Worn Throttle Body Shafts

[Karl Johnson <karljohnson@xxxxxxxxxxxxx>]

Since we're talking about worn parts on the throttle bodies, I thought 
this page would help clarify what normally happens...
http://www.largiader.com/tech/tb/

Check out the pictures at the bottom of the page. The throttle body and 
bushings are usually okay, it's the shaft which gets worn down. You can 
check for an air leak by using this proceedure from the late Rob 
Lentini...

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Problems with throttle body synchronization and accomplishment of 
"zero=zero" may, but rarely, be caused by  wear or failure of the 
throttle butterfly shaft bushings and/or seals.  While these parts are 
not currently available for replacement (though may be shortly), here's 
how to tell if you have this rare wear problem:

Spray carb cleaner, propane, or simply WD-40 at the throttle shaft 
pivot area with the engine running and listen for RPM speed-up.  These 
bushings/seals are located just outside of the cable wheels on each 
throttle bodythe arcing grooved wheel that encloses the throttle cable 
for each cylinder throttle body.  The area to be sprayed is between the 
surface of the cable wheel  and the throttle body casting.  When 
spraying, avoid the intake of the air box "horn" on the left side of 
the engine or you may get false RPM increases from inhalation of the 
solvent into the air box.

A speed-up indicates the solvent is being "vacuumed" past a bad bushing 
and/or seal and is being pulled into the cylinder as more "fuel."  Try 
this procedure at idle and at, say, 3000 RPM to pick up rotational 
differences of the throttle shafts. If you detect RPM increase you have 
little recourse other than a warranty claim or throttle body 
replacement at your expense. Subsequent parts availability may soften 
this expense in the future.
- -----------

I have heard some people test for a leak by sealing the area up with 
some grease. It works well enough some people just leave the grease and 
don't replace anything.

If there is a leak and you don't want to replace the throttle bodies, 
the web page has information about buying new shafts ($46).

Take care all.

Karl

On Feb 7, 2005, at 5:29 AM, Tom Brown wrote:

> John:
>
> After reading the rest of your diatribe....Don't feel bad I've wasted 
> whole
> days writing to this silly mail list too.   It's obvious to me that 
> your bike
> is behaving badly.   I think you're on the right track with replacing 
> the TB
> bearings and axles.   It won't run right until those are right.    
> From the
> sound of your post, I'd guess you've also been fooling with the TPS 
> setting to
> try and fix some of these issues.   You do have to get back to where 
> you once
> belonged, jo-jo.
>
> 0=0 is a good way to set the TPS.  Be sure and read the procedure 
> carefully
> and sleep on it a night before you dive in.    If you do this right 
> and your
> TBs are in good nick, I think your bike should run like new, or maybe 
> a little
> better.   It's not my experience that these engines get worse with age 
> unless
> something like the TBs go bad.
>
> I sort of agree that Bing may not have been the best choice for this TB
> assembly.   There is a known issue with these butterfly axels and 
> bearings.  I
> didn't know you could replace them without replacing the whole TB.   I 
> know
> several people who've just changed out the whole TB.   This obviously 
> more
> expensive, but it always works.   You get your new bike back again.
>
> Anyway, good luck with this.   Your bike should start.   Your bike 
> should
> idle.   You should be able to get it back to a point that you love 
> riding it
> again.    This is doable without reinventing the entire injection and 
> ignition
> system.   I'm gonna say again that if this is your street bike that 
> you depend
> on and expect to have on the road in a predictable time period and not 
> a
> science project, you should stay with stock components.
>
> You sound like a person who does what he wants.
>
> Have fun...remember, that's what these things were made for.
>
> -TB

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