Throttle Issue?

[KnuckleBallz]

When I first got my bike a month or two ago I was having an issue with revs hanging in the 6ks after riding for a bit. I backed out the idle screw, and now I've got them to about 1500, which is fine. However, sometimes when coming to a stop they'll rise to about 4k or so. I've noticed that by easing the clutch out just into the friction zone, I can get them to drop back to ~1500 and stay there even with the clutch pulled all the way in. This isn't a consistent problem anymore, just on and off and I'm wondering if anyone has any idea what could be causing it? Could it be a throttle issue?

I'm pretty sure originally the dealer had just had the idle set really high because he was trying to sell it late winter/early spring. I don't think it has anything to do with the carbs (which they allegedly cleaned prior to my purchase). Any help would be appreciated.

It is an 09 with about 2k miles on it.

[mass-hole]

Check to make sure the throttle or choke cables are not binding and that they are adjusted properly. Does it rev up if you turn ur handle bars to one side or the other?

[KnuckleBallz]

As far as I can tell the handlebars aren't affecting it. I haven't specifically paid attention to that though, so I will next time I'm out. Although if you're up in MA like me, you probably know that won't be for a while haha. This weather has been miserable.

When you say binding, you mean like twisted/knotted up? Sorry, new to this stuff and don't want to make assumptions. Anyone know if there's another thread somewhere about proper adjustment?

[ryott52]

Check to make sure the throttle or choke cables are not binding and that they are adjusted properly. Does it rev up if you turn ur handle bars to one side or the other?

Same thing happened to me, turned out the choke cable was caught up around the steering head, causing it to rev.

[Trabmc1]

I am actually having that same problem I messed with the idle screw while my bike was in the paint shop recently and I got it same on finally but its revs up when I come to a stop even when throttle is all the way closed. Once I ease the clutch the same thing happens the bike idles down a bit but I'm also having a popping noise inside of the engine block like many backfires but only when I choke the bike and then take the choke off for a few minutes I get a popping noise as the bike levels out.

[KnuckleBallz]

Sounds like this is a pretty common issue then. I'll keep you updated as I work it out. I'm hopin it's just a cable though...

[mass-hole]

I dont know how to really explain it, cause when it happens it doesn't look like the cable is bound. I was having the issue for the second time the other day. I removed the tank and found out it was my choke cable and not the throttle, and it only did it when the handlebars were turned right. Basically I just removed the choke from the carbs, and adjusted it so it wasnt binding.

Oh yea and the weather has been awful. I took the opportunity to fully tear down my bike and get the frame powdercoated. Its a race against time cause I dont wanna miss out on the future riding weather.

[the wind]

I am in the same boat as the rest of you guys with my '05.  It seems like when the bike is just warming up the hanging throttle is slightly there to non existent, but when it is warm I have all the same symptoms. The throttle and choke cables seem fine with no snagging, so I went ahead and cleaned the carbs on Sunday and was able to reinstall them this evening.  They were very dirty / varnished thinking that this has to have been the cause to the idle.  Not so much, the cold start up is very much improved but is still sluggish.  I am at a loss on where else to start looking at diagnosing the problem, I want this to be solved since it does effect ride-ability and ticks me off at a stop sign.   

[ryott52]

I am in the same boat as the rest of you guys with my '05.  It seems like when the bike is just warming up the hanging throttle is slightly there to non existent, but when it is warm I have all the same symptoms. The throttle and choke cables seem fine with no snagging, so I went ahead and cleaned the carbs on Sunday and was able to reinstall them this evening.  They were very dirty / varnished thinking that this has to have been the cause to the idle.  Not so much, the cold start up is very much improved but is still sluggish.  I am at a loss on where else to start looking at diagnosing the problem, I want this to be solved since it does effect ride-ability and ticks me off at a stop sign.   

The idling issue could just be your idle screw not being set properly, last time i took off my carbs I forgot to reset the idle after I reinstalled it. As for the sluggishness, is your throttle cable properly tensioned and lubed?

[the wind]

The idling issue could just be your idle screw not being set properly, last time i took off my carbs I forgot to reset the idle after I reinstalled it. As for the sluggishness, is your throttle cable properly tensioned and lubed?

I did adjust the idle screw since it was idling at about 1500 rpm (I adjusted it when the bike was up to operating temp and running), I noticed that helped a little bit.  I believe the throttle cables are working correctly since I can hear them snap the throttle blades closed from handlebar lock to handlebar lock. I am going to check tonight if the intake boots are torn (I looked them over and visually they seem ok) I will spray WD-40 around them and see.  I did notice the boots that lead from the airbox to the carbs are ripped on the end,  I believe that they are sealing OK but am not positive.  Would these boots cause the slow idle return?

Keep the ideas flowing! I am willing to try anything. 

[ryott52]

Maybe, if they're letting in too much air it could cause the bike to run a little fast. If you let the clutch drag a bit when it's idling high does it bring it down? That could be forcing an opening in the boot to sort of suck close.

[ben2go]

Hanging throttle is a sign of a lean running engine.Clean the carbs and blow out the passages with compressed air.Mix screws need to be at 3 turns out.Floats need to be set at the mating surface where the carb body and bowl.Follow the jetting wiki for your set up.Buddha has jet kits.Back firing through the carbs is a sign of a vacuum leak around the intake boots or and ignition problem.

http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting and http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting-LeanOrRich?

[the wind]

Hanging throttle is a sign of a lean running engine.Clean the carbs and blow out the passages with compressed air.Mix screws need to be at 3 turns out.Floats need to be set at the mating surface where the carb body and bowl.Follow the jetting wiki for your set up.Buddha has jet kits.Back firing through the carbs is a sign of a vacuum leak around the intake boots or and ignition problem.

http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting and http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting-LeanOrRich?

Thanks for the links to the wiki, I will go back out to the bike after reading up a bit more.  I cannot turn the screws out since they are still capped and not drilled, I did check the floats tonight and I believe the float levels are OK.  I also did spray WD-40 around the intake boots and they seem fine no changes in idle when I sprayed them down...so it might be an ignition problem.  I guess it is time to bring out the multimeter...any hints on where to look? I did check the TPS last night and according to the haynes manual the sensor is within spec.

[ben2go]

Hanging throttle is a sign of a lean running engine.Clean the carbs and blow out the passages with compressed air.Mix screws need to be at 3 turns out.Floats need to be set at the mating surface where the carb body and bowl.Follow the jetting wiki for your set up.Buddha has jet kits.Back firing through the carbs is a sign of a vacuum leak around the intake boots or and ignition problem.

http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting and http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting-LeanOrRich?

Thanks for the links to the wiki, I will go back out to the bike after reading up a bit more.  I cannot turn the screws out since they are still capped and not drilled, I did check the floats tonight and I believe the float levels are OK.  I also did spray WD-40 around the intake boots and they seem fine no changes in idle when I sprayed them down...so it might be an ignition problem.  I guess it is time to bring out the multimeter...any hints on where to look? I did check the TPS last night and according to the haynes manual the sensor is within spec.

Give the coils a good check by the service manual and check the ignitor control box.Not sure where or what it looks like on the newer bikes.Check your connections to everything and make sure they are tight and corrosion free.Also check your spark plugs to make sure the little ring on the threads isn't bent or broken.

[the wind]

Give the coils a good check by the service manual and check the ignitor control box.Not sure where or what it looks like on the newer bikes.Check your connections to everything and make sure they are tight and corrosion free.Also check your spark plugs to make sure the little ring on the threads isn't bent or broken.

Thanks Ben! I checked over the coils and everything was within factory spec...the other night when I was working on it and I loosened up the throttle return cable, that seems to have about 80% killed the issue, I haven't had a chance to get out and test ride it since the weather has been so terrible.  I had a break in the rain tonight and took it out for about a 5 mile ride, yes the hang is still there but it goes down a ton quicker than before.  I think it was a combination of adjusting the idle screw and loosing up the return cable.  Once I have some more free time on the weekend I might toy around with the return cable some more. 

I did take out the air filter when we were working on the bike in the garage, my brother and I noticed that the left carb seems to be getting more fuel than the right.  It seemed that there was more fuel around the plunger needle on the left carb which also is the carb that sometimes backfires through.  Would more fuel cause a easier backfire? I wonder if the float position is just a little higher in the left than the right and would cause this. 

[ben2go]

Check this out http://gstwin.com/float_height_check.htm