Popping fouling in town.

[whataulooknat]

My 74 CB 450 is having some trouble when it comes to riding in town. It seems that any speed less than 35 will pop and foul out on the right side no matter what gear i'm in. Sitting in neutral at idle the mixture is correct. plugs look good. and running down the highway the bike also runs great and has plenty of power through the full range of acceleration. Its just running at a constant low speed near 20 to 30 mph that it pops and fouls out only on the right side.

 

[Big R]

What rpm's is it running at that speed? You said all the gears, but I just want to clarify.

Only thing I can think if is a gummy needle, or maybe somehow your carb isn't getting air at those speeds (due to aerodynamics).

 

[whataulooknat]

In between 2,000 and 4,000 depending on the gear. it doesn't do it if i speed up and then slow down over and over just when i hold a constant town speed. or if i sit in neutral and try to hold the rpm at around 3-4,000 it pops and sputters on the right cylinder. It pops once in awhile going downhill too on the highway. Basically anytime there is little to no load on the engine.

 

[Big R]

Wait a minute- does the 450 have CV carbs? If so, could there be problem with the slide/diaphragm?

 

[teazer]

Yep. It has SU style dashpots. No diaphragms to tear but they can get sticky. I'd also clean and check everything in the carbs. Look through all the jets in pairs - are the holes the same? if you spray carb cleaner through them, do they both spray at more or less the same rate?

 

[whataulooknat]

yeah i pulled the carbs apart and cleaned everything didn't notice anything unusual. CV slides seem to be moving fine. I did the ol Run down the highway and kill it while moving pull over and check the plugs. seems the left side is a little lean and the right side was a tad rich They are both perfect at at idle though so its not the idle fuel mixture. I'm thinking one carb is opening a little more than the other with the throttle cable. Which one would it be? the richer one or the leaner one?