SOHC.co.uk Forums > CB500/550

running on unleaded !!

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Johnwebley:

--- Quote from: K2-K6 on June 06, 2013, 09:35:39 PM ---It's quite unusual to break rings on a 4 stroke engine if everything is normal, possibly more influenced by the assembly last time it was built.

Also a possibiltiy if it had been stored for a long time for the bore/rings to rust and cause damage when someone tried to start it.


--- End quote ---

the history,I have owned the bike since 1977,

the barrels have never been disturbed,the head came off about 20k miles ago,after I damages a couple of valve stems while changing
the cam-chain,the bike gets regular use,although only between 2-3,000 a year,

Bryanj:
The old CB/CD 175 and the 250/350 K4's used to do the top ring if they were thrashed a bit too much before they had warmed up----never realy found out why, put it down to differential expansion and warming too quick. If we stripped them quick enough it was just gaskets and rings but if pistons as well normally went 1 size up and rebore as the bore was only a small part of the cost

mickwinf:
haha I remember my old 250k4 doing that, glad it wasn't just me. I did abuse it though!

Johnwebley:
ok,further update,

 new parts arrived from Mr Silver,

 nice new piston,and 4 sets of rings,

slight query,
 the rings are 3pt oil,and two plain rings

one looks plain,no markings,seems to be coated in black teflon ??,guess its the second ring,
and I guess the one with grey surface for the bore is a chrome ring?? and is fitted at the top,

again no markings,

do you agree ??

regards

John

paul G:
John,

I recently had some rings for the 550 from silvers.
The rings are slightly different if you look at them one is square and the other slightly tapered.
It tells you the installation sequence in the manual if you have one, the rings are marked with a "N" this needs to go to the top if I remember correctly.
Hope this helps.

Regards,

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