Too Rich or Too Lean

[Stretch9301]

The idle speed screw? Yes, Ive tried it, doesnt seem to help...

Its got 22,7XX on it...

Yall think it could be a valve problem?

[93gc40]

Originally Posted by Stretch9301

How do you tell?

I (finally) got my VT500 running again (thx for the replies, BTW), but now theres this weird popping noise coming from the exhaust.

It's random from 3-5k rpms and sporadic, but anywhere 6k and up its like someones making popcorn, very steady and rhythmic. They are much louder on deceleration, where they're noticeable at ANY rpms...

These pops are NOT loud at all, but they still bother me. Something isn't right.

I looked at the spark plugs and they're kinda black, defiantly not white.

What causes this? BTW the bike still has its stock exhaust, although I drilled some small holes in the baffles.

Extra-special bonus information:
The last owner wallowed out the jets in an attempt to get more power, then sold the bike to me cheap because it wouldn't run right. I replaced the jets and it ran 100x better. Is it possible there are still more bad repairs in the carb or elsewhere in the engine that need to be fixed?

Any thoughts appreciated...

In red, is your problem. Simple lean VS Rick test is WHEN the pops occur, if on decel or idle, lean, if on acceleration or at speed, more on the rich side. This is not a diagnosis, but a sign on where to start looking. The best place to look to determine AF mix is inside the cylinders, what do the plugs look like. Start with verifing compression and ingnition are in spec, this old a bike the issue could be a weak coil or plug wire. Or flat piston rings, heavier oil might help, or new set of rings. Could also have a lot of carbon build up, due to the wollered out jets. I would definatley look at rejetting, just determine your level of modification and order a set from Carbjetkits. This is the most likely fix, in the end.

[93gc40]

Try an ULTRA dose or seafoam, to try to break the carbon loose. 1 gallon of gas and 1 bottle of seafoam, go ride for at least 30 miles, smooth and easy, ignore the smoke, when you return let sit for 1 hour, fill tank with clean gas, go for another ride this time you ride HARD. By hard I don't mean fast I mean, high revs, Hop on the Freeway wind it out to speed limit in 3rd, and stay in 3rd there for 10-15 minutes. Goal is to keep the revs HIGH.

[93gc40]

Whats the voltage in the battery????

[Stretch9301]

Okay, thanks!! Its already running OEM stock jets, I replaced all four of them.

I'll buy a bottle of sea-foam tonight...

My buddy thinks its a sticking float valve, thats just not getting gas in one cylinder, or maybe just not enough gas?

What do you guys think? Thanks for the replies

BTW, I just put in a brand new battery. It has this problem RIGHT after coming off the charger, and/or when I jump it from my truck...

[justinmahn]

Good job on the new parts, they'll make your job much easier. Unfortunately you now have to reset the carb from scratch on the tuning procedure. Do you have access to a shop manual?

Why would a float valve effect only one cylinder?