this problem started after cleaning out my carb, i think the dirty carb was causing it to run lean, which made it easier to ignite the fuel/air mixture, it was plugged up BAD!

anyway i replaced the spark plug, rebuilt the carb and even put a brand new ignition coil on it which that helped some, as of right now the ATV starts up fine cold, and it will run fine for 10 or so minutes of mild driving around the yard, but as it warms up the idle slows and then stalls, once it gets this hot, it will NOT start back up until its cold.

i replaced the spark plug while it was hot and wouldnt start and then it will normally start back up, but after it cools down i can put the old plug back in and it still starts up fine, the replacement plug will not fire once its hot either.

at this point my only taughts are the CDI box, or maybe the valves need adjusted, or i guess it could be possible that its running rich and loading up.

does anyone have any suggestions? ive been throwing parts at it but im not getting any results.

matthew

clean your air filter?

quote Originally posted by pokeyfiero: clean your air filter?

and/or to much fuel?

Did you adjust the air/fuel screws?

quote Originally posted by avengador1: Did you adjust the air/fuel screws?

there is only one screw in the bottom of the carb, im not sure if it should be screwed all the way in, all the way out, or what, right now its exactly one turn from all the way in.

airfilter is clean.

i really dont know what the proper way to adjust the air/fuel screw is, or even if thats what that screw does.

i guess there are technically two screws on the carb, but ones just a bleeder screw for the bottom of the bowl to make sure there is fuel in it, and i definatly have fuel even when it wont start, the float is NOT sticking either.

matthew

bump

What color is the plug right after it stalls? Is it wet with fuel or dry?

Fuel, Air, Spark

That's all you need (properly timed, of course) to run your engine.

Air You said the air filter was clean, so that takes care of that.

Fuel Can you smell fuel when trying to start it when hot? Can you get access to actually see if fuel is sprayed in the carb when you move the throttle?

Spark Pull the plug, re-connect it to the lead, and see if it sparks (best done in a dark area), If no spark, replace plug, if still no spark, replace lead, etc--keep working your way up the ignition...

These would be my recommend troubleshooting steps.

------------------
86 Fiero 2.5L, 5spd.
00 Ford Focus 2.0L 5spd
66 Chevrolet C10 250 cid, Powerglide
04 Suzuki GSX-R600

when i remove the hot plug, the end of the plug looks sooty, not alot and it still sparks fine when i crank the engine over with the plug out, im honestly at a loss, thinking maybe the valves need adjusted or something, but im really not sure, like i stated it runs great for 10-15 minutes, then the idle slows and dies, then wont start until its cool again.

matthew

Having a sooty plug doesn't jive with running lean but it does sound like it is getting really hot. This is exactly what can happen if you run an air cooled engine lean.

If it were running rich then it would die in a minute or so after starting not 15 minutes.
Vapor lock in the fuel system from heat maybe or a clogged vent line.

Does the carb have the throttle cable running into the top of it?
If it does it should have an adjustable needle that regulates fuel.
Try raising that up a notch if it seems to be running too lean.

quote Originally posted by m0sh_man: when i remove the hot plug, the end of the plug looks sooty, not alot and it still sparks fine when i crank the engine over with the plug out, im honestly at a loss, thinking maybe the valves need adjusted or something, but im really not sure, like i stated it runs great for 10-15 minutes, then the idle slows and dies, then wont start until its cool again. matthew

Sounds like a lean condition.
Do you have any jets for your carb? I'd go up one size on the main.
Like we say at the track, The machine ran the strongest & fastest it ever has... right before the piston melted.
In my race ATV I use NGK Iridium plugs. If I get into a lean condition the electrode of the plug will melt before the piston. Its cheap insurance. I'd rather melt a $14 plug than detonate a piston. ( a custom cut one at that)

------------------
86 GT
87 coupe restoration project.

quote Originally posted by pokeyfiero: Having a sooty plug doesn't jive with running lean but it does sound like it is getting really hot. This is exactly what can happen if you run an air cooled engine lean. If it were running rich then it would die in a minute or so after starting not 15 minutes. Vapor lock in the fuel system from heat maybe or a clogged vent line.

ill get back with you there pokey, the heat thing is definately going to cause me problems, and i think ive pinpointed one of those heat related problems, The fan isnt working, or atleast i dont think it is, of all the time ive ran it the past weeks i dont recall the fan ever coming on, so im taking the front plastic off now so i can test the fan out and see if its working, but i dont think it is.

i took it down to the creek today and played around, it ran great all the way down to the creek (about 1/2 mile all down hill) ran good while it was in the creek, but as i was coming out there is about 1/8th mile of a 15-20% grade, and im pretty sure that heated it up pretty good cause after that it was not reving well and sputtering when i gave it gas, atleast i made it home before it quit. i removed the spark plug immediately and noticed it was not quite as sooty as before but it was still sooty, it wouldnt start at all after i shut it off, it was getting good spark though, i tested that, so i put a new plug in it and it still wouldnt start so i let it sit, came back 2 hours later, turned the key, hit the start button, fired right up without any problems.

but in my 1.5-2 miles of riding it the fan never game on, its liquid cooled also, and from what i can tell the waterpump is working fine as the radiator seems to have plenty of water movement.

matthew

I had the same problem on my Yamaha Timberwolf...stalling and running poor after warming up. After you run it a while take a flashlight and look in the gas tank. look for debris floating around. The fitting in the bottom of the gas tank might have a screen on it and is getting plugged after running awhile. That is what happened to mine. Good luck.

Steve

Well the fan wasnt the problem, drove it another 1/2 mile today and when i pulled into the garage it stalled and wouldnt start back up, went back an hour later and it runs fine after cooling down.

im having a ATV tech look at it monday, he specializes in ignition/carb tuning, so hopefully he'll figure something out on it.

matthew

is your choke on

no seriously maybe its not adjusted right or something?