• Enter the March CB750 Supply gift certificate giveaway! It's easy... Click here, post something, and you're entered into the drawing!

79' CB750L fouled plugs after carb rebuild

Staubig

CB750 Enthusiast
Messages
47
Reaction score
0
Points
6
Location
United States
Alright guys, I'm new here and excited to get put to work with all your solutions. I recently bought a bike, my first, a 79' CB750L. It needed a carb rebuild, which was a pain. I rebuilt the carb, replaced the air cutoff diaphragms and float bowl gaskets as well as the jets. I'm not sure the new jets were the same as the old, because I'm an idiot. I reinstalled the carb and turned her over. Now the bike only runs on (seemingly) the 3-4 cylinder, if that. I was getting weak exhaust from the left side. The bike won't even start now. So I pulled the plugs and they're black as night. I'm not sure if they're firing. Could the reason for fouling be as simple as the rejetting, I wouldn't think it would matter much considering it starts on the idle circuit. Please let me know how I can slim this down to one culprit. Much thanks!
 
Is it possible to drown spark plugs. Or drown them till the foul so bad they won't fire? Is putting the old jets back in and (if needes from there) pulling the air screw out a few turns a possible solution to the problem?
 
its not that complicated. i havent fooled with a 79 lately but earlier models. you have got to have to correct jets or close, reset the air idol misture start at the base sitting,new plugs, make sure you got good gas and a good fuel flow go slow and research if you dont know
 
Thanks! I've gotta double check to make sure I've got ignition after work today. I bought new plugs and am definitely going to reinstall the old jets. It should idle though, since I'm only running off the idle circuit. Correct? She won't even start, tries but won't keep chugging.
 
Stock airbox with filter installed, I checked all the boots when I put the carb back in, but a double check can't hurt. I KNOW its all attached though, worst case scenario there's a leak, which I don't think likely.
 
Side note: after some research the fouled plugs might be from me running the bike with the choke on for too long. Which is very likely. Not eliminating the problem, just giving a potentially different angle.
 
SOLVED

The plugs were black from the choke and only running off of 2/4th cylinders. The ignition coil for 1&4 was bad. Thanks for the help guys.
 
Back
Top