KX 125 won't start have tried everything

Ok I need some help I have a 99 KX 125. My buddy has a KX 125 and I was riding it and it died on me. It hasn't started since. we have gone through the manuel and tried the suggestions in the troubleshooting guide. The carb is getting fuel but it won't leave the carb. The bikes compression is good, we have cheked the jetting, replaced the sparkplug, tested the Fuel Cut valve, we are starting to think it maybe the capacitor, not sure what else it could be any suggestions? Has had a lot of motor work recently prior to this ride.

Do you have spark ? Are any jets blocked ?

Air + Fuel + Spark + Compression = ignition

IF the carb is getting Fuel but it is not getting into the cylinder, I would check the AIR. bad reeds may cause a loss of velocity.

It could also be bad compression but you state that the fuel is not leaving the carb.

rip apart the whole intake and clean, inspect and reassemble.

easy test for the ignition is to get a buddy to hold the sparkplu against the engine block and then give the bike a gentle kick over.

DO NOT hold the spark plug itself, I realized this after I picked myself up 20 feet away from a bike when I was 13 :lol:

DO NOT hold the spark plug itself, I realized this after I picked myself up 20 feet away from a bike when I was 13 :lol:

SHOCKED into reality @ 13.:lol::busted::worthy::banghead:

J/K man.That is a great bit of advise however and one that I should have been aware of @47(last year) as I was messing around w/my lawn tractor-I turned the key,spinning the starter as i was arcing(misspelled?) the plug holding it in my bare hand.DUH.

it was a moment of clarity that had escaped me over the years I assume-

The pilot circuit is plugged. How much compression did you have on the test?

we did the spark test while on the trail and it sparks. (luckily we knew not to hold the spark plug so we didn't set shocked)

The jetts are brand new could they still be bad?

I don't know about the compression test i'll ask my buddy.

You did turn on the fuel right???

Yeah the fuel is on

we did the spark test while on the trail and it sparks. (luckily we knew not to hold the spark plug so we didn't set shocked)

The jetts are brand new could they still be bad?

I don't know about the compression test i'll ask my buddy.

someone dumped in your gas tank when you werent looking im tellin you man thats always the problem
or theres a poop in the carb blocking everything:ride: :foul::banana::bonk::p:moon::lol: :lol: :p:banana::foul::lol::moon::lol::mad::ride:
Yeah the fuel is on

Pretty much worthless advice here.

I would check the spark quality. Fat blue spark. What was the compression reading?

Check the reeds, they may be split and/or missing pieces.

Another thing to look at is crank seals. If they leak, it will run lean and be hard to start.

Have you tried push starting it?

DO NOT hold the spark plug itself, I realized this after I picked myself up 20 feet away from a bike when I was 13 :p

I just learned this last night, its not cool. I was holding a metal table with my other hand also.

we haven't tried to push start it yet. I never thought about giving that a try. We won't be able to get to it til wed but will update when we give the push start a try.

Just a quick thought.

when you say fuel is getting to the carb, do you mean that the fuel runs through the fuel line, or is the float bowl filling with fuel?

you could have a situation where the float bowl is not filing.

have you torn the intake apart and cleaned it.

and Yes I mean from a clean air filter to a carb disassemble and cleaning, verify the carb is set to stock, the jets are in properly and not clogged and that you are at base settings for the area (or at least factory settings).

as said, the pilot cicuit. otherwise, you said it has compression. How much though? does it feel like it has compression or did you actually test it. At 90psi, it'll feel like good compression but 95% chance it won't start. Do a legitimate compression check then let us know and we might be able to narrow it down a little better. Also check for any gaps in the reeds against the block.

Fuel is getting to the bowl.

if its the compression what would be causing that? I don't know much about 2 strokes. My friend told me though that he had it in the shop a month prior to our ride for a leak in the the water pump. They did a compression test while it was in the shop and it was fine and they also replaced the jetts then. Is it possible that the jetts can go bad at one ride?

what was the compression ? it should be about 160-190. 175 is prime.

the compression was at 170.

The compression WAS at 170 but what is it now? You need to test it now and not rely on what it WAS. You can get all the fuel you need with a fat blue spark but with little to no compression it still won't run. Push starting a bike will run with low compression. It needs to be 100PSI + to be able to kick start. If you test it and get a reading above 100psi then the pilot jet is plugged.

it WAS at 170 when we tested it yesterday

You may be getting spark yes, but check your timing and make sure its spot on. it may have came loose.

tear down your carb and verify everything is clear, this only takes 15 minutes or so.

another thing you can do (if you have a spare reed to carb adaptor, dont do this with your only one) tie in a vacuum gauge and kick it over with the throttle shut, if you have vacuum you will know you dont have a major air leak.

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