Throttles up when I turn bars

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Jul 8, 2011
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I didn't see any discussion history on this one. A Brit Bike Buddy told me to secure the cable splitter secure to frame & leave the single cable from the twist grip to float. I've been putting up with this issue since 1974 when I bought my '73 Interstate.

Thanks for any solution or suggestion,
Dave
 
I leave my entire throttle cable assembly floating on my bike and route it in such a way that it is relatively secure but does not bind on anything. Securing the throttle cable assembly firmly to anything should be avoided.
 
Norton 's John Hudson recommended to tie the junction boxes to the frame. BSA even listed a junction box clip for the A65's.
Set up your throttle cable to minimum free play with handlebars turned to the right.
 
If the cable, or cables are not too short going to the throttle, tying the splitter to the frame might work. I never did it that way myself with Amals. I used two loose hoops of ziptie to hold the cable in front of and cables behind the splitter to keep the splitter close to the top tube and off the head. Cables could move fore and aft if needed with that arrangement. That said my bike is a long way from concourse.
 
Caution sacrilege coming: If you really want to fix it, throw away the entire choke, throttle cables, junction boxes, and throttle. Get a twin pull throttle and two Triumph 605/750 throttle cables and matching carb tops. Besides eliminating the junction headaches. syncing the carbs is easier with the inline adjusters.

With the junction box:
1) A little longer short cables helps - removes a source of binding.
2) After getting your idle right, make sure there in only a little slack in the tops of the carbs. Too much can cause the cables to hang up in the junction box.
 
The cables that go between the carbs and the choke and throttle spliter(s) look the same, but the throttle cables to the junction have slightly longer inner (operational) cable. You can easily get them mixed up, but you won't be able to bottom the slides, and they will raise your idle.

Best.
 
The cables that go between the carbs and the choke and throttle spliter(s) look the same, but the throttle cables to the junction have slightly longer inner (operational) cable.

The choke lower inners are longer.
 
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I had this issue, rpm changing with handlebar position a few yrs ago. Seem to recall is was solved by re-routing the single cable from the twist grip where it went around head tube. Think I had it round front to left side then along spine but it needed to be to right of head tube, if I recall correctly.

Also I found the cables entering the carb tops not squarely engaging with the adjuster furrels b/c they were bending too sharply along the spine. So a little re-working I was able to get them much more square to the tops. Never had the issue again.
 
I had similar problems with the splitter box setup & mutliple cables, the best thing I done was to ditch the entire stock setup (choke & throttle)
I have now installed Don Pender's carb gantry - one throttle cable instead of the many.
 
I had similar problems with the splitter box setup & mutliple cables, the best thing I done was to ditch the entire stock setup (choke & throttle)
I have now installed Don Pender's carb gantry - one throttle cable instead of the many.
That arrangment is so much better, I've checked the synch a few times since I fitted the gantry some years ago and it's not changed, but why would it?
 
The choke lower inners are longer.

I am loath to disagree with you and do appreciate the encyclopedic knowledge you have amassed and share with forum members.

But.

My customer had a set of both lower choke and throttle cables, he installed a set that did not allow the slides to bottom with the carb top adjusters fully collapsed and the twist grip end of the cable not connected.

I put installed the other (Barnett) cables and got perfect results. What I got from this is that the choke cables have a shorter inner, as DynoDave mentioned earlier. I convinced him to not us the choke.

If the choke cable inners were longer they may have fit well, but then the throttle cables wouldn't have worked in the choke position??

Best
 
My customer had a set of both lower choke and throttle cables, he installed a set that did not allow the slides to bottom with the carb top adjusters fully collapsed and the twist grip end of the cable not connected.

I put installed the other (Barnett) cables and got perfect results.

Choke cable inners are definitely longer as hopefully can be seen in the pictures below that the choke slide extends further than the underside of the throttle slide.
Throttles up when I turn bars

Throttles up when I turn bars



What I got from this is that the choke cables have a shorter inner, as DynoDave mentioned earlier.

He said the choke cable inner is the longer of the two (twice):

3-5/8 MK1 throttle and 3-7/8 choke.
MK1 concentric bare cables-lowers
throttle
exposed cable 3-5/8"

choke
exposed cable 3-7/8"
 
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I didn't see any discussion history on this one. A Brit Bike Buddy told me to secure the cable splitter secure to frame & leave the single cable from the twist grip to float. I've been putting up with this issue since 1974 when I bought my '73 Interstate.

Dave

This isn't an issue if you fit a twist grip with a 90 degree cable exit and route the cable on the far side of the headstock (i.e., on the same side as the twist grip).

- Knut
 
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Norton 's John Hudson recommended to tie the junction boxes to the frame. BSA even listed a junction box clip for the A65's.
Set up your throttle cable to minimum free play with handlebars turned to the right.
If the splitter is fixed to the frame there is no need for the lower cable outer sheath nor the cable length adjusters on the top of the carbs.
 
If the splitter is fixed to the frame there is no need for the lower cable outer sheath nor the cable length adjusters on the top of the carbs.
It's only cable tied to the frame !
 
I am loath to disagree with you and do appreciate the encyclopedic knowledge you have amassed and share with forum members.

But.

My customer had a set of both lower choke and throttle cables, he installed a set that did not allow the slides to bottom with the carb top adjusters fully collapsed and the twist grip end of the cable not connected.

I put installed the other (Barnett) cables and got perfect results. What I got from this is that the choke cables have a shorter inner, as DynoDave mentioned earlier. I convinced him to not us the choke.

If the choke cable inners were longer they may have fit well, but then the throttle cables wouldn't have worked in the choke position??

Best
There are many cable suppliers out there and some are better than others. Lengths and dimensions can be all over the place! You shouldn’t try and draw conclusions from one set, especially of unkown origin, IMHO.
 
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