Throttle cable to short?

I took the throttle & cable off my parts bike (82 XJ750rh) and put them on my bike (81 XJ750rh). The bike starts well, but pretty quickly races to high RPM. If I disconnect the throttle cable and work the throttle manually, things seem OK. Same if the throttle tube is off the bars and I use the cable. But as soon as I tighten it on the bars, I run into the same problem.

Is it possible this throttle cable is shorter? Is there some adjustment (besides the obvious barrel adjuster) that can be used to compensate for cable length?

 

Same handle bars and angle?

 

No, not at all, but there's ample slack. I can literally loosen the screws holding it to the bar and it works OK.

 

check your cable routing first lube cable and graphite on the grip assembly clean inside the tube and outside of handle bar

HCP2696 OEM original THROTTLE CABLE, with black curved plastic tube, adjuster nut, and thumb-wheel on the throttle end of the cable, for all 1981-83 XJ750 Seca and XJ750 Euro models. Wire length = 41".

HCP2655 Aftermarket THROTTLE CABLE, with bright plated curved metal tube, adjuster nut, and thumb-wheel on the throttle end of the cable, for all 1981-83 XJ750 Seca and XJ750 Euro models. Wire length = 40-1/2".


82 RH and 81 RH ?

 

sound like you need to lube the throttle tube and the slot for the cable hook-up inside the control where the throttle tube rests. Lube the cable while you're at it

 

or your parts bike had the wrong cable on it to start with.

 

Then it should not have worked on the parts bike either

 

Well, I don't have any assurance the parts bike ran. That's why it is a parts bike. Had zero compression in one cylinder (though turned over nicely) and tar in the carbs.

I don't think it's just a matter of lube or pinching because it opens and closes very easily. I can't even rev the bike up and down properly when the cabe is removed from the throttle tube and I work it by hand. It just starts to race as it warms up.

I'm starting to think its not the cable at all, but some setting or flaw in the carbs, and maybe I just had the idle screw turned in really far. I haven't really been able to reliably perform tests because I can't start it enough times in one session to eliminate all variables.

 

So, let's go all the way back to square one.

Why did you decide to swap cables?

 

Because the plastic elbow on the original broke. And the barcon switches were sun faded. The parts bike was stored inside and so has much nicer looking controls, made sense to just swap the whole thing over. Did the same on both sides.

 

Are you saying that you swapped throttle AND enrichment (choke) cables?
Can you post pictures of how they are routed?

 

Many times people hook them up reversed.......