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The throttle valve (slide plate) stucked in the upper position

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Hi guys,

Today I installed a FMF muffler and a megabomb and when I was tuning the bike for this new set up, my frind´s son bliped the throttle when I was changing the needle position.

The throttle valve (slide plate) stucked in the upper position and I can´t release it. Is

there anything that I can try without disassemble the bike to take the carb out?

Thanks

Mauricio

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Did you line up the grooves on the slide with the pins in the carb?

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Did you try to remove the needle to see if that was the cause? If it is not the needle, there are two possibilities (both of which should really be done with the carb off).

1) Your throttle stop screw is missing or t0o short or the the slide is misadjusted where it attaches. To resolve, tighten/replace the stop and/or re-adjust the slide where it attacjes to the thottle shaft. You will need to then reset/check the AP timing.

2) You over centered the AP cam and it jammed. You must remove and reinstall the throttle wheel/slide to reset. Then reset/check the AP timing.

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Thanks for the answers.

I took the carb off and I found taht the spring that goes with the throttle cam was out of its position. I think that I´m using a too short throttle stop screw and with the top of the carb off, it let the cam to spin more than it should.

What is the correct size of the thottle stop screw?

Thanks

Mauricio

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Well, no idea what bike you have but if you have a Yam WR, get the throttle screw for the same size/year YZF. Too many cut the screw and cannot get it just right. A millimeter matters.

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William,

I have a 2009 wr250F. Do you have the correct yzf screw part number?

Thanks

Mauricio

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Thanks.

I have a friend in USA. I will buy this part there. Here in Brazil is very difficult to find small parts laike this one.

Thanks

Mauricio

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24.765 mm overall length is what you need to cut it to.

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You have no idea how many 'hacksawed' screws I have seen, cut crooked and rough, lengths varying wildly. So unless a person knows how to properly cut and finish it, I highley rec. just spending the money.

I figure if they know how to properly finish the screw, they also will not ask what to do....

Edited by William1

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Hacksaw??? I do mine on a lathe Sir.....:bonk:

PS...You are right though :smirk:

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Yup, hacksawed, held by vicegrips. :smirk: That is the most common way.

Some use a dremel with a cutoff wheel but still get it crooked. Few bother to grind the end slightly rounded and polish to a perfectly smooth surface.

You are one of the few that do it right. I am too lazy, I just buy the YZ one....

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just got done putting my carb back together. PO cut the throttle stop waaaay to short. ordered the YZ. very frustrating till i figured out was was going on. the cam behind the throttle wheel moves past the arm for the accel pump which catches and holds it open.

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A simple check is to look down the carb throat (engine off of course), Roll the throttle WFO. The bottom edge of the slide should be flush with the top of the bore of the carb.

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A simple check is to look down the carb throat (engine off of course), Roll the throttle WFO. The bottom edge of the slide should be flush with the top of the bore of the carb.

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A simple check is to look down the carb throat (engine off of course), Roll the throttle WFO. The bottom edge of the slide should be flush with the top of the bore of the carb.

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A simple check is to look down the carb throat (engine off of course), Roll the throttle WFO. The bottom edge of the slide should be flush with the top of the bore of the carb.

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yep. thats how i found it. my throttle stops turning just short of the point of no return so it doesn't happen while riding, but I ordered a yz screw anyway. even with it that far open and the slide about 1/8th out of the bore of the carb it still doesn't touch the stop.

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just got done putting my carb back together. PO cut the throttle stop waaaay to short. ordered the YZ. very frustrating till i figured out was was going on. the cam behind the throttle wheel moves past the arm for the accel pump which catches and holds it open.

This was exactly what happens to me....

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