Topic: CB125s compression issue

[y2kc0wb0y]

Got the bike back together and running. Question: are the CB125 engines on the noisy side normally???

[grcamna2]

Can you give us any details about the top end work that you did to it ?

[y2kc0wb0y]

In addition to replacing the piston and honing the cylinder we did just "basic" valve work seeing the bike only has 600 miles on it. Meaning: We just pulled the two valves, polished, lapped, cleaned the squish/combustion area of carbon and re-assembled per the manual.

[grcamna2]

How did your cylinder measure up? did you use an inside micrometer that gave you accurate measurements all the way up & down the bore of your cylinder ?

[y2kc0wb0y]

Didn't have a meter. Used the compression ring and measured the gap which in ec down the sleeve

[Flying J]

What noise its it making? I rebuilt my 125 and i would not say that it is a quiet motor.

[grcamna2]

Roasted; I wonder what the back story is on this damage. I was able to hone the cylinder wall out so just a finger nails size nick was in the wall. Do you guys think I'll generate a large heat spot here if I leave the nick? The rest of the cylinder looks good.

It's possible the cylinder sleeve could be warped or out-of -round from too much heat in one place and that's causing it to be tight at one point in the stroke of the piston and loose at another point..localized overheating.

[y2kc0wb0y]

What noise its it making? I rebuilt my 125 and i would not say that it is a quiet motor.

Sounds is hard to describe - rattling and a lot of carb roar.