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Conrods

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Conrods

Posted by john_hall1 at July 25. 2017

Hi,

I bought an engine on Evil-Bay and on stripping it down with a friend's help, it  was found to have mismatched Con Rods in it, one from a 650 and one from an Atlas, so I will show my further ignorance and ask for Norton Heavy Twins are Connecting Rods Left and right handed and marked as such?

 

 

Many Thanks

 

 

Possibly clueless-John

Re: Conrods

Posted by anthony_curzon at July 25. 2017

I could add a picture of the differences but I do not know how to.

Re: Conrods

Posted by howard_robinson at July 25. 2017

Hiyah john - Not quite correct John.  Early 650s and early Atlases used the same con-rods  ( not handed ) .  Some years later they both changed to a stronger rod.  Then subsequently a hole was added to one side of the rod to spray a mist on the dry-side of the barrel.  These changes happened to 650s and Atlases around the same time.  So you may have a mix of types but not Models.  Cheers for now, Howard

Re: Conrods

Posted by anthony_curzon at July 25. 2017

The 650 and the Atlas used the same con-rods, but there was an earlier one and a later one as there was also a modified one with an oil hole. The earlier 650 and Atlas con-rods were on the fragile side. The way to tell is the earlier con-rods had a large circular cut out at the base of the con-rod and the later ones had a V shape and then that oil hole was added to pass oil onto the cylinder wall bores. There was many oiling modifications performed on the crankcases, oil junction block and piston rings.

Re: Conrods

Posted by john_hall1 at July 26. 2017

Previously anthony_curzon wrote:

I could add a picture of the differences but I do not know how to.

Go to attachments Tab and browse your Computer then click, (on mine, Linux based), you click OPEN, on yours it may be ADD picture or something similar!

Found shots on Ebay, these are exactly like, what was in the Atlas engine, I bought these only to find the Stronger rod marked on the  end elevation side, (long finger side), not shown in the Selle'rs pictures, there is a bit of a scam going on, on EBay where by the post some pictures to play a part in the description and then do not provide adequate word descriptions to match, so he, the Seller didn't post a shot of the side-ways elevation Con-rod damage, he also puts a Disclaimer where He will delete your negative Feedback if you don't talk to him first!

Cheers

 

 

John

Webmaster edit:  Attachment removed at request of poster.
Attachments

Re: Conrods

Posted by john_hall1 at July 26. 2017

Previously howard_robinson wrote:

Hiyah john - Not quite correct John.  Early 650s and early Atlases used the same con-rods  ( not handed ) .  Some years later they both changed to a stronger rod.  Then subsequently a hole was added to one side of the rod to spray a mist on the dry-side of the barrel.  These changes happened to 650s and Atlases around the same time.  So you may have a mix of types but not Models.  Cheers for now, Howard

Thanks, why design a fragile engine?

This is when I get frustrated by Motorcycle products, their Designers, Engineers and interfering Bean counters, if I had been talented in that direction I would have built the best engine I could of... and benefited by reputation on engine strength and durability!

 

 

Cheers

 

 

John

Re: Conrods

Posted by john_hall1 at July 26. 2017

Anthony,

Perhaps the engines I have got can be modified to encompass changes too!

 

 

Cheers

 

 

John

Re: Conrods

Posted by john_hall1 at July 26. 2017

Previously howard_robinson wrote:

Hiyah john - Not quite correct John.  Early 650s and early Atlases used the same con-rods  ( not handed ) .  Some years later they both changed to a stronger rod.  Then subsequently a hole was added to one side of the rod to spray a mist on the dry-side of the barrel.  These changes happened to 650s and Atlases around the same time.  So you may have a mix of types but not Models.  Cheers for now, Howard

Howard,

My Grandad was a Robinson! Based in Lancashire and with his brothers, Mining and railway workers, Wigan, Coppull, Mossy-Lea region, Wrightington! Then some of them went to Yorkshire, enemy country,  to Carlton Main pit, near Barnsley

Thanks for correcting my lack of in-depth  familiarity with heavy twins!

 

 

Cheers

 

 

John

 

Re: Conrods

Posted by john_hall1 at July 26. 2017

Anthony,

My friend has an Hillman Imp engine in a RE Constellation frame and it has done 300,000 miles without a major strip down!

Cheers

 

 

John

 

 

Re: Conrods

Posted by David Cooper at July 26. 2017

Designers do no build fragile machines if they can help it. Metal fatigue is the big issue with con rods. And the variation in life for identical parts can be huge. It takes large samples to get the data and that's a problem, especially for a small company in difficult financial times.

If today's computer analysis had been possible, they could have improved the life by reducing locally higher stress.

Imps should be good...with shorter stroke the con rod forces are much lower.

Norton could have added more weight but vibration would be worsened.

Re: Conrods

Posted by howard_robinson at July 26. 2017

John hello again - for many years the early 650SS con-rods performed very well and especially so in the Thruxton 500 Mile races in the early sixties.  I believe it was only when tuner entrants like Paul Dunstall and the like started serious tuning on the 650SS and Atlases that a stronger rod was required.  Seemingly when revving at 7K and having a piston seize caused the rod to snap at the base.  Curious ?  I have used and raced the early rods satisfactorily for many miles, though I have to confess that 7K in top was only a dream.   A word of caution though - please be sure to use a pair of whichever type you have.  One of each is a no no !  Regards, Howard from Lancashire !

Re: Conrods

Posted by anna jeannette Dixon at July 26. 2017

Hello,  That Friend of Mr John Hall Is ME!!! one  Anna J Dixon.Bs.mech and both connecting rods  have NO oil holes  the early type and the later Canoe V shaped type  has well  the guy who had built this motor had used blue silicon sealant  in doing so he laddered  it on   blocking up the scavenge side hole in the crankcase  we seem to get these numpties now and again  the crank now needs a regrind  has a result of his improper action   and thoughtlessness,  But OLD anna j will put things right in time,     yours    Anna J 

Re: Conrods

Posted by john_hall1 at July 26. 2017

Previously john_hall1 wrote:

Previously anthony_curzon wrote:

I could add a picture of the differences but I do not know how to.

Go to attachments Tab and browse your Computer then click, (on mine, Linux based), you click OPEN, on yours it may be ADD picture or something similar!

Found shots on Ebay, these are exactly like, what was in the Atlas engine, I bought these only to find the Stronger rod marked on the  end elevation side, (long finger side), not shown in the Selle'rs pictures, there is a bit of a scam going on, on EBay where by the post some pictures to play a part in the description and then do not provide adequate word descriptions to match, so he, the Seller didn't post a shot of the side-ways elevation Con-rod damage, he also puts a Disclaimer where He will delete your negative Feedback if you don't talk to him first!

Cheers

 

 

John

Re: Conrods

Posted by john_hall1 at July 26. 2017

 

 

 

Re: Conrods

Posted by David Cooper at July 26. 2017

I wonder what the real issue is with mismatched con rods?  Any weight difference will produce a rocking couple - but that will surely be much smaller than the out of balance inherent in a parallel twin.

And at the best part of £190 each, there has to be a very good reason to throw a con rod away!

Just asking...

 

Re: Conrods

Posted by john_hall1 at July 28. 2017

Previously David Cooper wrote:

I wonder what the real issue is with mismatched con rods?  Any weight difference will produce a rocking couple - but that will surely be much smaller than the out of balance inherent in a parallel twin.

And at the best part of £190 each, there has to be a very good reason to throw a con rod away!

Just asking...

Hi,

It looks like the engine has been seized at some point and perhaps someone has just cobbled the bits together together to make it saleable/swop-able it certainly, I would have thought be a bad idea to run with mismatched Con rods from a balance factor alone!

Cheers

 

John

 

Re: Conrods

Posted by john_hall1 at July 28. 2017

Previously anna jeannette Dixon wrote:

Hello,  That Friend of Mr John Hall Is ME!!! one  Anna J Dixon.Bs.mech and both connecting rods  have NO oil holes  the early type and the later Canoe V shaped type  has well  the guy who had built this motor had used blue silicon sealant  in doing so he laddered  it on   blocking up the scavenge side hole in the crankcase  we seem to get these numpties now and again  the crank now needs a regrind  has a result of his improper action   and thoughtlessness,  But OLD anna j will put things right in time,     yours    Anna J

 

Yep, left the motor in a right mess and a much more costly rebuild!

 

 

Cheers

 

 

John

Re: Conrods

Posted by anna jeannette Dixon at July 28. 2017
Previously john_hall1 wrote:

Previously anna jeannette Dixon wrote:

Hello,  That Friend of Mr John Hall Is ME!!! one  Anna J Dixon.Bs.mech and both connecting rods  have NO oil holes  the early type and the later Canoe V shaped type  has well  the guy who had built this motor had used blue silicon sealant  in doing so he laddered  it on   blocking up the scavenge side hole in the crankcase  we seem to get these numpties now and again  the crank now needs a regrind  has a result of his improper action   and thoughtlessness,  But OLD anna j will put things right in time,     yours    Anna J

 

Yep, left the motor in a right mess and a much more costly rebuild!

 

 

Cheers

 

Hello well one thing is you have now two set of conrod that need balancing up and one crankshaft that needs a regrind and a new set of main  bearings  FROM R&M   the canshaft is in very good order no signs of wear as is the followers  the barrel is a other story ,  best left S.E.P engineering.  for a recreation job  this bit will cost the most  howch !!  But at the end of this proess  you have a 3 million dollers Atlas engine           yours  Anna J

John

 

Re: Conrods

Posted by Gordon Johnston at July 28. 2017

Hi John,

You have our sympathy regarding eBay purchases... Most of us have been there. Anyway, I would suggest for peace of mind going for a set of new rods and putting your existing rods on ebay. You should at least recoup some of your expense. Thereafter, Norton engines are not difficult to rebuild with a bit of common sense and a good read of the manual.

As for bike design, if you look at a Norton Twin from one end to another it is full of engineering "compromises" but the whole is better than the sum of its parts which may explain why so many of us persevere with them long after their scrap-by date. The other explanation is sheer lunacy.

Re: Conrods

Posted by John Shorter at July 28. 2017

Not entirely lunacy, Gordon.  My first Norton was a '53 88, bought, second hand, when I was 19 years old.  Not the fastest bike on the road, but the best roadholding.  Over any reasonably long distance, it could keep up with, or beat, almost any other bike available.  I now ride a '54 model.  However, not quite so hard!  Although I find the "Runs", at the rallies I have attended, to be boringly slow.  I very rarely  ride on motorways, but, on normal roads (better in Spain than in the U.K.!), seldom get overtaken.  

 

;

Re: Conrods

Posted by Gordon Johnston at July 29. 2017

John, totally agree about the dismal pace of organised runs. You see a group of cyclists in the distance and 10 mins later you can still see a group of cyclists in the distance... I invariably arrive at various stops 20 mins before the rest.

The early 50s bikes were in my eyes far better engineered than the later ones. I have a 1951 A7 Star Twin which I have had for 40 years now. It gets used hard and often and has never failed to get me home (are you listening dear Norton?). I wouldn't hesitate to take it any distance.

Re: Conrods

Posted by John Shorter at July 29. 2017

We seem to have a lot in common Gordon, but, must not hog this thread.

Re: Conrods

Posted by john_hall1 at July 30. 2017

Previously anna jeannette Dixon wrote:

Previously john_hall1 wrote:

Previously anna jeannette Dixon wrote:

Hello,  That Friend of Mr John Hall Is ME!!! one  Anna J Dixon.Bs.mech and both connecting rods  have NO oil holes  the early type and the later Canoe V shaped type  has well  the guy who had built this motor had used blue silicon sealant  in doing so he laddered  it on   blocking up the scavenge side hole in the crankcase  we seem to get these numpties now and again  the crank now needs a regrind  has a result of his improper action   and thoughtlessness,  But OLD anna j will put things right in time,     yours    Anna J

 

Yep, left the motor in a right mess and a much more costly rebuild!

 

 

Cheers

 

Hello well one thing is you have now two set of conrod that need balancing up and one crankshaft that needs a regrind and a new set of main  bearings  FROM R&M   the canshaft is in very good order no signs of wear as is the followers  the barrel is a other story ,  best left S.E.P engineering.  for a recreation job  this bit will cost the most  howch !!  But at the end of this proess  you have a 3 million dollers Atlas engine           yours  Anna J

John

I prefer a six million Dollar machine, I presume you are referring to a pun on the Lee Majors character of the 70s & 80s!

 

 

Cheers

 

 

John

 

Re: Conrods

Posted by john_hall1 at July 30. 2017

Previously howard_robinson wrote:

John hello again - for many years the early 650SS con-rods performed very well and especially so in the Thruxton 500 Mile races in the early sixties.  I believe it was only when tuner entrants like Paul Dunstall and the like started serious tuning on the 650SS and Atlases that a stronger rod was required.  Seemingly when revving at 7K and having a piston seize caused the rod to snap at the base.  Curious ?  I have used and raced the early rods satisfactorily for many miles, though I have to confess that 7K in top was only a dream.   A word of caution though - please be sure to use a pair of whichever type you have.  One of each is a no no !  Regards, Howard from Lancashire !

You know Howard, this is how the Jap bikes scored especially Honda in the early days, with free-revving engines and motors that were nigh on unburstable, I have a Kawasaki ZL400 that red-lines at 12,000 rpm, ultra-short-stroke 44mm i think almost like a Honda 50.

I did read that in the old days, BMW engines had a 25-30% safety factor, you got 60bhp   and the engine was safe up to high 70s!

 

Cheers

 

 

John

Re: Conrods

Posted by john_hall1 at July 30. 2017

Previously howard_robinson wrote:

John hello again - for many years the early 650SS con-rods performed very well and especially so in the Thruxton 500 Mile races in the early sixties.  I believe it was only when tuner entrants like Paul Dunstall and the like started serious tuning on the 650SS and Atlases that a stronger rod was required.  Seemingly when revving at 7K and having a piston seize caused the rod to snap at the base.  Curious ?  I have used and raced the early rods satisfactorily for many miles, though I have to confess that 7K in top was only a dream.   A word of caution though - please be sure to use a pair of whichever type you have.  One of each is a no no !  Regards, Howard from Lancashire !

 

Racing indeed does improve the breed!

You know Howard that is where, Japanese bikes scored in the early days, high RPM and almost unburstable engines, especially Honda! I have a mid-sizes Kawasaki ZL that revs to 12.000 rpm, ultra-short stroke 44mmm I think, almost the same as a Honda 50! I read some years ago that the Old BMW engines especially the K Series had in design 25% to 30% safety margins you got 75bhp and the engine could run to 100bhp!

 

Cheers

 

 

John

Re: Conrods

Posted by john_hall1 at July 30. 2017

Previously David Cooper wrote:

I wonder what the real issue is with mismatched con rods?  Any weight difference will produce a rocking couple - but that will surely be much smaller than the out of balance inherent in a parallel twin.

And at the best part of £190 each, there has to be a very good reason to throw a con rod away!

Just asking...

 

Suspect the engine was put together from a collection of spare parts, even I can spot the fake bikes on Ebay that claim to be RGS and 650SS etc, I know Club Members would not do this but because of the "Investment" Value of machines, all kinds of Scammers and Riff-raff are on into the Classic Vintage Bike scene now!

 

 

Cheers

 

 

John

 

Re: Conrods

Posted by john_hall1 at July 30. 2017

Previously Gordon Johnston wrote:

Hi John,

You have our sympathy regarding eBay purchases... Most of us have been there. Anyway, I would suggest for peace of mind going for a set of new rods and putting your existing rods on ebay. You should at least recoup some of your expense. Thereafter, Norton engines are not difficult to rebuild with a bit of common sense and a good read of the manual.

As for bike design, if you look at a Norton Twin from one end to another it is full of engineering "compromises" but the whole is better than the sum of its parts which may explain why so many of us persevere with them long after their scrap-by date. The other explanation is sheer lunacy.

Isn't it a facet of Synergy the " Sum of the parts" performing better than an analysis of components, I have read that in Eastern religions of the Far East a Motorcycle and it's component parts are not exactly thought of as inanimate as we probably mistakenly would think of them in the West. I have had motorcycles that seemed to have their own character funnily enough the British ones always had most of this elusive quality without the philosophy 0f Zen behind them!  It's a Deva thing...I am assured!

 

Cheers

 

 

John

Re: Conrods

Posted by anna jeannette Dixon at July 30. 2017
Previously john_hall1 wrote:

Previously Gordon Johnston wrote:

Hi John,

You have our sympathy regarding eBay purchases... Most of us have been there. Anyway, I would suggest for peace of mind going for a set of new rods and putting your existing rods on ebay. You should at least recoup some of your expense. Thereafter, Norton engines are not difficult to rebuild with a bit of common sense and a good read of the manual.

As for bike design, if you look at a Norton Twin from one end to another it is full of engineering "compromises" but the whole is better than the sum of its parts which may explain why so many of us persevere with them long after their scrap-by date. The other explanation is sheer lunacy.

Isn't it a facet of Synergy the " Sum of the parts" performing better than an analysis of components, I have read that in Eastern religions of the Far East a Motorcycle and it's component parts are not exactly thought of as inanimate as we probably mistakenly would think of them in the West. I have had motorcycles that seemed to have their own character funnily enough the British ones always had most of this elusive quality without the philosophy 0f Zen behind them!  It's a Deva thing...I am assured!

 

Cheers

 

 

John

   Hello We did have four cylinder engine design for motorcycle some like the BRM of 1949 was years ahead of this time we had the Engineers But Not the Management the light was On but no one at home  !!! 

Re: Conrods

Posted by john_hall1 at August 02. 2017

Anna,

They, Norton, BSA could have easily modified a Coventry Climax Featherweight  engine like Rootes did with the Hillman Imp engine, from the Mark 2 version, stronger block variety, giving 55/60 bhp straight off the mark!

This could have been at least 5 years before Honda and Kawasaki did it>  The original Rondine later modified by Gilera was designed in the early to mid 1930s! The Italians get very little credit for engineering the first really successful across the frame four!

 

The nice link to Norton with the Rootes Imp engine is Leo Kuzmicki was involved in the design and development of the Imp engine, where earlier on in his career, he being a Cylinder Head specialist, had tuned the 20M and 30M Manx racing engines!

 

Geoff Duke asked for a 4 in 1951/52 and he then left for Gilera, when Norton/ the British Industry failed to supply the  4 cylinder engine needed, the writing was on the wall, pre WW2, He left Norton, with much personal criticism from detractors who accused him of being disloyal! Jock West and BMW anyone?

Cheers

 

John

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