throttle stop screw help

I have a 98 yz 400 and I have no idea what to adjust the throttle stop screw to. (not the idle adjuster screw) The manual gives no specs. I took the carb apart to clean it and I don't know how mant turns to set the screw at. By the way what does it do anyway :thumbsup:



everyone is silent both in this forum and the jetting forum....maybe noone knows :thumbsup: Greyracer :thumbsup:

I just did a wr400 idle screw and the book says to record the factory # of turns before removing it and that's what I did. From my years of rebuilding all types of carbs, I will turn in the screw (while counting the turns) till it's LIGHTLY seated and write the #'s down. The wr was around 2 1/4 turns. most old carbs seem to be around 1 1/2 to 2 turns from lightly seated. You can try starting at 2 turns out, start the bike and turn in the screw till the idle starts falling off, then back out 1/2 a turn (I think that's the richer direction). Your complete fuel mixture starts with the idle, then adds in the needle mixture, then the main jet mixture. So you really want the idle to be good. And I hope you're talking about the idle mixture screw and idle rpm stop screw.

Does that screw have any adjustment? Isnt that where the slide attaches to the throttle shaft? I dont believe it has any adjustment, just snug/tight.

the weird thing is that as you can see in the pic, there is a screw in the center and there is a nut that slides over the screw. the nut locks the screw in place. The book says to record # fo turns cet by factory but this is an older bike

has anyone had this problem before while cleaning their carbs? will this screw affect the way the bike runs? any ideas would be helpful


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