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Any Suggestions Apperciated

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I need some help. 2007 KX450F.

Out riding and after doing a high speed section when I came into the turn bike stalled fired right back up but when it gets to mid throttle it cuts out and missses and stalls when coming into a corner.

Cleaned carburator checked valve clearance new improvement.

Replaced spark plug and that eliminated the stalling in the corner but still have the mid throttle cutting out. (Bike runs perfectly everywhere else just at a constant throttle)

Cleaned carb again no improvement.

Replaced coil no improvement

Took kill switch completely off bike. No improvement

Unpluged all connectors and cleaned them with contact cleaner. No Improvement.

Cleaned carb again and replaced power valve no improvement

Moved the needle down one clip setting and that fixed 95% of the problem but of course the bike is running hot.

Read some of the older posts and had several suggestions about replaceing the jets so I ordered all new jets with the team green recomendations and a new top end.

Installed new piston and rechecked valves. Installed new jets in carb rechecked float height setting. And put needle back to third clip position.

Still have the same cutting out at a constant throttle.

I am usually the one that everyone calls to fix their bikes so this has been extremelly frustrating. I have spent hours on here reading pages over the last month trying to find the issue with this so if you guys have any suggesting I am willing to try it...:smashpc:

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Yeah, that is a weird one.

Thinking about constant half throttle ... What about a mechanical issue in the carb, caused by wear, affecting the alignment of the slide, or the alignment of the needle?

If you have a friend with an 06-08 CDI, then you could plug that in and give it a go. I know it's very unlikely to be the problem, but simple to try if you have the part.

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Someone over in Intake/Jetting said something about checking the needle jet so I will see what I find.

I replaced the AC Pump all the jets the throttle valve plate and the seal. Only two other moving parts in their that I didnt replace and they show no signs of wear.

I am trying to get ahold of another bike today to do some part swapping. Also checked the surface that the needle jet slides in and its ok.

Edited by Tapkawiman
Update

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i have heard of the emulsion tube wearing out and causing poor running as mentioned earlier...also the vent tube on the gas cap could be suspect....

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emulsion tube is in the carb...its what the needle rides in...

It's called a ' needle jet' and it's what the 'jet needle' rides in, and what the 'main jet' it attached to.

What throttle position consistently causes the problem?

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Today I swapped carbs with another bike and cdi boxes no change. TearPping back into the top end hoping that I find what ever I'm over looking. It cuts out from a quarter throttle and up.

I know thats a pretty broad area but anywhere in that range once you stop rolling the throttle on and hold it constant it starts cutting out or hesitating.

Pulled valve cover and checked valves again along with the valve springs(thought maybe one had broke but no such luck). All looked good.

Has anyone had a crank sensor go bad or cause a symptom like this?

How about a cam chain stretch?

I have went over the harness and also cleaned all the connectors?

:smashpc:

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Today I swapped carbs with another bike and cdi boxes no change. TearPping back into the top end hoping that I find what ever I'm over looking. It cuts out from a quarter throttle and up.

I know thats a pretty broad area but anywhere in that range once you stop rolling the throttle on and hold it constant it starts cutting out or hesitating.

Pulled valve cover and checked valves again along with the valve springs(thought maybe one had broke but no such luck). All looked good.

Has anyone had a crank sensor go bad or cause a symptom like this?

How about a cam chain stretch?

I have went over the harness and also cleaned all the connectors?

:smashpc:

You need to do a leak-down test.........

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Alright I am bald know.

Did a leak down test replaced two intake valves did not help the problem.

Talked to a tech at the ProChallenge in Texas and he said they have had wire harnesses do some weird things so got one of those. No luck still cutting out.

So i am know down to the stator. Have yet to find a post about one that was bad that caused any kind of problem even remotly close to what is happening on mine.

Hot Start. Dont know how it could cause this especially when I have no Idle or starting issues with the bike.

Crank sensor I would think that if it was a crank sensor I would have the issue at other times not just the the quarter on up throttle position.

And this is the kicker the bike runs fantastic except for that consant throttle area about three quarters. On my track when I ride it you cant tell there is anything wrong but when I go to a track that has long sweepers that require a constant thottle it does it.

Edited by Tapkawiman
Grammer

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Alright I am bald know.

Did a leak down test replaced two intake valves did not help the problem.

Talked to a tech at the ProChallenge in Texas and he said they have had wire harnesses do some weird things so got one of those. No luck still cutting out.

So i am know down to the stator. Have yet to find a post about one that was bad that caused any kind of problem even remotly close to what is happening on mine.

Hot Start. Dont know how it could cause this especially when I have no Idle or starting issues with the bike.

Crank sensor I would think that if it was a crank sensor I would have the issue at other times not just the the quarter on up throttle position.

And this is the kicker the bike runs fantastic except for that consant throttle area about three quarters. On my track when I ride it you cant tell there is anything wrong but when I go to a track that has long sweepers that require a constant thottle it does it.

Have you un-plugged your TPS to see if the problem changes/goes away? If it does, it needs re-calibrating. If it doesn't, or won't calibrate, it's your CDI, most likely.

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When we swapped carbs we swapped the whole carb with the TPS on it.

Have not checked the crank sensor, neither one of the local Kawasiadi dealers have a manual for that bike (Yea I know how do they not have one) have searched and posted on the int and havnt had any luck. And to top it off ordered a manual on line and its been 6 weeks and still no manual...

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knowing these bikes the stator should have been checked wayy before replacing intake valves, harness, etc etc. Its probably the stator. Krannie raises a good point that it could also be a cracked plug wire. Ive had that happen, but it was on a pitbike where the wire is more exposed and susceptible to damage. ALL my $ is on the stator. Would have been from the start.

Edit: well maybe not from the start, but once u checked the carb and CDI i think the next logical step is the stator, since its happened before on these bikes.

Edited by stlavsa

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Ok flywheel and crank sensor check out good.

Never Mind this below found out my meter cant do what I was doing with it got another and the coil tested out ok

..

Not gonna say it couldnt happen but in my past experinces this is usually faulty test equipment or faulty person doing the testing. l also pulled off the plug cap and tested straight into the coil wire and on the old one I puntured the wire right down next to the coil to try to get a reading. Have a hard time believeing its my tester when everything else tested out good except the coil. :bonk:

Edited by Tapkawiman

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