throttle advancing when turning handle bars ?

[Guest]

Hi, Just picked up a nice little 1981 GS650 GL. Run great, and needed very little to make ready (clean front brake light switch contacts). A problem that it is having is this... when I turn the handle bars, it advances the throttle. I'm not touching the throttle and it still does this. Seems to be more when I turn it to the right. Center is good, left advances it a little. I've had a few bikes, but never seen this. It seems like the grip is just a tad loose, and maybe because of this after market looking 'cruise control'. I'll try to post a couple pictures (when I can figure out how) of the top and bottom of the grip.

I was a little surprised to see only one cable... I thought they had to have the push/pull cables by 1981.

[azr]

Should be a simple fix. It might not be adjusted properly, try loosening the adjustment at the handle bar and see if that helps. It could be catching on the headlight or something up front. It could be that the throttle cable is not routed correctly. You'll have to take off the gas tank so you can see the cable fully. Turn the handle bar and make sure the cable is not pulling. Also make sure that fancy grip is not pushed on too tight and not allowing the throttle to 'snap' back.Your bike came with just the single throttle cable. The older models had the push pull.

[vttrailboss]

at this point the 'cruise control' is loose. If I push the throttle closed it seems to go to far, but it does stop. What is the correct routing for the cable? (I'm flying blind until I can find a manual).

Thanks for any help. It rides fine, but it pretty annoying at slower speeds or stopping.

[JEEPRUSTY]

http://members.dslextreme.com/users/bikecliff/

[William Groebe]

The throttle wire is too taut and when you pull to the right or the left the wire is pulled which opens the throttle. You can loosen the wire at the handlebars, or at the carburetors. I recommend at least looking to where the wire connects to the carburetors and checking out the routing of the wire. On my bike the wire itself was poorly routed, so it had a lot of slack by the carbs which made it taut by the handlebars. I just had to even out the slack and mine worked fine. Or adjust the nuts where the cable connects to the carbs if the routing looks fine.

Check out this video which shows the cable to carbs connection. https://www.youtube.com/watch?v=1z6G4G5_ko8

[chuck hahn]

That, and /or the cable itself is routed improperly and when you turn the bars it pulls on the cable.

[gsrick]

That, and /or the cable itself is routed improperly and when you turn the bars it pulls on the cable.

+1 that's usually the problem, unless the bars were changed to a larger style and not having enough slack in the cable for bind free movement.

[vttrailboss]

Hmmm.. I removed the cruise control thing, and noticed something. When I release the throttle it returns as I'm use to... But, If I roll it forward it moves a little more. Almost like something is slipping. The control is tight, and it looks like someone replaced the grips at some point. I've never had to replace grips... how do they come off? I'm waiting for that manual to down load (awesome!).

Later, I'll roll the throttle full forward (adjust the idle... runs to slow when 'bottomed out') and see if that fixes the slack issue.

Thanks for the youtube link. Dawino's greeting is always a surprise!

[tkent02]

How much free play do you have in the throttle? Sounds like not enough, and it sounds like the idle speed screw isn't tight enough.

[Albuq. Henry]

I am new to the GS. I also noticed the throttle rolls free forward and pulls the cable when rolled back.... some kind of one way clutch in there??

[tkent02]

Nope .

[Albuq. Henry]

HMMM..... guess I will be taking mine apart and see whats up... It was kinda weird, yesterday, when while cruisin I rolled off throttle past the stop and it rotated farther back than zero throttel then so "zero"moved farther forward than before so when I went back cruise position it was now pass postion... lol

[vttrailboss]

It appears to be something in the throttle. Almost like a detent that holds the throttle a click above closed... im guessing something to do with the non-OEM grips, and the aftermarket cruise control thing. Maybe the throttle is aftermarket?

With the idle knob adjusted it idles great, but you need to be conscience to roll it past where it returns under spring pressure... not a big deal, but annoying.

[chuck hahn]

Take a look at the channel the part of the grip sets in that hooks to the cable..see if its scrunched up anywhere. Look for drag marks from the barrel end of the cable in there. If the cable end is making marks, file it down. Have the cables hooked up to the grip and turn it around and see whats going on in the housing. Something is catching in there along the path of travel it sounds like to me. AND look at the cables where they meet the sheathes..good place for wear and hanging up cables.

[bwringer]

Also check the choke cable -- if it's hanging up or badly routed, it can also make the engine rev.

Cable routing is hard to give definite advice on, because almost every GS has had the bars changed to something more humane, so you have to alter the routing somewhere to make it work. Get the tank off and review the entire cable path for any sticky spots, sharp bends, etc.

It does sound like you need to sort out a throttle mechanism that's badly assembled or designed. There should be a definite stop built into the twistgrip mechanism. It's hard to give definite advice without seeing it in person, but I've sometimes found that some thumbfingered idjit has installed the throttle cable incorrectly. Even though there's just one cable on this bike, the throttle sleeve usually has two holes, and sometimes people misunderstand the mechanism and use the wrong one.

Throttles ain't nuttin' to screw around with. Please sort this out correctly so you don't end up dead!