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Won't run under half throttle

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Working on a buddies 08 klx450. It ran fine 9 months ago. Sat in garage for months. I have cleaned the carb 4 times. Twice in chem dip. I have blasted air through all ports. Carb is like new. All ports are open, no blockage. It will only start with the choke on. It will not run without the choke unless throttle is half open or more.

I know you are thinking pilot jet is plugged but it is not. Problem is way worst than that. Hot start is not stuck open. I am completely stumped.

If you have had this problem before, suggestions welcome. Thanks in advance.

-gd

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Fuel mix screw not out far enough?  Chem dipping these carbs, you may as well throw them in the trash after.  There is a mid body o-ring between the 2 carb body halves that cannot be changed and does not like very harsh chemicals.  May not be carb.  Have you cracked up the idle screw to make it not die and back it off to see what happens?  Valves out of adjustment, grey stator connector may need to be blown out.  New plug if you have not done so.

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Fuel mix screw not out far enough?  Chem dipping these carbs, you may as well throw them in the trash after.  There is a mid body o-ring between the 2 carb body halves that cannot be changed and does not like very harsh chemicals.  May not be carb.  Have you cracked up the idle screw to make it not die and back it off to see what happens?  Valves out of adjustment, grey stator connector may need to be blown out.  New plug if you have not done so.

Seriously? There is an o-ring somewhere you can't get to?

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Working on a buddies 08 klx450. It ran fine 9 months ago. Sat in garage for months. I have cleaned the carb 4 times. Twice in chem dip. I have blasted air through all ports. Carb is like new. All ports are open, no blockage. It will only start with the choke on. It will not run without the choke unless throttle is half open or more.

I know you are thinking pilot jet is plugged but it is not. Problem is way worst than that. Hot start is not stuck open. I am completely stumped.

If you have had this problem before, suggestions welcome. Thanks in advance.

-gd

 

 

 

 

hi!!

 

have you checked valves????

 

have you cleaned the bike with water before starting the bike???  

 

 

any damage in the needle????

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Thanks for suggestions guys.  I may order the oring set, thanks.

 

My chem dip is not that strong.  I left a little oring from a previous carb over night by accident.  It was fine the next day.  But good suggestion anyway.

 

I can only suspect the pilot circuit is not working properly. I don't know if that means fuel is not moving or there is tons of air being sucked in.

 

I'm going back to see the local kawasaki mechanic today.  Hope he has answers.

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Moved from other post by dres0081

 

"Do the rpms seem to climb rapidly and come down slower than usual when blipping the throttle? Sounds kind of like an air leak between the carb and head spray carb cleaner around that area see if the rpms climb "

 

 

I'd say the RPMs come down real fast and the bike wants to die very quickly (no fuel).

-gd

Edited by Garage_Dog

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Fuel mixture screw has been adjusted between 1.5 - 3 out with no change.  Needle is fine.  I've gone through this carb 4+ times.

 

Gray stator connector??/...

 

It's not a valve issue.

 

Mechanic said sometimes (but not often) these carbs can get dirt stuck in the mid section of the carb.  Near impossible and very time consuming.  Better off buying a used carb on ebay.  He currently had a yz450f with the exact same issue.  He swapped out carbs and the bike was fine.  Put the old carb back on and same issue.  I asked to use a spare carb and he will have one for me to try next Wed.

 

I'll probably tackle that midsection in the meantime.

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The grey stator wire can get water in it and cause all sorts of headache.  Behind LH radiator, unplug, blow out with light air, add dielectric grease.  Cross fingers.  I beat my head against a wall for a while before figuring that one out.  Bike did the same thing.  Worth a shot.

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I checked the gray connection behind the left radiator.  Air blasted just in case but I didn't see any H2O or other residue.

 

I took my carb to another mechanic (Ryan at moto-one.net).  He said the accelerator pump passage was clogged.  He also noticed the starter jet circuit was gummed up too.  I hope that fixes the prob.  I'll update later this week.

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Yep, bike runs great other than the hanging idle.

Jets 45, 170

Needle 4th

Snorkel removed, smog capped.

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the hanging idle is common to these bikes, they are designed for trails and the have a circuit that tweets the timing in the lower gears to prevent stalling.  Disconnect the shift sensor to stop it.

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I read somewhere it retards the timing when in neutral by 7 degrees to help the e-starter work easier.

If you disconnect it, you are always retarded 7.  Can someone with  a timing light confirm this?

 

I still have my GPS and TPS hooked up and I dont get the hanging idle anymore once I got the jetting and mixture screw dialed in.

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I've read just about every thread on the hanging idle. ... I will just go at it and see what happens.

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Ah... In my haste, the main jet was only finger tight and vibrated loose. I fixed that (I can remove and replace the carb in my sleep) and installed a R &D flex fuel screw. The bike runs and idles perfectly. I did not have to cut any wires either.

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