This throttle cable setup is being a pain in my ***. What gives?
I have the original cable stay...
I have the original carbuteror...
I have a solid throttle cable...
I rebuilt the carb using the usa made zenith kit.
Problem 1...the accelerator pump seems to be sticking. It doesnt want to allow the butterfly to return to idle. If I unhook the the pump arm, i don't have this problem. I even tried an nos harley pump cam. Same problem.
Problem 2...no matter how I adjust the cable, I have problems. Either the butterfly won't open past 3/4, or it won't return to idle position. Nothing in between.
I've tried adjusting the the cable with the throttle all the way open while holding the butterfly open.
I've tried it with the butterfly closed with the throttle completely closed. Same results.
Someone please help me, this is turning out to be the most problematic harley bike I've ever owned.
And before someone says it...I have the books. The service manual, and the parts manual.

This is as far as the throttle will close

Hard to see. But the throttle cable bracket doesnt keep the cable lined up very well, puts things in a bind

This is as far as the throttle will open

 

i have experienced this as well

first thing I found if you still have the original acc pump -
you Might see the holes in the totality of length from the umbrella to the pin is different - this needs to be addressed

I don't know if yours is going to be off but we found the pendulum in its operational circle was off causing it to stick - it was bending the stick when it was just at closed throttle

the entire mechanism - cable throttle blade and handlebar receiver will need to be slippery < cable lube is in the mix

 

I've had a lot of this issue. On the bikes that used external throttle (sportsters of that year for sure), they used a stiffer return spring. I would switch to that spring, then change out the piano wire for bicycle brake cable. I would check to make sure you have the throttle shaft seals on straight. Then see if the accelerator pump cam is binding, might need to be tweaked. I was ready to actually machine a piston to replace the cup, but got it working well with the tweaks I described.

 

When I got the bike, it had a cobbled up braided cable with an equally cobbled up return spring.
I already trashed the old accelerator pump, I should have checked the pin position before I did that. Hindsight, eh?
I think what i might do I build a new cable stay, to put the throttle cable more in line with the carburetor. If I could move the cable connector on the carb from the outside of the butterfly to the inside, that would be perfect. But I'd never get that rolled edge right.
I like the piano wire, myself, because of the cruise control ability, and it's what I learned to ride with. Other option is a super b haha
But I'd rather get this zenith working, because at this point, it's mocking me hah

 

Only thing wrong with stiffer springs etc... is that you will accelerate the wear on the already wear prone area of the butterfly shaft thru the Carb Body... We use the Lightest spring we can get away with... yet still get positive return... tho on mine I do have to manually return the Throttle [roll off] but, having learned on internal throttles... that is OK for me.

Reminds me.... If it has been rebuilt, it is not uncommon to have an Ill fit of the shaft in new Bushings... equals very stiff operation due to poor workmanship..

 

When the accelerator pump is disconnected, it is as smooth and slick an operating carburetor you could ask for. Even when the accelerator pump is connected, it will almost return to close, i think that's in the way the cam is shaped, though. It's when the cable is installed I'm running in to problems.

 

the cable is loading the side of the carb its on and that is sticking the works - run a braded cable we do it all the time but use graphite on the cable so its slippery smooth when done - its an old trick to use a Bendix in place of an alloy Tillson or even a linkert and the linkert the trick was to attach a return spring to the back side of the plunger when using a solid lawn mower cable

 

So youre saying the braided cable and return spring in place of the piano wire works well? It seemed really cobbled together. Maybe it was just this particular bike. The return spring was mounted through a couple small holes in the back of the air cleaner. I guess i could come up with something that looks better, that might be easier and work better than trying to build a throttle bracket/stop for the piano wire

 

the receiver for the throttle now on the bike is the left timer side as its a pull out when turning - the original was a push to go and its a common replacement for internal cables - when turning around the piano wire it lends its self to be a PINA at times

fix it how you see fit until all is lost then come back to this post and see what works

 

The Bendix throttle bracket alignment can be a pain. As John said, make sure the cable, spiral, plunger are well lubricated. I use bicycle brake cables for throttle cables. Readily available and much cheaper.