Hello all, as you may know I was in the process of rebuilding the top end of my cb200. I got the head professionally cleaned and valves lapped. I installed new piston rings, new gaskets, including head gasket. Cylinders honed. I got the bike fired up and running for a day. It didn’t run too well but figured it needed carb tuning.
To my disappointment, while riding the bike had the same problem as before the rebuild, it would bog out and misfire at like 7k rpms and then it died out entirely, needing to be pushed home. After that I tried starting the next day and it didn’t want to start. I finally got it going and I noticed blackish smoke out of right exhaust. It also filled my garage with a smell. Im not sure what it was but it didn’t smell good. Anyway the bike wouldn’t idle and it ran horrible. Like it was completely strained.
So now I pulled the motor again and checked the smoking cylinders valves, the exhaust valve and port is completely black. The other cylinder is still pretty clean with a little black. What does this indicate!?!? Mind you this head was completely pristine before the first start. And compression read below 60 for both cylinders.
To my disappointment, while riding the bike had the same problem as before the rebuild, it would bog out and misfire at like 7k rpms and then it died out entirely, needing to be pushed home. After that I tried starting the next day and it didn’t want to start. I finally got it going and I noticed blackish smoke out of right exhaust. It also filled my garage with a smell. Im not sure what it was but it didn’t smell good. Anyway the bike wouldn’t idle and it ran horrible. Like it was completely strained.
So now I pulled the motor again and checked the smoking cylinders valves, the exhaust valve and port is completely black. The other cylinder is still pretty clean with a little black. What does this indicate!?!? Mind you this head was completely pristine before the first start. And compression read below 60 for both cylinders.

