How do you adjust dual throttle cables?

[estcstm3]

The PO who lives by me rebuilt and synched my carbs everything was running fine, idle and all. I then changed my bars rerouted all of my wires and I noticed that my right side throttle cable comes up after, or lags the left hand side.

What are the proper steps for me to get them to open the same.

1) Release the slack at the adjusters on the cable by the handlebar first? (would that be screwing them in or out, cant visualize)
2) Backing the idle screw down to the plate
3) Bringing the idle screw back to where it meets each throttle lever (dont know the actual names of alot of these parts)
4) Use the handlebars adjusters to get them in synch at this point (make sure left and right raise the at the same time when I twist the throttle) with the tank off I can see both standing over the bike.
5) See where bike is idling, turn screws on each side EQUALLY to move idle, if too hight or low?

I guess I am not clear on steps 3 and 4, not sure if I have it right.

 

[5twins]

On dual cable carbs, the cables are used to set the sync at speed (throttle opened). Sync at idle is done with the idle speed adjuster screws on each carb. You must set and sync the idle first because moving the idle adjuster screws adds or subtracts freeplay from the cables. That would throw off your "at speed" sync.

Once the idle is set and synced, you want equal amounts of freeplay in each cable so the butterfly plates start to open at the same time and will be open the same amount at any given throttle opening. Here's how I go about it ...... I set the freeplay I desire (about 1/8" to 3/16") in the left cable and lock it down. I then loosen the right one up more than that. Then I lift the sheath out of the cable holder down on the left carb just enough to take up its freeplay. While holding it there, I gently roll the throttle open a little bit, just enough to pull the sheath back down into the holder. This takes up all the freeplay in the left cable. While holding the throttle like that, I then adjust all the extra play out of the right cable.

 

[RatyXS]

^^ Nailed it..

Glad to see your ragggggggin month is over Mr Twins

 

[estcstm3]

Thanks 5twins. The bike was reving up when I turned it to the right, I traced it to the right side throttle cable. I then put about 5mm slack in that cable before it would lift the throttle at the carb. The issue now is that the left side raises instalty at the carb. I have turn the barrel adjuster for the left side throttle all the way in (which I believe is loosening it), but I cannot get any slack in the cable. I took the throttle calbe out form its routing and just have untethers up to the throttle...... Im stuck.

To get them to both rise at the same time the right side is too tight and then will rev when I turn to the right. When I fix that, the left side doesnt give me enough slack to get back in synch with the right side, it raises 1st every time.

Any thoughts?

 

[5twins]

It sounds like there's something wrong with your cables, possibly in the way they're connected to the twist grip. Split the twist grip housing open and have a look. Make sure the cable ends are hooked into the twist grip properly and that the cable elbows are correctly and fully seated in the housing.

 

[estcstm3]

Yup. Same page thats were I was going to next.

I will have to admit a really stupid action on my part. (Reiterating this is really my first bike project ever so theres defintely a learning curve).

When troubleshooting my electrical from an earlier issue and rewired my handlebars I took off my all my cables, I was hooking everything back up and didnt realize my left hand throttle by cable by the carb bent up and was touching the positive terminial on my battery.....and started cooking. Alittle smoke and a shinged end to the cable. I relubed the cable and nothing seemed wrong at the time. Just not sure if this is a conincidence or not.

Does Mikes XS sell throttle cables for the early year bikes? And now that I put lower bars on (super bars), I could probably go shorter atleats on my R side cable.

Thanks again.

 

[XSLeo]

At the throttle end one cable goes into the housing toward the throttle and one toward the center of the bike. This is where you determine the left and right cable. As you set on the bike you will see that the one toward the center is the left cable.
Run the cables as straight as you can. Run both to the right side of the steering neck. Then run the left cable under the frame just before the carbs to the left carb. The right to the right carb.
Watch where they run along the gauges and headlight. You don't want the gauges and headlight pulling the cables as you turn the bars.
This routing should be nowhere near your battery.
5twins gave a good description of the cable adjustment.
I used the procedure in the repair manual when I used dual cable carbs on my 75. Often referred to as the dead cylinder method. This works well if you are using the stock ignition. On most after market you need to use a different way to "kill" each cylinder. I made adapters that screw on the plugs that you can put the plug wires on. These adapters have a section of rod long enough so it isn't covered by the plug cap. To "kill" a cylinder I hook a jumper wire from this adapter to ground.
I start the procedure with the cables off the carbs. Using the dead cylinder method I get the carbs set for sync and idle speed.
Once this is done I hook the cables, with plenty of slack in the cables. I then adjust the right cables to about 1/8 inch free play. On the left I adjust it to match the right by lightly touching the cable and lever on the left carb with my finger tips while watching the right side. As I turn the throttle I can see the right side start to move, at the same time I can feel the left side. Adjust the left cable so it just starts to move at the same time as the right.
When doing carb part of the adjusting you need to run the engine, with the cable adjustment you don't run the engine or touch any carb adjustment, just the cables.
Once adjusted I then start the bike and turn the bars fully right and left. If the idle speed changes then you need to loosen the cables, loosen both the same amount at the adjusters.
While turning the bars left and right watch the cables as the flex near the gauges and such, they mat catch on something.
Leo

 

[estcstm3]

thanks! My throttle wires were run left on the left side and right on the right side. This was how it was wired even before I started my little project.

I had wires off just dangling (they were not connected anywhere) and it got moved and touched the positive terminal, nothing is close to my battery when routed.

 

[5twins]

When you change to lower handlebars, factory cable routing usually doesn't apply any more. You must re-route to make things work right. I do it all the time so I guess it comes easy to me now but from the terrible cable routing jobs I see on other people's bikes ALL the time, apparently it's a mystery to most, lol.

 

[estcstm3]

Yeah I have had to deviate with my routing for sure. Im thinking of getting an aux tank or fabing one out of gas platic bottle. I think that will help me out. Its a pain constantly hooking the tank up. WIth my track record I have to do something 5 times till I get it right....

 

[estcstm3]

5twins you nailed it. Took my throttle house apart, and the left hand cable had slipped out of the channel. Got it all back working now. Idle right at 1.1k and now reving with the bars to turned to eithier side. There is a smidge too much slack for my licking making the throttle alittle too unresponsive so I will use the barrel adjusters to work that out. Thanks again.

And a note on routing im actually routing both throttle wires around the steering neck and down the left hand side. The left hand cable stays left, and the right side cable cross over right infront of the petcock. This takes the visual slack out of the cable near my handlebars, limits sharp bends and just works.

Now (in a seperate thread) on to getting a good balance between finding neutral and having a clutch lever I can squeeze. Man when you change your bars you touch alot of parts of the bike, that take sensitive adjustment.