All,
I’ve got a smoking condition with my bike. I have a 77 CB550F. I rebuilt the carbs last year with no real road time on them. The carbs have been clear tube set but have not been vacuum sync'd. Also, the bike starts with choke on but within 15-30 seconds I have to turn to half or off. The smoking described below came around a few months after rebuild installation. It wasn’t there initially after build.
When starting my bike it pops(backfire) & misses. It gets better as it heats up. The idling increases to about 2,500 rpm. I pull the gas and release to get it back to 1,100-1,200 rpm. Over time the popping stops but the random miss still there. While warming up the bike starts smoking, getting progressively worse. At 8 mins it’s so thick I can’t see my house from the building in the back yard. Once I forgot & left it running for about 15 mins. It’s a wonder the neighbors didn’t call the fire station. It didn’t get any better. I cut the bike off. I noticed a black wet spot about the size of a dinner platter near the muffler to tail pipe joint. I thought it was oil but the wetness evaporated in a few mins. The floor was stained but not coal black or slick/wet.
Initially when the bike starts there is no smoke. At 2 mins smoke is visible but you have to be watching for it. 2-4 mins it’s about like a cigarette. 4-6 about like a normal outdoor grill. Between 6-8 it get very noticeably thick, grease fire.
Yesterday, to confirm if the gas spot was coming from the tail pipes / muffler or not. I routed the over flow tubes off the driver side of the engine. I fired up the cold bike. It started and ran as previously described. There was leaking from some of the overflows. Carb 3 & 4 didn’t leak. Carb 1 on/off dribble. Carb 2 dribbled, then flowed, then blasted, then stopped. The cycle took about 15-20 seconds and would start again. Dribble, light flow, a single water hose blast, then nothing. What I notice was after about 8-10 mins the bike hadn’t started the super thick smoking. It got as bad as a normal grill maybe but nothing as heavy as before. My theory, my original routing of the overflows were restricting the heavy leak of carb 2 causing it to back up into cylinder and eventually out the tail pipe, if that’s possible.
So I said all of that to ask, any one has any idea on carb 2? I’m also thinking the remaining smoke could be from lack of syncing. Sorry so long but was trying to be thorough.