KA100 Sparking but not Starting

KA100 fired up, was going full throttle without me touching the gas. Then when we killed it and tried to start it again, it did not start. Had just went off track into the dirt if that helps. cleaned the carb and airbox.

Is the starter working? If so, have you checked for spark? That would be my first check. If no spark then I would check the ground connection, as well as the connections at the coil and spark plug boot.

If you have spark, then I would double check that all of your carb gaskets were assembled properly, and no passages are blocked.

it does spark i checked for that first

it had been running perfectly all day until i went off in the dirt. What passages should i check?

Was there fuel at the carb when you put everything back together and attempted to refire? Sometimes if there’s an air bubble you can see fuel being pulled along the line towards the carb as the engine turns over…was this happening?

Did you try choking the airbox to pull more fuel into the carb?

The passages I was referring to would be anything inside the carb that was exposed when you had it apart. Usually not an issue if you blew it out with carb cleaner and/or compressed air.

yes fuel at the carb, took apart the carb and cleaned it completely. every thing looked perfect. Reassembled and tried to fire and nothing. Sparking and everything looks fine. I am lost


You may try disassembling the carb again to ensure the inlet needle (needle & seat) isn’t stuck shut.

Couldn’t hurt to throw a new spark plug in if you have an extra laying around. I’ve seen that help KA engines that were running unpredictably.

Do you have access to a remote starter? This is more effective turning the engine over. You could also remove the airbox to ensure it’s not been flooded, and also to visually inspect that nothing whacky is going on with fuel delivery when attempting to start.

Does it not start at all, or does it start but not stay running? We went off track this year and ended up damaging the internals of our gas tank, creating an air leak in the line that would allow the kart to stay running.

If it won’t turn over, you may need to check the onboard starter. The brushes can get damaged, and not allow it to even fire.

Does anyone have an external starter to use?

it does not start at all. it started to drive back to the pits, and it started at the pits once. as soon as it started it revved full throttle and then i killed it.

no external, i was testing the CAKC track with one other person. and dipped a tire into the dirt on the straight (was looking at mychron data like an idiot) but the spark plug fired perfectly. everything looked good. carb looked clean, and so did gaskets

It sounds like there are two issues and since this happened after an off I would think it is related to that for sure. As for the uncontrolled rev I would check to make sure the throttle cable is completely returning to closed or snapping shut to the stop. Also, make sure all the wiring is good and connections are tight. It is possible a lean condition caused this rev, which may be related to your no start.

As for the no start, when you cleaned it did you remove the needles and clean out all of the passages? One fleck of dirt could cause issues. If yes, return both carb settings to 1 and 1 turn out and as others have said prime the carb without the air filter on by holding your hand over the opening. Do you have another carb you could swap out?

if 1 fleck of dirt could cause issues then that is definitely the problem. I had rocks and tons of dirt in my air box. I took off the carb inlet and there were dust particles in there as well. i took it apart and cleaned the gaskets, i wasn’t going to change gaskets because it was the last session of the day anyways. So you think completely disassembling the carb and cleaning the inlet and needles would help? And do you think i caused any damage with that amount of rocks in the airbox

Revving to full throttle is usually an air leak somewhere.

You need air, fuel, and spark to start. If you have too little or too much of any of those it won’t run.

where do i need to look?

I just saw on another post here about the make sure the carb is closing all the way, and i noticed mine has a little gap at the top where the fuel is delivered. I am guessing that is my issue?

well the little butterfly thing is supposed to have a notch at the top, i’m not sure if that is an issue or not, it seems to return to a normal position, but i can’t tell if it’s completely air tight

If you had this much stuff in your air box I would completely clean the air box and filter and reoil the filter when dry. Completely disassemble and clean the carb. I am a fan of using an ultrasonic cleaner. I would reassemble with a new carb kit. Check your reeds too.

Tough to say if the off caused more damage. You may want to check the whole motor over, make sure the exhaust is on correctly, and the head bolts are tight.

As for the butterfly, it won’t completely close or it won’t run. As long as it snaps against the stop you should be okay.

I have also seen a 2 stroke “diesel” or runaway from excess fuel built up in the bottom end, had to choke it out to stop it. Also saw a engine so flooded we had to pull the reeds and pour it out. After that it started fine.

how would i go about getting fuel out of it. there is a possibility it could be flooded as well. Just pull the reeds and dump it over?

Pretty much yeah. 20characters

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