engine rebuild parts

[catbed]

im going to rebuild my engine this winter. long time away but i want to be prepared. reason im doing it is low compression. heres a small list of what ill be doing:

-replacing piston rings
-cylinder hone
-valve stem oil seals
-possible engine repaint
-possible frame repaint

should i replace the piston pins and circlips? i probably wont be taking the pistons off. also, is it possible to repaint the crankcase without splitting the cases? just mask off the openings?

[Nessism]

How many miles on the engine? If it's alot, you might have to bore the cylinders instead of reringing. Only way to know is to measure the cylinders...(read my signature).

[catbed]

8400 miles. dont understand the low compression. rings have had plenty of time to seat. replaced a bent valve not to long ago if you recall.

[80GS750]

did you just put new rings in???

are you getting blowby? oil being burnt with the exhaust?

you dont have to replace wrist pins or circlips if your leaving the pistons on...

[Nessism]

8400 miles. dont understand the low compression. rings have had plenty of time to seat. replaced a bent valve not to long ago if you recall.

Sorry didn't remember the business about the valve.

8400 miles is not much, bores should be good. Bummer about the compression. Are you sure it's not another valve?

[catbed]

no i didnt put in new rings, i took the cylinders off though. its not another valve because the compression is around 120 on all four. no blowby and there is a little smoke when i rev it to higher RPM in neutral. around 6-7k. there was only one time i saw it too.

[chef1366]

120 is good. Ride it!!!!

[Nessism]

Just my opinion but 120 is closer to OK than Good, and not to be confused with Excellent (150+ psi). Agree with the Ride it! part. Put some good hard miles on the engine and see if the rings bed in some.

BTW, did you test compression with the engine warm and at full throttle? (asking just in case).

[catbed]

yes i did do the compression test warm and WOT. guess i wont worry about it until winter. see what its like then.

[doctorgonzo]

That's what I'm doing, hanging on til winter. I have 120's all 4 cylinders and a little blowby. Hard to see most of he time, but i see in on occasion. It's going down to the frame this winter.

[cranemonkey]

I have 5 brand new circlips in the package #09381-16001. $10 and they will be in an envelope tonight...

[psyguy]

with that mileage and those compression readings... just ride it...
but if you want a winter project... well, that's another story :-D

[flyingace]

8400 miles on the engine and you replaced the rings? Why? Or did you mean 8400 since some rebuild event?

I will comment on the 120 PSI. Try a different gauge - I found a more accurate gauge to be 10-15 points higher than what I had been using. Besides that, 120 is not so low as to warrant a rebuild. It may sit at that reading for many Ks of miles.