I have a stock 01 quadmaster 500, but this question probably is general to all bikes. I put a K&N filter on it and I'll be ordering an Outerwears. I noticed the other day it was backfiring a lot and almost stalling but feathering the throttle brought it back. It did this only at the higher speeds. It did it again when I got home fishing but hasn't since. I don't believe it's bad gas since I only buy high octane from Shell and I'm extremely careful when filling the bike.
The last two tanks I ran through it have been at low speeds trail riding with my daughter.

Could two tanks of gas cause that much carbon build up?

Can just changing an air filter affect my bike?

Is there a screw on the carb that may be adjusted if this were to be the problem?

What should the spark plug look like if it's too lean or rich?

Thanks for the help,

 

Depending on how restrictive the old filter was, a K&N can lean out a motor, with all the extra air flow, do a run at full throttle, hit the kill switch and coast to a stop, then pull the plug, if it is tan or brown,you are fine, if it is gray or whitish, you are lean on the top end, and either need to jet up one size on the main, or lower the needle clip a notch to get more fuel on the top end. Backfiring is a good indicator of lean condition,you are getting a little hot from running lean.

 

I tried what you suggested, and when I removed the plug, it was black around the threaded area, but the electrode and tip were grayish/brown. It is a NGK plug so I went to their website to check for what the gap should be for this bike, and it turns out the bike came with the wrong plug! Their site says to use a CR6E, and I had a CR7E in it. How much difference does this make? I filled the bike with regular octane gas and installed the proper plug and the problem seems to have dissapeared! Maybe it's my imagination but it seems to be a little more responsive out of the hole. I've been thinking about trying a jet kit, but I'm paranoid of blowing something.

Does anyone know what type of mileage I should be getting with this bike? It seems awfully hard on gas for a 500.

Thanks,

 

I have a 2000 Quadmaster. Mine seems good on gas. I can go allday to a tank easy. How fast does yours go. Mine will hit about 55mph on the street. Have u had any problems with it? When I bought mine it had a CR8E plug in it. I put the CR6E like you did.

 

I think mine would go 55mph on the ashphalt. We live on a farm with gravel roads, and I can do 50mph on it. No problems so far but I've only owned it about a month or two. This hesitation thing is the only recent development but I think it seems to have dissapeared. Hopefully for good. I can probably go a full day just leisure trail riding on a tank, but when I was playing in the gooey muck the other day I burnt close to a half tank in about an hour. I'm planning on putting on a set of Mudlite XL's next week. I'll keep the factory width but go to a 26" instead of 25". It seems to have a lot of torque, I'm anxious to pull a moose or bear with it next hunting season.

Good luck with your bike

 

Am I too lean? yep, you need to gain some weight