Topic: CB650 Smoke issue

[1979CB650_Chris]

Hey All,

I recently got my 650 firing across all 4 cylinders (had to replace a spark unit) and rebuilt the carbs and synched them. So I take the bike out and it runs like a dream except for..... smoke.  First some history (may be relevent to the current problem), the PO had the bike sitting for 2 years and when I changed the oil, I went to replace the oil filter but, there was no oil filter (so I actually installed one instead of replacing one).  After I got the carbs rebuilt and synched, I got the bike running but had two dead cylinders I did notice something was wrong but I did not realize two cylinders were dead for a while.  Once I found out I replaced a spark unit and got them working.

Ok so my problem is that at idle (after the bike is warmed up) there is occasionally a little bit of what looks like white smoke coming out of the right side exhaust, not a whole lot, but just noticible.  Also if I get on the engine hard and rev above 5500 RPMs it blows blue smoke like a 2 stroke ( Ifeel sorry for the person behind me).  Also after crussing for a while around 3  - 4000 RPMs and I idle there is some more white smoke, not much but its there.  Anyway i think it might be that the piston rings are shot, any other suggestions would be great.

[WiredForStereo]

Prolly the rings.

When you run something with cylinders not firing, especially with an air cooled machine, I think you can get warpage across the cylinders and cause excess wear in them.  Like redlining a cold engine is a bad idea for instance.  I had a SL350 with one cylinder out for who knows how long, and after I got it working, it smoked like a two stroke.

How much has it run since fixed?  You may need to burn out some of that oil that has been building up in there whilst not firing.

Sol

[cb650]

Did you flush out the tank?   Maybe water in it.  If its runnin good ride it and do a couple frequent oil changes.



                              Terry