650SS rebore

If it was my bike I would not consider a re-line unless it was leaving a smoke trail and burning lots of oil and missfiring due to oiled plugs. If its blowing a bit of oil from the breather I would re-route it so as not to lube the tyre and consider some additional breathing .Liners can give problems and running in is a pain too . If its running OK what is there to gain?.

I have been happy tohave barrels re-sleeved. Most recent ones were done by RGM. No problems encountered.

Previously lance_crossley wrote:

Hello, Fellow Noccers.

My first post in this forum though Iâve been a member since I bought my 1966 650SS back in 1980, so please be gentle with me! I never cease to be amazed at the depth of knowledge of you folk and am very envious.

One question I hope you can answer concerning my 650SS - I have just stripped it down to try and resolve a running problem which I may bore you all with via Roadholder in due course so you can marvel at my ineptitude. The bore was +60 when I got the bike, which is the maximum rebore size as far as I'm aware, and now would be an ideal opportunity to get it back to standard as there is a very slight ridge at the top of the bore and if I use the bike higher up the rev range it does seem to stress the oil retention somewhat by over pressurizing the engine. However I seem to recall at some stage having read that itâs not possible to sleeve this engine to do this. Please can someone advise if this is indeed the case? If not and it is possible to do what I would like to do then are there any specific instructions I would need to give the engineer regarding tolerances of the finished article?

Thanks in anticipation.

Hello The Minimum oversize for any 650 is 40+ oversize your Barrels Need a resleeve Now, the Best guys to do this is SEP Engineering in Kegworth Derbyshire Phone 01509 673295 , piston where BHB part number 23270 and 23271 compression ratio 8:9:1 these are the original pistons for the 650 models but if these are unobtainable then JP pistons are the next best , from F.W.Thorntons of orleton lane Wellington Telford .Shropshire , TF1 2BG Phone 01952- 252982

Now I Hope this Helps Yours Anna J

Previously lance_crossley wrote:

Thanks, Anna, for the info and also Gordon for youro comments.

I have in fact decided to bite the bullet and have left my barrel and head with Lee Brothers in Sowerby Bridge, West Yorkshire to fettle. They've been trading since 1963 so should know what they're doing by now! They're also putting in new guides and valves and seat cutting whilst it's in bits and skimming the head to make sure it's completely flat. I had a head gasket go a while ago and and while I had a try myself to rub the head joint down on a glass plate it wasn't easy and I'm not sure it was 100% successful so now I will be sure it's OK. Can't wait till it's all back so I can rebuild and try it out!

Warning Do Not Fit the old type cast iron Valve Guides they have a tendancy to break inside the Guide , I have fitted My Norton Manxman 650 with high Grade Bronze valve guides you need to re-cut the valve seat to match the New Valve guide angle and do try to keep the spigots on the top of the barrel if you can they can be troublemsome at time by cracking , but in good order there on bother, and do give a good seal, between cylinder and cylinder head, Now has for piston try Dale Middelhurst he real good in this department and He knows his 650s too, yours Anna J

I am a bit surprised that your bike is smoking and using oil after a rebore. I wonder what tolerances were used. Are the piston rings gapped correctly and are the gaps spaced at 120 degrees to each other? Much will depend on what oil you are using. I would suggest a classic 20-50 multigrade or a straight 40 monograde. Should you use a modern synthetic or semi-synthetic oil, your new pistons and rings will never bed in. Running in is a bit of a black art. Don't labour it, let it run on the downhills, gradually increase the throttle openings. It could take 1,000 miles before being fully run in.

With typical light classic use and the use of modern lubricants its entirely possible that the machine will not be run in during your ownership and will burn oil and give a poorer performance than it should.This happens more than you would think,nearly happened to me.

Well If your in yorkshire you can get hold of Milliers Running in oils a special oil for this job you need to change oil on a regular bases like every 500 to start with and keep the revs down if you can but n riding up hills you need revs has it in a lower gears and riding to 60 mph would be ok but running in takes a lot of time and love, of your motorcycle planning maybe need to ride some back road ,where there is less traffic and riding do try to make some stops now and then in your trips out and take in the country side on nice days outings have fun and enjoy your nice machnie yours anna j

Thanks for the comments.

I'm using mineral multigrade so not the modern synthetic stuff. I gapped the rings and ensured the gaps weren't together. From my past riding record it will take me a few years to get to the 1,000 miles mark but my aim is to get out and about a bit more now I'm retired so hopefully I can get the slow and steady stuff done more quickly than in the past. I'll have to check out Anna's suggestion of using Millers special oil. It might be worth a try.

Lance give them a ring on there information desk then you can get all the right information and then make your mind up if your going to try it out or not, before you buy anything, its alway best to get the right information before doing something new , do have some nice fun in the sun yours Anna J Dixon

After the re-bore on the LH barrel, what now are the compression readings?

Mike

Out of interest do you know if the re sleeve was done with straight liners with no top collar ? using a interference fit, i only ask as i am going to have to start my mercury soon and the engine came with the barrels re sleeved to standard and new pistons, its due for its first run since its rebuild. i have heard of a sleeve moving down and wrecking the crankcases!

I had both sleeves move on an Atlas barrel I once had rebuilt. Fortunately without damaging the engine. It just stopped once the rings had jumped the sleeve top lips. It was returned to the engineers who pegged the liners in place with brass pins. I strongly suggest that you get this done or some alternative fixing.

Previously Phil Hannam wrote:

I had both sleeves move on an Atlas barrel I once had rebuilt. Fortunately without damaging the engine. It just stopped once the rings had jumped the sleeve top lips. It was returned to the engineers who pegged the liners in place with brass pins. I strongly suggest that you get this done or some alternative fixing.

thanks Phil, i do not know who did the resleeve, its been done a good few years before i aquired the bike but as you can tell i am nervy about it.thanks for the advice, arthur.

No problem, sorry to high jack your thread, good luck with the running in.

Regarding your comment with respect to smoking after coming down a hill, if I've interpreted your comment correctly are you saying it's smoking on the overrun because I've always understood this to be a valve guide wear problem. Many, many years ago John Hudson told me that the best way to decide if smoking is a ring or valve guide problem is by blanking off the rocker feed, if the problem persists it's a piston ring / cylinder problem and if the problem goes away then it's a valve related problem. John said that it is quite safe to run the bike for up to 40 miles like this but I imagine most of us would prefer to do a lot fewer miles than that.

On the subject of running in, I'm not a great advocate of running in. After 30 or 40 fairly gentle(ish) miles my own bikes would be ridden normally but just not allowed to labour or be taken over 6,000 revs for a couple of hundred miles.

The bedding in of an engine depends very much on the machinery used to refurbish the parts. Modern engineering companies can produce bore and crankshaft finishes that are so accurate that only minimal 'running-in' is now required beofre normal use of an engine.

I had my Commando 750 rebored 18 months ago andthis yearmy Dommie 650 got the full works with a crank regrind and cylinder rebore. When I asked about recommended bedding-in miles, for my Commando I got one of those strange 'here's an idiot' looks from the man with dirty hands.

The command was to give the engine some work to do from day 1 and the first 200 miles. Nothing excessive, such as a few Track Day sessions, but enough revs and gears to help bed the rings in quickly.

It worked for me on both engines with excellent compression and almost zero oil consumption coming up when around 400 miles had been covered. I was impressed because prior to this a rebore generally resulted in at least a 1000 miles of tedious motoring using minimal throttle. Not any more, thank goodness.

Running in instructions for Lycoming engines on small piston engined aircraft warn AGAINST using small throttle openings. Full throttle for take off from the outset. A new or just rebored engine will leave some blue smoke for the first half hour of flying then that's it, treat as normal.

Certainly the ancient instructions of 30mph for the first 1,000 miles sank with the Ark.

Previously lance_crossley wrote:

Thanks for your comments, Phil & Gordon.

Having this sort of comment from people I trust within the club gives me the confidence to now try this route. I'm not prepared to instantly trust comments made on the net by unknown people as you never know whether or not they're having a laugh at other's expense. Happy to give this a go now. That will make riding much more pleasureable! Off to get the bike out now before it rains.

I see two elements to "Running In"; surfacepreparation andbedding down. With modern machinetoolaccuracy surface prep isminimal as thetwo, matingfaces areso well finished any blemishesareminimal. The reciprocating engine runs in bearings that are pre manufactured( No lapping and scraping nowadays)so little willcomefrom"Surface prep" there. The gas tightseal of an ICengine determinesits operating effectiveness; valve and seat piston and bore arethe mainarea for this part. Two itemsmanufacturedseparatelyandmated to form a gas tightseal with over a temperature and pressure range. Cylinder finishwithcrosshatch oil retention willalways leave a peakand atrough under themicroscope. This needs to be allowed to clean up by using the matingmaterial surface( piston ring)to blend into it and form that seal, Allmodern enginesarerotated byexternal powertoform thatinitial surfaceon initial manufacture andloadsapplied and increased at variouslevelsto make thatseal themore effective. Valve seats pressed intocylinder heads and valvesmass manufactured arebrought togetherandexpected by their engineeringtolerance to seal effectively, instantly; there is nolapping orpolishing done. So these need to mate to an optimum level again byrepeated fit anddisplacement. surface prep...

Thenbeddingdown; temperature cycles,pressurecycles,vibration,recent manufacturing stresses such as forging, grinding boring, broaching,planing,millingall impartforce into the materials and potentiallyare not whollyaccurately sizedthoughwithin a tolerance under static conditions. They also can introduce debris, thatpart from the component under varying environmental conditions, contaminating theinternals and wouldbebetter offwithout. and of courseweaddthesensitivegolden substance... ...oil; thelife blood of thereciprocatingengine. Too goodand nothing mates'too bad anditwill seize or wear out rapidly, too much andyoucan overpressure internalsand causeall sorts of issues. All thesecan be managed or observedunder"running in"conditions.Use all your senses toidentifywhat'shappening;sight, sound, smell, feel all return yousomething when running up a motor. Temperature andpressure management, vialight throttles initially,down hilloverrunsin highgear, heat cycles and build integrity checks fora few runs will benefit thelongevity and performance of any motor. Preset mileage or time is not necessary itsgetting it up to best fit then, press on....

Thanks for your comments, Jonathan.

I think your description pretty comprehensively covers the situation!

I set out for another run a couple of days ago and became embroiled in the frequent traffic nightmare that is all too often prevalent in Hebden Bridge. I was tempted to regale you all with my hatred of this place, having endured it on my daily commute for almost 20 years prior to retiring but decided to spare you! Having negotiated this and reached calmer roads the engine decided to run on only one cylinder so I turned round, battled with the traffic from the other direction and eventually made it home, even up the steep track to my house on just the one cylinder. Out with the plug on the offending cylinder to find it rather oiled up and slightly whiskered, as per the attached. It did spark OK out of the engine but obviously didn't like the more severe conditions in situ. The good news was that the other plug showed signs of good colouration so I think the carburation should be about right after my switch back to twin Monoblocs, as far as I can tell so far at my reduced level of running. In with a new set of plugs - brand new Champion N9Ys I happened to have - one still in its original packaging! - and it fired up again OK so either the newly installed Millers Running In Oil is the problem, or it could bea faulty plug or perhaps the lengthy slow battle with the traffic was the cause? Or perhaps a mixture of all three? If it was the oil Iâd expect it to affect both cylinders/plugs so itâs probably the plug. Cue for Anna to tell me to switch to Bosch plugs! Might even do this at some stage but Iâll see how I go with what I have at the moment.

Eventually I might get it running just how I want it!

Well N9Y are two hard for a 650 even with twin carbs you better of in our days with one carbuettor a 389./67 300 main jet 3.1/2 cutway side 25 pilot jet 106 needel and your cylinder is picking some oil up has its not run in yet your ok up to 50 mph , have you a big 22tooth sprocket on the engine a 21 tooth is a bit better to start with has your area is up and down hills the extra rev or two may help things

Try these bosch W7DTC OR NGK BR7ET

I suspect a few 650 owners would have raised eyebrows on reading that you are using N9Y plugs in a 650 engine. These are, as Anna points out, a bit too hot plus around 4 or 5mm longer that an N4 or equivalent. Consequently puts the firing point right on top of the piston.

I know that these work well in Commando engines but were not recommended for the Atlas or Mercury.

Perhaps someone who knows the rules and regs of plug choice can explain the wrongs and rights of an N4 versus an N7Y or similar.

Sorry to throw another fly in the ointment, but what about your mag? If a plug is misfiring it will look all black and oily because the mixture hasn't been burning properly in the cylinder. I went through all this on my 650ss, and even after having the monoblocks overhauled and re-sleeved I still had problems. My mag had been previously overhauled at what seemed a good (cheap price) some time before I rebuilt the ss so I thought it would be fine but having ruled everything else out it was off with the mag and over to Dave Lindsley. He ran a test on it while I waited and declared that it was only running at 10% efficiency. He did a great job, he is not the cheapest but is very professional, gives an honest time for completion and now my ss runs really well. I have also hear very good reports of Dave Cooper when it comes to mag repairs.

I run NGK B7ES which is equivalent to N4

From championsparkplugs.com the following info;

Y = standard projected nose cone, (Mick Hemmings in his write ups advises not to use projected nose plugs).

N4 equivalent is B7ES

N9Y equivalent BP6ES Note P is NGK's designation for projected nose cone and sorry Anna the N9 is a softer plug.

Finally on single carbs -DON'T DO IT there's nothing wrong with twin carbs, if it's not working then something else is wrong. I have 4 classics all on twin carbs, My Commando has now done 92,000 miles, 42,000 since 2007 and it's on twin carbs. Twin carbs are not a problem and are very easy to set up if there is a problem it is elsewhere.

Regards Bob

Bob makes excellent and sensible points. Suspect the magneto! However I must disagree with the last comment. Norton twins don't really benefit from twin carbs in normal use and one carb is so much easier from the idle mechanic's point of view. Finally NGK B7are a good choice of plug.

Bob makes excellent and sensible points. Suspect the magneto! However I must disagree with the last comment. Norton twins don't really benefit from twin carbs in normal use and one carb is so much easier from the idle mechanic's point of view. Finally NGK B7are a good choice of plug.

Well you must not of seen the NGK BR7ET then these are self cleaning and will not oil up has some plugs do and they give a better direct spark, so just give then a try, yours Anna J

Just so that you know a BR7ET is;

B= 14mm

R= Resistor type

E= Thread length

T= 3 ground electrodes

A different type of plug may help, who knows, but it is always best to cure the cause not the effect so I repeat my original comment "what about your mag". I would also wonder my bike won't work on the same single electrode plug as most do. The suggestion of a 3 electrodeplug is probably a good suggestion for a well worn engine but you've just had yours rebuilt.

I could debate Gordon's point re twin verses single carb but at the end of the day it is all opinion and all I can say is twin carbs work for me and I assume single works for Gordon.

Bob

NGK BR7ETis not the plug to use if you have a magneto. As Bob points out, the R means a resistor type. OK for electronic ignition though.

Single carbs work for me, but then I am an idle mechanic. Funnily enough I used to race the Domi on a single carb. Couldn't keep up with an H2 Kawasaki, but then nor could anyone else.

I should add that as your problem is only on one cylinder the quickest and cheapest thing to do first is have a good look at that plug lead, cap and associatedpick up and brush. Have the pick up out and check that the brush isn't worn out or sticking. Clean the slip ring by holding a rag with a drop of white spirit against it and turning the engine over slowly hold it in with a piece of stick or non insulated material - even a sick mag will give you quite a jump if you do it with you finger!

Thanks for all your comments, Everybody.

Regarding Bob's suggestion thanks for the warning about checking the mag and I have fallen foul of that issue in the past. However itâs definitely not the mag as I have a Boyer fitted! I still have the original mag, which I had overhauled by Dave Lindsley many years ago and which has done a very low mileage since, so can always revert to this at some stage if I want to. I could never get the points gap right on both cylinders so the timing wasn't exactly symmetrical, so whilst it seemed to run OK I wanted to try the newer technology and this is what is on at the moment. Plug caps and HT leads are new.

I went out yesterday and did around another 30 miles with no problems of running on one cylinder. Probably because I didn't encounter any long, slow moving queues and in spite of evidently using the wrong plugs. I'll change them for the correct spec very shortly. Still getting some blue smoke at times, particularly if I've had to stop for a minute or two after a downhill stretch when there is a small cloud on setting off again, though I can't see a trail behind me normally. Just need to be patient a bit longer I guess. I did use the engine harder than I had been doing before, in line with previous comments and encountered no problems so that made the ride much more enjoyable!

Regarding Anna's earlier suggestion about changing the engine sprocket to adjust the gearing for my local terrain I've only just managed to get the primary chaincase to seal properly so don't want to dismantle it again just yet! Iâve managed as it is for the last 35 years with this gearing so donât really think thereâs a need to change.

Obviously twin or single carbs have their supporters for various reasons. I intend to see how I get on once the engine is fully run in and then decide whether to revert to a single carb or stick with the twins. At the moment it seems to be doing OK on the twins and I've managed to tune them to tick over reasonably so I'm tempted to keep them. I think the downdraught twin carbs look so much better than the horizontal single unit, but of course you may not agree. Each to his own.

Thanks again for all your comments. I just need now to get out and about for a few more miles and then should be hopefully fully sorted. If not, as Arnie once said, Iâll be back.

well yes do have some fun in the sun wilye it lasts and do tell us what fuel consumption you get with twin carbs , yours anna j