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WR Sputtering

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Hi guys,

I've got a wr250 that is giving me absolute hell, its an 01 model so not really new. Anyways the bike starts fine, idles fine and revs out fine but as soon as you hold the revs in one spot (cruising speed) it splutters and dies for a second then catches again and repeats, it does it whenever you hold the throttle at constant revs even top end. The front and tail light have been taken off and replaced with yz plastics if that makes a difference, so far have rewound stators, replaced ht coils, done the carb about 10 times (done by top yamaha macs) disconnected the throttle position sensor and regulator rectifier even cut the lighting wires leading from the stators and no change, if anyone knows what it might be pllleeeease let me know cause i dont know what else to try

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Clogged fuel filter / petcock. 

 

Bad reeds.

 

Plugged fuel tank pressure release hose.

 

Main jet is too big causing to run rich, wetting the plug.  Try to put in a smaller main jet and see if that helps.

Edited by Honda_Power

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jeezus doode you might as well tell him his spritzer valve is bad.

 

Where is the needle positioned in the carb?

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jeezus doode you might as well tell him his spritzer valve is bad.

 

 

LMAO!

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Clogged fuel filter / petcock.

Bad reeds.

Plugged fuel tank pressure release hose.

Main jet is too big causing to run rich, wetting the plug. Try to put in a smaller main jet and see if that helps.

Please explain where the reeds are in a WR250F.

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Hahaha reeds! The reeds are bad....... This must be the case. My reeds in my 4stroke give me a super powerband but only when I run my 4stroke at 32:1 oil mix ratio.

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Sounds waaay rich.

Post your carb jetting here if you know it.

Pilot jet

Main jet

Needle model & clip position

Plenty of help here if you supply some info.

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Hi guys thanks for the replies, how does a 4 stroke have reeds? I've cleaned the tank even changed the smiley in the fuel tap too while I was at it, replaced the fuel line and fuel, I cant remember the jetting off hand but will check on monday, needle is in the middle at the moment but I've tried all positions and played with the mixture screw as much as I could but still no difference at all I know there was a problem with the regulator spiking the ecu during mid range if you take off the front light but everything is disconnected now, it revs like a bat out of hell but hold the throttle in one position for a second and its tickets until you downshift and get the revs up

Edited by genocidal_josh

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I've also checked and changed the float height (did it with a clear breather pipe held up against the side of the carb and followed specs from the manual) its not the right tool but works the same lol

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Hey Josh,
I believe I'm having the same type issue with one of mine, not same year as yours.

Starts, Idles ok, will accelerate, won't hold constant throttle position without totally cutting out.

I couldn't even time jumping a puddle or raising the front wheel with it.
I have some spare electrical parts that I'm gonna swap... so I'll let you know the outcome for me... might shed some light on your issue.

I've done same as you, cleaned carb, new sparkplug.  I suspect the coil/plug cap or ECU.

L8tr, Ron

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Hi Ron mine has been doing exactly the same, thanks for the update, if you do by any chance swap back the coil could you me know the outcome? Have replaced the coils already so im starting to think its the ecu.. which is never a good thing

Hi Ron mine has been doing exactly the same, thanks for the update, if you do by any chance swap back the coil could you me know the outcome? Have replaced the coils already so im starting to think its the ecu.. which is never a good thing

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I've seen those on ebay for cheap, didn't price from TT or bikebandit.

 

BE AWARE: the CDI/ECU for 01/02 is different from 03/06 versions and YZ may be different from WR, I haven't researched that.

I compared my CDIs, 03 to 05, and they had same part numbers on them.

 

The sparkplug cap on your bike is a conventional cap and can easily be replaced from another bike as a test.

I would suggest that first.

Yours has a separate coil from the cap like the YZ/WR400, and I would think those might be interchangable.

You can check bikebandit.com or some other site for part numbers.

 

Mine has coil on plug like a Corvette or some of the other newer autos.

I'll get back this afternoon on my plug cap.

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OK Josh, last update on this thread.  I'm gonna post a new thread.

 

For the record, I swapped back in the original plug cap (coil on plug) and it worked just as well, which confirmed that the problem is the CDI.

 

If it had not been for your post, I'm not sure I would have found my issue as soon, so thank you.

 

If you could find someone willing to swap with you for a trial run, that would be optimal. 

Otherwise, I'd recommend ebay since a new oem part is over $325 USD, not sure what it is there.

Good luck with it.

L8tr, Ron

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Hi Ron,

Thanks alot for your help had it not been for your help I would still be sucking my thumb haha, tried the plug cap now but no luck was hoping it wouldn't be the ecu but atleast I know what direction to go in.

Catch you on the forums, Josh

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