Throttle cable - won't close completely at carb

[ryamatt]

I put a new standard length Motion Pro throttle cable into a Lowbrow single pull chopper throttle body and my BS38's. I can't get it adjusted at all so that the throttle fully closes - as you can see in the picture it doesn't come close to hitting the idle adjuster. Also, the spring is doing nothing at the handlebar to snap the throttle closed.
Crappy throttle body? Crappy cable adjustment? Wrong cable length? Something at the carb end- spring?

 

[angus67]

is there anything like a adjuster at the top? by the throttle? Im guessing you have some sort of aftermarket "whiskey" throttle?

 

[ryamatt]

It's the common chopper type. Not totally el cheapo plastic, but but not a nice Biltwell Whiskey throttle either. It twists ok on the bars and the friction screw is a all the way out on the throttle body, so I don't think that is an issue.

 

[figure8]

I've had that issue before. Are you sure the throttle tube is snapping all the way back down? It can only be two things. The throttle tube isn't closing all the way or the cable isn't long enough.

 

[TwoManyXS1Bs]

There's a flange on the cable outer that normally fits all the way up, flat to the throttle body.
So, there's your missing cable slack. That adjuster on the throttle body is in the way.
You'll need to get creative here.

 

[fredintoon]

Hi ryamatt,
2-many's modified photo shows the problem.
Remove and discard the generic twistgrip's cable adjuster so the cable's raised ring can abut the adjuster's threaded hole.
Make a little locking plate to keep the cable's raised ring in place. The plate can be held by the twistgrip's friction adjuster screw's locking nut.

 

[figure8]

I stand corrected, good luck.

 

[ryamatt]

Thanks for this. I am going to play with it tonight and see if taking that off helps. I'll let you know.

 

[RFeng]

I had that problem with my '77 - I gained just enough length by hacking off the adjuster nut on the grip end of the cable. No issues for 2 thousand miles since...

 

[ryamatt]

Yup, taking out the nut solved the issue of the throttle not returning to the stop at the carb. However, I am still getting no snap back to closed at the grip. When I open it, it stays open unless I twist it forward.
Is this the spring at the carb? Just what you get for buying a 20 dollar chopper throttle?

 

[figure8]

Take the cable off and see how strong the snap back is on the spring. If that's fine, the throttle tube might be binding up in the housing or on the bars.

 

[TwoManyXS1Bs]

This sure brings back memories of a couple years ago. May have been member Pristic.

http://www.xs650.com/forum/member.php?u=10899

There was discussion, fabrication and solution to the cable/throttle/dragging issues, same as yours.
Just can't seem to find the thread...

 

[fredintoon]

Yup, taking out the nut solved the issue of the throttle not returning to the stop at the carb. However, I am still getting no snap back to closed at the grip. When I open it, it stays open unless I twist it forward.
Is this the spring at the carb? Just what you get for buying a 20 dollar chopper throttle?

Hi ryamatt,
seems like something's binding up somewhere.
I'd say take it all apart and check if the carbs snap back with no cable attached, if the cable runs free when it's on the bike and if the twistgrip turns easily with no cable attached to it.
Once you find out what's binding, that's what you fix.
On a historical note, back in the day, Britbike twistgrips were made like that on purpose.
Brits drive on the left and before there were flashing signals one gave hand signals.
Having the throttle snap shut when one let go the twistgrip to signal can be hazardous to your health so the twistgrip was set to stay where it was when let go of.
The snap-back twistgrip was only used on racebikes.