Jump to content
Sign in to follow this  

Adjusting AP timing

Recommended Posts

I'm tuning the AC pump on my 07 WR250F using the ThumperFAQ article "Tuning the Accelerator Pump". I'm trying to adjust the timing. The first step in the manual is to put a 0.8mm (0.031in) diameter rod under the slide. My slide is open way more than that. The drill bit in the picture is 1/8". I assume the gap under the slide is normally less than 0.031". So, my question is do I turn the idle speed screw out to lower the slide until it touches a 0.031" rod?

http://i357.photobucket.com/albums/oo18/SteveR237/DSCN1489.jpg

Share this post


Link to post
Share on other sites

Back the idle screw out until it is no longer in play.

Share this post


Link to post
Share on other sites

But I will need to screw it back in to get it to idle properly. Won't that reduce the ap squirt? Turning in the idle screw will push the actuator rod down slightly which will reduce the volume of fuel in the AP reservoir.

I don't understand why I would set the timing with the slide at 0.031" when it needs to be open wider for proper idle speed. To eliminate the free play doesn't the timing screw need to be adjusted any time the idle screw is moved?

Share this post


Link to post
Share on other sites

Do not over analyze it.

Simply:

Back off on the idle speed adjusting screw. Count the turns. Continue untill the slide is completely down and the threaded part of the idle speed adjuster is no longer touching the threttle wheel. Make a note of the number of turns needed.

Set the AP using the .8mm drill rod.

Turn the idle speed adjusting knob back to where it was counting the turns to match the note you made earlier.

AP setup has nothing to do with idle speed. It is an adjustment made to be in relation to the throttle wheel position. The throttle wheel position used to initial setup is based on the slide being .8mm open in the carb bore.

This is also why if the slide is ever removed from the carb, it must be installed according to the proper procedure AND the AP timing checked/reset.

Share this post


Link to post
Share on other sites

If you pull up your subframe, you can watch the apump 'squirt' as you operate the throttle. You turn the screw clockwise to slow down the squirt (to just miss the slide as much as possible) or counter clock wise to speed it up. Using the 'gap' method is flying blind in my opinion. If you have access to the carb, why not prove the results.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×