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Has anybody changed piston rings?

theblackorder
theblackorder
Squiddy
Squiddy

Posts : 12

Has anybody changed piston rings? Empty Has anybody changed piston rings?

Post by theblackorder on Thu 25 Jul 2019, 9:42 am

Hi folks! My CB500 X 1999 with 45k miles on the clock is burning engine oil for the last two years. I changed the valve stem seals also changed the coolant and flushed the radiator as one thread here suggested but to no avail. So the next logical thing to do is replace the piston rings. I didn't find a thread on this topic, so has anyone done that? Any advice would be helpful. Looks like the original piston rings are RIKEN as most Honda OEM piston rings. I was hoping that these rings can be bought directly from RIKEN instead of Honda OEM from the dealership, but cannot find anywhere on the Internet. Also do you think I should buy a set of standard rings and not oversized, as I am not planning honing of the cylinders. This is what I can think of now but for sure more questions will arise later. Cheers!
ANDYC
ANDYC
the 900
the 900

Mechanic
Posts : 1105
Location : Windsor

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Post by ANDYC on Thu 25 Jul 2019, 10:29 pm

Firstly does it need new rings?
How much oil is it burning?
Are you sure that it's burning it and not ejecting it into the airbox
And what oil do you use?
45k is not a lot at all for these engines if they are well maintained. 
If you have a broken ring then it will probably have damaged the bore, so a rebore to overcome any damage will be necessary or you will have the same problem. 
If for some reason, unusual but not unheard of the bore should have worn oval then, again a rebore would be necessary. 
You can't use oversized rings with std pistons I'm afraid, those days are long gone. This would probably result in rapid wear at best or a seizure at worst. Neither of which would help to solve the initial problem.
As a thought,  have you had the bike from new?
To get a better idea on the actual fault, do a compression test or better still a leakdown test, as that would give you a good starting point. Do one as normal and then do another test after putting a little oil into the cylinder to seal the rings.
If there is a big difference between the two sets of readings, then the rings may be the culprit.
It would be far easier to test it first before stripping the engine unnecessarily.
theblackorder
theblackorder
Squiddy
Squiddy

Posts : 12

Has anybody changed piston rings? Empty Re: Has anybody changed piston rings?

Post by theblackorder on Fri 26 Jul 2019, 11:57 am

Okay. I got the bike at less than 10k miles about 10 years ago. I have been using Motul 10W40 semi syntetic. For the last 2 seasons I've been adding 100 ml of oil per 250 miles roughly.  This season I installed k&n air filter and yoshimura exhaust two weeks ago, hoping that it might help with carter gases pressure or something. With the original air filter it was a bit oily in the air box. With the k&n it's a bit more oily so I put the yoshimura two weeks ago and changed the motor oil to Bel Ray 10W40 semi syntetic. The bike runs fine, it has good power. When a friend of mine was riding behind me on the motorway, he told me that twice it happened to cough out black cloud out of the exhaust. When it's idling the exhaust gases are clear -  nothing black or smelly, although there is black carbon deposit in the exhaust pipe. Last time I took the tank out, the cylinder head cover was oily and it looks like that's from the head cover hose clamp. Is this giving you any clue? I think as well that the millage isn't high at all for the piston rings to wear out.
motofan
motofan
Three's a Charm
Three's a Charm

Posts : 145
Location : Normandie, France

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Post by motofan on Fri 26 Jul 2019, 12:32 pm

Hi, can I add my twopenn'orth here?
Black smoke is usually rich mixture, blue is oil. Andy will know better than me but if the engine is sucking oil in from the breather would that burn black? I think judging from the oil around the breather pipe could your bores be glazed thus pressurising the sump too much and pushing oil vapour into the breather? As you've removed the head before to replace the valve oil seals could you do it again and bust the glaze with some emery cloth or before that put some cheap mineral 10w30 in the motor and ride it for 500 miles or so, that might bed the rings in without taking the top off the motor.
As Andy says, at your mileage and reasonable maintenance the rings shouldn't need replacing!
Hope this helps, Dave.

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