Keihin PWK set up

[scubarusteve]

We did a large cleaning of my wifes CRF205X this winter, Everything went amazing but the bottom 1/4 of the throttle return doesn't have the same "snap" it used to, It returns but slowly, Had both cables complete off and carb removed and cleaned, Everything works amazing like it should. And no this is not a hanging idle, we can easily see the throttle tube turn slowly and unrestricted.

Thanks for any help!

[cerealkiller]

I would first rule out an issue with the cables, i.e. check that the cables aren't pinched or bent somewhere.Take off the gas tank, see if the throttle returns easier. Remove the cables from the carb, see if they pull/push through without resistance (in case the cables were bent and damaged while you were working on the bike).

Are you sure it is a Keihin PWK? I would have guessed that bike had an FCR.

PWK:



vs. FCR:


If it is indeed a PWK, you can screw off the top cap and pull the throttle to see the cable pull on the slide and compress the spring. I.e. on the picture below unscrew #15, and pull up - #'s 16, 19, 31, 14, 12, 13 and 11 will all pull out the top in one piece. Then as you twist the throttle, you can see the cable pull up on the slide and compress the spring.



If it is an FCR, there's a cover on the side held on by an hex-head bolt (or two - it's been awhile since I had one). Then you can remove the cables from the carb and twist the linkage with your fingers to make sure it has a strong return spring.

[axel99]

If the bike has hand guards check for clearance with the throttle tube

[scubarusteve]

My bad its an FCR, The throttle return is adjusted by the cable adjustment on the side of the carb? i will try that, thank you!
The throttle tube is free and clear no binding.

[cerealkiller]

The cable adjusters where they connect to the carburetor are just to adjust free play. That could be the issue only if the throttle return cable is so loose that it isn't pulling on the throttle for the last little bit of travel before the fully closed position.

If that isn't the issue, then you would need to remove both cables and twist the throttle shaft assembly (i.e. #12 below). The spring that wraps around it (#14) should be firmly pulling it back to the closed position.

If it doesn't want to twist back all the way to the closed position with gusto, the spring could be partially unwound or the slide (#19) or needle (#23) could be binding. At that point you would need to disassemble the carb to check what's catching.

[cedric]

Disconnect the cables and turn the carb crank by hand, this will tell you if the issue is in the carb or with the cables. Proceed from there.

[Stevemtb]

The vacuum plate on the slide is sealed correctly? #21 in cerealkiller’s diagram. I once got some carb cleaner on the oring behind the plate and it wrinkled it enough that the plate didn’t seal right. The extra thickness caused the slide to drag on the way down.