Hi Guys, since I have come to the conclusion that I have worn rings in my bike,
and as I am no mechanic but happy to give replacement a go, I am wondering if I am likely to be able to replace the rings with the original size and not need the bores re-honed at all to solve the issue?. My compression test shows "ok" at best and all even pressures. The bike goes well (80+kms on the clock) but has had a very hard previous life. No blue smoke noticeable at all, but does go thru the oil quite quickly, regular top ups necessary.
What do you reckon?

 

It really should be blowing blue smoke if you have high oil usage with no oil leaks, the only way to see if it needs a rebore is to inspect the cylinders for scratches damage etc.


A borescope down the spark plug hole may show any damage.(borescope under $15 on ebay)

 

Higher than normal oil consumption. It must be going through the combustion chamber. unless theres a pool of oil under the bike. Even if the compression is about average, the oil ring, is not designed as a compression ring like the others, so either a honing of the bores, or the oil seal caps on the valve stems could be hardened. Either way, its a partial engine strip down.
Understanding you are no mechanic, you could buy a 2nd hand engine, cheap, and practice on that in a methodical way.
If you do end up doing the engine (yours), its head off, sump off, and you can keep engine in frame, and remove con rods with pistons, but if you really are not confident, it a mechanics job with a good work ethic.

 

Once you get the head off, you can determine if the bores need attention. You will need to measure them to make sure they are perfectly round, not tapered, and within service limits. This takes special measuring tools to do, as it needs to be very accurate. If they are within spec, then you can use a hone to clean up the wall surface.

With that mileage and an oil burning issue, I wouldn't expect to find them in perfect shape.

 

How have you come to the conclusion your rings are the issue?

 

My conclusion was just basic engine knowledge really..the compression is just "ok" when I tested before total bike (not motor,but was removed to sandblast & clean) tear down to do up/repaint etc...and there are no noticeable leaks around at all to justify the oil use. If you think there should be other tests worthy of trying to determine or otherwise please do tell..I am happy to do them, confirm 84.000KM's on the clock and a hard previous life. I am using 20/40 (Havoline) fully synth bike oil which may or may not be a good nor bad thing, but oil types, viscosity etc seems to be quite a manufacturers 'secret" topic from what I can see.
Great to hear if I should be checking other stuff first tho....
Cheers
Peter.