Sticking Throttle Linkage [Update: FIXED]

Hello everyone, I just got my carbs back together after replacing the throttle shaft seals. The rack is nice and square and the shafts and seals have been lightly lubricated with silicone grease.

I'm running into issues bench syncing. Testing the linkage action, I open the butterflies by pushing up on the 3-2 linkage. Both banks open just as they should, but when I release the linkage it does not snap closed. It comes to more or less half way closed (not where they started...they started shut). The butterflies will close if I push down on the linkage.

Are the linkage springs too loose? What else could cause this?

 

Re: Sticking Throttle Linkage

There should be a fair amount of tension on the throttle return springs. Not easy to hold the throttle open with your finger for any length of time.

Also check that you have the butterflies installed, and aligned correctly. Any misalignment will cause the butterflies to drag on the carb body.

Ghost

 

Re: Sticking Throttle Linkage

Or you didn't get the rack as "nice and square" as you thought.

 

Re: Sticking Throttle Linkage

When I replaced my seals I noticed the same tightness even though everything was squared up.

I just kept working the throttle... open - closed - open - closed to sort of break it in. After about 30 minutes or so of this it just started snapping shut the way it should.

Can't explain it other than to say the seals and shafts just needed to break themselves in.

 

Re: Sticking Throttle Linkage

I re-assembled the rack using two levels. When placed on a flat, even surface, there were no gaps. I don't think at all that it's not squared.

Here is a video of the butterflies sticking:

http://www.youtube.com/watch?v=-3WFZoCCYaM


I could not find many specifics regarding the tightness of the springs, or the nuts that go on shafts #3 (between 3 and 2), and #2 (between 2 and 1). I am thinking my springs are not tight enough, or these nuts are too tight, or both.

How tight are these nuts supposed to be:

 

Re: Sticking Throttle Linkage

Alright, a little update...

I broke the rack again to watch each individual carb's throttle action.

Turns out that the issue was with #2 and #1. The springs on these two were stuck between the linkage arm and the carb body, and were pretty tough to get wound up to proper tension without them getting stuck in there again...but I got them.

Now a new issue: In doing this I broke the outside throttle shaft SHIM on carb #1. :cry:

I am sick of waiting for parts! Haha... They don't seem very "proprietary" in design. Is there something I could use in the interim while I wait for a replacement? I haven't ridden in 2 weeks! LOL

 

Re: Sticking Throttle Linkage

Plactic(nylon) shim washers are at most good hardware stores(Ace, True Value, etc). I have several of them in my carbs,sand or file to the correct size.

 

Re: Sticking Throttle Linkage

Just picked some up. Thanks for the tip mlew!

Lesson learned. Test the throttle action on each carb before reassembling the rack!