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CaptainKnobby

accelerator pump timing screw

9 posts in this topic

Has any one tried just turning the timing screw 1 full turn clockwise from stock setting? I did today and it seemed to really improve the throttle response on my 05 yz450f.:applause:

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i have a 2005 yz450f and i put a boysen quickshot on it and didnt know a lot of diff mabe thats what i need to do, is adj my screw.

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well if you turn it in clockwise 1 turn like i did is that the right direction for quicker throttle response von beard? And the reason I did not do the wiring mod on it today was the bike shop did'nt have the size #65 or 70 leak jet on hand so I decided to wait until I got the leak jets to do it. Remeber me I pm,ed you last night about the mod!!!! and 1 other thing beard..... I was wandering? at wide open throttle on my 06 yz450f am i suppose to have a gap after I turn the timing screw to where it is just barely hanging on?

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well if you turn it in clockwise 1 turn like i did is that the right direction for quicker throttle response von beard? And the reason I did not do the wiring mod on it today was the bike shop did'nt have the size #65 or 70 leak jet on hand so I decided to wait until I got the leak jets to do it. Remeber me I pm,ed you last night about the mod!!!! and 1 other thing beard..... I was wandering? at wide open throttle on my 06 yz450f am i suppose to have a gap after I turn the timing screw to where it is just barely hanging on?

You need to set the initial AP timing to just miss the slide. Counterclockwise on the screw is earlier, clockwise is later.

As far as the gap goes, you don't want any gap between the black link lever and the screw at WOT AFTER the timing is set. If there is a gap, you need to shorten your rivet if you are going to wire it up.

Do you have an 05 or 06? The first post says 05 but your last post says 06.

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Baron, How do you set the AP Timing? While the bikes running or while it is off? Can you give me the steps to do this?

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Hey beard! its a 06 yz450f!.... so you are saying if I just turn my ap timing screw counterclockwise 1 full turn from stock it will give me a quicker throttle response?

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Setting the AP timing in a nutshell:

1. Remove carb from bike, but leave throttle attached and fuel in the bowl.

2. Turn AP timing screw all the way in until lightly seated and record numer of turns (be exact)

3. Turn screw all the way out

4. Give the throttle a quick twist and see if the bottom right hand corner of the slide has any wet spots. If it does, dry it off, turn the screw in (clockwise) 1/8 turn and try again. Continue until the slide no longer has any wet marks. Do not go more than 1/8 turn at a time, it's very sensitive.

This will get you the earliest squirt possible without wasting fuel by getting it on the slide.

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I have a 99' YZ400. I installed the Boyseen Quickshot and the directions called for turning the timing screw out (counter) but I could not find the timing screw? Any ideas? Is there even one on the 99' 400?

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