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Old 11-27-2013, 06:59 PM   #1
R-dubb OP
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Joined: Aug 2001
Location: San Francisco
Oddometer: 4,969
R90/6 top end overhaul

I'm restoring a bike I owned 35 years ago. I had the heads redone by SJBMW when the motor had about 40k on it. It now has 30k more and has been sitting some. Compression is at 115/120 cold without carbs. That's a little low. There is also some oil getting to the plugs, but no smoking except on hard acceleration. The bores are clean, but pistons seem slightly loose. Heads look just like they did 25 years ago but for some carbon.

I'd like to hone and fit new rings. Does anyone make oversize rings? Or, do I need to buy bigger pistons? Haven't taken measurements yet to see if the bores are straight. Pretty sure they are as nothing is visible that would indicate uneven wear.

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