Throttle linkage issue

On my 73 850 with a single 34 mm Mikuni, this is what I am experiencing: Just put everything back together after installing a Pazon Sure-Fire. The single Mikuni linkage just out of the carb is a tight fit and always leaves something to be desired. Now with all buttoned up, the motor idles fine until the handle bars are turned to the right and then the revs go from around 1000 RPM to around 3000 RPM. Straight and turned to the left, the idle is fine. It does increase revs if I push the linkage around but I can't even see cable movement when the handlebars are turned to the right but the revs go up every time. Before putting everything back together, I did have the slide out of the carb just to clean things up. When I first put the tank back on, I left the throttle linkage free and unobstructed so thinking that that might be my problem I secured the throttle linkage to the frame with ties but still had good action at the throttle and the rev problem still existed.

Do you have just the Mikuni spring? I had to put an Amal spring inside the Mikuni spring to assure that the slide would close. Hand effort on the throttle was not affected that much. I've found that leaving the throttle cable loose to find its own way will avoid the rpm increase when turning the bars problem.

My kit came with a throtle cable with angle at the carbend and the top nicely clears the frame tube. RockyPointCycles.

Sounds like you have a short cable or at least not enough slack out front.

Cable and carb spring was working fine up until now although I would like to get one of those angular fittings. My cable is plenty long and has a nice big loop in front of the tank. I tried it completely loose and also secured with ties to the main frame member. If I take hold of the cable where it loops in front of the tank and push and pull it lightly, it causes the revs to go up. Should that happen?

Another vote for the angled extension. I think they are 45 degrees.

Maybe you are adjusting the idle with the cable :?: The cable should be slightly loose with the throttle released and the idle should be adjusted with the idle screw.

Jean

Jeandr said:

Maybe you are adjusting the idle with the cable :?: The cable should be slightly loose with the throttle released and the idle should be adjusted with the idle screw.

Jean

Click to expand...

Thanks. I believe that is my problem. Not knowing any better, I was adjusting the idle with the cable. So if I understand correctly, I should set the cable fine adjust in about the middle of its range and then adjust the nut on the top of the carb so that the linkage is just slightly loose when the throttle is released and then set the idle with the idle with the idle screw on the carb? For sure, I will get the 45 degree fitting at the next opportunity.

Yellow_Cad said:

Jeandr said:

Maybe you are adjusting the idle with the cable :?: The cable should be slightly loose with the throttle released and the idle should be adjusted with the idle screw.

Jean

Click to expand...

Thanks. I believe that is my problem. Not knowing any better, I was adjusting the idle with the cable. So if I understand correctly, I should set the cable fine adjust in about the middle of its range and then adjust the nut on the top of the carb so that the linkage is just slightly loose when the throttle is released and then set the idle with the idle with the idle screw on the carb? For sure, I will get the 45 degree fitting at the next opportunity.

Click to expand...

With the throttle closed, there should be a little slop in the cable (about 1/8") so that when you open and let go of the throttle, the carb should close with a metalic sound. Adjust the idle with the idle screw, I think the Mikuni has a thumbscrew for that. Then you should be all set.

Jean

OK got the 45 degree fitting and now I seem to have other difficulties. The fitting I got from Rabers adds about 1 1/2 inches to the amount of cable that is now consumed in the fitting so does this mean I need another cable or what? With fine adjustment and 45 degree fitting made as short as possible and no twist grip attached, there is not enough cable to let the slide completely close. Is there a good way to cut the sheathing so that there is more cable length? I got plenty of overall cable just not enough exposed inner cable.

Hmm...I thought that all Commando's came with Amal carbs. No linkage issues as far as I know.

Sorry, couldn't resist.





They'll pry the Amals off my Commando when I'm dead...not before!

Good luck with the far east carb(s).

You can cut the cable sheathing if you're very careful. Most are made of tough, flat-wound wire covered in vinyl. The trick is to not cut th cable itself. First you have to get the ferrule off the end of the outer part. The best way to do the cut is with a sharp nipper or diagonal cutter. You have to gnaw around the outside in a sort of pinching bite while not taking enough of a bite that you get into the inner wire. Once you get a piece of the outer separated, you can strip off the vinyl cover and unwind the flat wire coil. After you get that off, you can slide the ferrule over the newly-cut end with a spot of super glue to keep it in place until the cable is snugged up in its fitting.

Danno said:

You can cut the cable sheathing if you're very careful. Most are made of tough, flat-wound wire covered in vinyl. The trick is to not cut th cable itself. First you have to get the ferrule off the end of the outer part. The best way to do the cut is with a sharp nipper or diagonal cutter. You have to gnaw around the outside in a sort of pinching bite while not taking enough of a bite that you get into the inner wire. Once you get a piece of the outer separated, you can strip off the vinyl cover and unwind the flat wire coil. After you get that off, you can slide the ferrule over the newly-cut end with a spot of super glue to keep it in place until the cable is snugged up in its fitting.

Click to expand...

Thanks for the post Danno. Makes good sense. I'll give it a whirl.