WR250F Missing a little :/

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May 17, 2001
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#1
Whooo.... I have had some problems with my bike :) Some from bad luck, some 'cuz i am not too bright some times :) A few months ago when I got my bike, I could not start it for ANYthing... I would kick and kick and kick and kick... and it wouldn't start.. I bump started it a few times, and after I ran it some... it finally started getting easier to start. now I use the EXACT same method I did when the bike was new... and it starts 1st or 2nd kick everytime :) I guess it needed breaking in.

Now comes the not too bright part. I read all these posts here, and decided that changing my timing to the YZ timing would be easy enough for a guy like me with very little mechanical experience... I was wrong. Somewhere in the process, I screwed it up... fortunately for me my buddy knows more about engines than me, and he was able to come over and help me revert it back to stock timing :)

then I started her up and went for a ride... and I stupidly forgot to turn the choke off when I went riding... DOH!!!... and after a while it started missing, and finaly died (After I had apparently fouled the plug). I replaced the plug, and now it runs pretty good I think...

I have heard others talk about a "dead spot"... I do have this dead spot on my bike, and also, it doesnt seem to run perfectly smooth all the time... I don't know if this is normal or not.

Current config:
2000 WR250F
-exhaust tip removed
-removed plastic airflow thingie from the air filter area.

I am curious If I (and my more knowledgeable bike mechanic buddy) need to do anything to my carb settings? what about doing the grey wire removal thing? And what about the throttle stop? Any suggestions on all this?

If I replace the throttle stop with the one from the YZ would that work? If so... has anyone bought one ever? any idea how much that'd cost, or should I try and cut my existing stop?

Thanks for the info... love this message board. :)
 

MWEISSEN

Whaasssup?
Mi. Trail Riders
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#2
With what you've done to your bike, you definately need to visit your carburetor settings, and probably need to change the fuel screw setting, pilot jet or main jet. Call your motor buddy over and buy him a beer (or pop, not sure of your age;) ). It's missing because it is probably running too lean
 
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Jonny426

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Apr 30, 2001
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#3
wr power

WR250_Rider, You need the throttle stop to prevent the TPS (throttle position sensor) from going over-range. the spec I've seen is 9-11 mm.,depending on who shortens it. I cut mine way too short, so I went for the YZ screw(p/n 5JG-14591-00) for my 426. I believe the screws are the same 250/426. Also the "grey wire" modifies your timing curve at part throttle, so look for this mod here or at thumpertalk. You can find the wire in your shop manual pg.6-1. the lower box, outlined in dashes, shows a black/white wire with an "x" next to it.Just below you see a bl./w and grey wire together in the same connector.The non-U.S. bikes terminate the grey there,the U.S. bikes keep the circuit intact to your C.D.I. box. Open that wire and enjoy! Jonny426
 
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Dec 18, 2000
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#4
Go SLOW!

Do NOT make multiple jetting changes at one time. First try opening the fuel screw 1/4 turn at a time. First screw it in and count how many turns out it is. Then return to the starting point and turn it out. Write down every change you make. If you get out to 2.75 turns, you may want to go up one on the pilot jet. When you do, return the fuel screw to 1.25 turns out. Once it starts easy and does not pop on decelleration, then and only then, move to the main jet. For throttel transition changes 1/8 to 1/2, try moving the clip on the neddle dwon on clip at a time. Don't forget to keep records of changes and again, only one change at a time.

Do not remove the throttle stop, for reasons already mentioned. Go to ThumperTalk.com and get the proper length to trim it to or buy the YZ stop. If you haven' trimmed the stop, your only riding the bike at appx. 5/8 throttle.

If your buddy got your valve timing corrected, he may ne able to get you back to YZ. Give it a shot.

vetwfo'er
 
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#5
Good info...

Thanks for all the VERY good advice... I still have a few more questions though... someone (I cant remember who) told me that if it was running too lean that I could damage my engine after time... any truth to this? How can I accurately judge if I am too lean or rich? Is there a way I can look at the plug and tell for sure?

I am getting the YZ throttle stop, because I don't want to screw my origional one up.

I will follow your advice vetwfo'er and make only one change at a time, and keep records.. Currently the bike starts VERY EASY... I can now seem to start it (If I ride it every day) on first kick without a choke... although it starts a bit easier with the cold choke. However it DOES pop on deceleration once it gets hot... Is this not normal? If not... what does that tell me? too rich or lean? Also... what is the definition of "RICH" and "LEAN" ? I assume one is too much gas, and the other is too much air... wich is wich?

Thanks again for the info.

Randy
 
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May 17, 2001
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#6
Big Gun Pipe

Also... A guy I met the other day mentioned that I REALLY needed to get a Big Gun Pipe.... I am currently using the stock pipe, with the exhaust baffle taken out... so it is loud, but where I ride that isnt a problem... but I would prefer it to be quieter... but it seems to run better without it... what will the big gun pipe do for me? Anyone?
 

penguin

N. Texas SP
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Feb 19, 2000
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#7
The Big gun will Cost you a bunch of money. Get your other issues sorted out before you start making modifications. Like the others have said, change one thing at a time and test the change before proceeding. you start changing a bunch of things and you never will figure out what works and what doesn't, and could screw something up in the process, listen to th voice of experience:eek:
 

MWEISSEN

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Mi. Trail Riders
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#8
The popping on deceleration indicates a too-lean mixture. Try adjusting the low speed fuel screw out about 1/2 turn at a time, but first check how many turns out you are by turning it all the way in, stopping CAREFULLY when it seats (don't reef it down) and counting the number of turns it takes to reach that point. It should be about 1-3/4 turns. If you have to go beyond 2-3/4 turns or so to get rid of the popping, you should consider going up one size on the pilot jet.

As someone says, you should wait on getting a different pipe. To make your bike quieter and get almost the same performance as a new high $$$ pipe, get a White Brothers Vortip insert for your stock pipe. It's a lot quieter and still makes pretty good power.