Hello,
Hope someone here can help a me out. I have a 2001 KLF300 Bayou 2 wheel drive quad. It is all stock and no modifications were made to it. I have a Clymer manual for it and exhausted all fixes it has supplied already. I checked timing and valve clearences, ignition, cleaned air filter and carb. all the jets are correct according to the manual. Here is the problem; it starts easily with the choke when it cold and with out the choke when it is warm outside. When you give it a little gas it dies. If you feather it gently and play with the throttle sometimes you can get it to rev out and run fine until you let it drop back to idle. The manual says the air screw should be at 2 1/8 turns out but I find it runs better at 4 1/2 turns out. That leads me to believe the jetting is wrong. So here are my questions....
1. Is the starter jet just there for the choke system?
2. Would I go up or down in size of the pilot jet, main jet or both?
3. What would cause a good running machine to get so far out of jetting specs?
4. Any other items I should look at?
Compression is good also according to the book and oil isn't overserviced.
Thanks for you suggestions. Rob

 

I would not change/adjust the factory spec of the carburetor settings to make the quad run better. Just double check what you have with following:
Main Jet: 125
Needle Jet: 6
Jet Needle: N74T
Pilot Jet: 38
Fuel Bowl Height: -0.5 +/- 1 mm
Aire Screw: 2 1/8 turns out

Your problem description (stalling when throttle is opened up) sounds like the high speed circuit of the carb is clogged up by debris or varnish, not letting enough fuel to flow. Also, read the spark plug which may give you some clue.

 

The spark plug looks good. Nice golden brownish color. It is a new plug and runs great in the higher RPM's. Carb is completely clean and no dirt or obstructions in the carb or fuel system. Fuel flows good through the petcock and out the carb drain if opened. Choke and butterfly operate nicely. No tears in the slide rubber boot and all parts in the carb are what the manual calls for. Any other ideas?

 

Do Carbs just go bad and need to be replaced? I still can't get it going with jetting changes. Any ideas?

 

Common problems to carbs are:
1). Dirt/varnish built up blocking fuel flow.
2). Rubber parts aging/deterioating.
3). Metal corrosion (especially between brass and aluminum).
4). Incorrect adjustment/parts.
There are no metal parts that actually wear out because of too much usage. Carbs generally go bad due to un-usage - just sitting for too long. Carbs are generally rebuilt not replaced.