I've got an outlaw sprint kart with a kx500. It runs ok at first but when it warms up it boggs and dies and won't start back up untill it cools back down. I've tried everything I could think of... I've put in a new coil, new stator, new plugs, rejetted the carb and installed a dial a jet. Still couldn't get it to stay running so I took it to a local dealership, they've had it for two weeks and still same problem. The mechanic said that all resistances are good cold and warm. I found out the hard way that it's getting spark!! He seems to think that it's maybe a fuel issue. This thing will vibrate your eyes out of your skull, but we've got a bracket holding the carb also packed foam around it for isolation but still same problem. My question is... when it gets warm, could the rotor be expanding enough to crate too much gap between it and the stator? and how much gap should there be? When it's died, Ive checked and found no spark but the mechanic said there is. They have had 4 or 5 guys working on this for 2 weeks now but still nothing found. I don't want to keep throwing $300.00 -$400.00 parts at this thing. Any info would be a huge help.

 

Welcome to the forums. Years ago I had a motor that would do that but it was the valves that were getting hot, expanding and getting stuck. A quick cool down and it would start back up and run for 10 minutes and repeat. But you have a 2 stroke motor, so I don't have a clue, unless the rings are broke and causing the motor to run tighter and slowing it down, but that seems backwards because a broken ring would give it less friction. Sorry I'm just throwing out random thoughts. Someone on here might have an answer soon. Again welcome and have fun. I am very interested on the answer to this. Peace.

 

I've checked and the cylinder bore and piston both look good and this thing has ungodly compression. I think it checked 190 -195 lbs. The transmission doesn't even have 1st gear and if I don't have it 3rd or 4th gear it won't even break the tires to start, it just slides them.

 

How do you even start that thing on a kart? Does it still have the kick or what?

 

Nope, everything that can be removed for weight has been. Can only be push started. Almost EVERYTHING except for the frame is aluminum. It has a Kirkey ultra lightweight seat and all brackets, wing slider and adjusting handle have all been drilled. The horsepower to weight in this thing is unbelievable and it is FAST!! On a 1/4 mile dirt track, it will carry the left front from mid 1-2 and 3-4 all the way down the straights. If you really want, you can slide the wing all the way back and carry both front wheels and drag the back bumper all the way down the straight away.

 

Sounds like a blast!!! You'll have to post up some pics of the kart and the races. You got a photobucket account?

 

No porting/polishing, or other engine mods correct? What fuel are you running? Any milling of the head for the 190-195 psi compression? (105-164 stock) carbon build up will also cause overheating problems.

Have you flushed the engine and radiator? Checked the radiator cap? (18 psi), Have you checked the impeller?

Good luck and welcome to KF

 

Not an "over heating" issue. Engine doesn't run long enough to even get hot. It has been ported and polished and head has been milled. I'm running 40:1 93 octane. Has aftermarket exhaust and flat slide carb.

 

Hey!! Got 4 more of them flatslides????????

 

ok, I get it now. lol

so what is your first impression? You think that it is binding? (what piston, ring, and cylinder are you using?) or you more after the fuel possibility?