'96 KX250 not starting well - fuel related?

[crispy]

Hey all I think I may have an issue with the carb on my 96 kx250, could be the float level or maybe the engine is just worn out as hell. Kicking over it doesn't want to run but as soon as I put fuel down the bore with plug out, I kick it over with full throttle (yes that's right full throttle no choke) it eventually starts. Runs fine when it's going but I think I may either have an incorrect float level or maybe the engine isn't sealing too well and not allowing the fuel mixture to get drawn into the engine properly. Carb is clean and I bought this with the owner saying it stopped on him, so maybe has a blown head gasket to throw something else into the mix. Has 150psi kickint over cold, plenty of spark and it's a nice bright blue spark

[crispy]

When I first got the bike I took the carb off and cleaned out the jets and passages, bowl and everything was nice and clean, no excess amount of gunk unlike my 89 kx250 when I got it. Maybe the float isn't set correctly, it did idle with just the choke on which it doesn't do now once you kick it over, only tries to go on full throttle. I've tried the lean it over then wait and kick over.


Is this more a case of being a worn barrel which needs replating? I'm yet to pull the head off to check the O rings, but what would I look for to see a tell tale sign?


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[ktm84mxc]

Could be a host of problems , head gasket normally means white smoke[steam] and bubbles in the coolant , worn piston/rings hard to start drop a little oil down the barrel if this helps it's worn top end. coil issues can cause problems as you describe. happy hunting.

[crispy]

Cheers, i'll pull the head saying I can get a gasket set easily and inspect everything. May aswell replace all the suspect items while the head is off. Even if it means pulling the engine out of the frame`

[nzspokes]

I would be pulling the carb down, checking the petcock, fresh plug etc before ripping the head off. Do a compression test if you think its more in the motor. But if it starts after you manually pour fuel in then it sounds more like carb or fuel delivery issue.

[crispy]

Sorry guys I left a couple of very important pieces of info out here. 1 - when I pulled the carb off it had hard starting, I checked out all passages etc and reassembled and had the same symptom as originally posted. 2 - after pouring fuel down the sparkplug hole it still doesn't want to start straight away, I have to give it full throttle and eventually it'll go. I'll try the oil down tere and kick it over and see if it is easier to start. As posted the compression is 150 PSI. checked cold. Just starting with choke only and no throttle it doesn't even give a hint of wanting to start and haven't crash started it yet to try. Also I always fit a fresh spark plug to see if this makes a difference

[nzspokes]

If you have poured fuel down the plug then you will need to have the throttle wide open. Have you checked the petcok valve?

[crispy]

Petcock valve aka float needle and seat?? or fuel tap on the tank?? Which does flow freely when turned on

[crispy]

Just thought i'd try the bike again today, put some oil down the barrel and tried it. kicking it over with quarter throttle and no choke it fired up on the fourth kick. I'm thinking there's a blockage still if it won't fire on choke with no throttle but when it runs, pull choke on and revs increase like they should expect with a choke on. So either it's extremely lean and there is a blockage somewhere. Would the engine being even slightly worn have the same effect??

[ktm84mxc]

Check the Reed valves on the intake side for chipping or cracks, these have also been known to loose tension over time causing a miss /hesitation . Did you remove the carb float bowl and check the flow into it when the gas is turned on ?

[crispy]

I haven't removed the float bowl to check the flow with the tap on, it's never been on my checklist until you brought up the suggestion t be honest

[crispy]

Removed the float bowl, turned fuel tap on and there's plenty of fuel coming out as you'd expect. I'm thinking of removing the carb yet again and removing all jets properly and blowing the carb out, again. When I first bought the bike it wouldn't stay going so I've improved it somewhat. Still had the long time kicking over to start it. Will see if there's any more crap in the carb. I've already cleaned the tank out. Might have to do this for a second time if I have anymore junk in the float bowl

[ktm84mxc]

If there's crap in the carb bowl it can only come from 2 areas the tank or intake/air box , fit an inline fuel filter and check all of the joints/seals on the air box and fit a new correct model air filter. You may need to remove the air box and pressure wash it.