull Manxman,maybe read about her family history. I think the guy has enough piston info for a while.

Hello Tony how are you feeling, now you should know I do not like taking drugs of any kind, Hurbs are much better, a nice Nettel sandwich with a bit of ham gose down nice, and a pint of guinness , hurbs have been use for centuries has medicens and do a better job the what you get off the shelf at the chemists and it free to, if you know your hurbs and how too use them, Has for pistons the Golden Rule if the piston has a stamp marks saying B.H.B , or Hepolex or Hepolite or AE auto parts there all top Qualtiy Piston made in england , the only other pistons of the same or simlar quality are J.P. pistons or Wisco or motocovo if you can get them, the piston rings you have to be very carefull with and mesure the free play around the side has well has the end gap witch should 0.008-0.0012 and side play 0.00012 to 0.00022 these are my clearance not the books and a lot finer tolerances . your piston to barrel tolerances shold be with in 0.003 on a piston with on rings fitted . to do this mesurement you need to mesure in three places with in the bore , you find all this information in your maintaince manuel Now has for GPm I have lots of records from owners that have had damage done or seizurs to there machines after using GPm products , but there are no records of how these were fitted, or how they were re-bored , So I cannot give any real judgement on this Product , But you pays your money and takes your chances, Please NOTE GPm Piston Rings Will Not Fitted Hepolite or Hepolex or BHB pistons they have a diffrent radius on the inside edge, But Hap-Jones rings fit nicely if you can find them , now your querys are anwered yours anna j happy spannering ! THE END