Hi,

So, I took the carb off the LT80 over the weekend and gave it a cleaning.

Now that I've reassembled, it starts fine. It seems to idle a bit high, and then when you give it gas, it revs up and goes, but then the idle seems to stick - when you step on the brakes, it finally comes back to down to idle.

The throttle cable seems to be fine - the spring seems to be forcing the thumb throttle back, so I'm not sure why it would stick open like that.

Suggestions on what I should be looking at?

Grant

 

Sometimes the rubber boot on the cable[at carb] can slide up this can cause cable not to get seated correct..

 

the slide sometimes gets stuck. is your bike running premix or do you still use the oil injector. sounds like it could be running lean on the air/fuel side... maybe move the needle clip down a position?

how is the slide is all the black teflon looking coating there all around or is it scratching off in certain areas? if the slide gets dry it will stick. but it should usually have fuel/oil on it I believe... at least mine does when it's not sticking, and I leaned it up a couple clips on the needle setting and it started sticking and I noticed it was dry when it was sticking... when I run it rich it doesn't stick at all lol. if it's really wet in there it would take more dirt to clog it up if dirt were a culprit I imagine... pull the cable out and if it doesn't stick at all you can pretty much tell if the slide is responsible or the cable or throttle housing/spring...

when mine sticks, it's the carb slide tho

 

IMO, Jetting and needle position has nothing to do with it.
Maybe it's leaking air from the screw on cap. Make sure the seal/washer is in place.
Make sure the cable is adjusted correctly.

 

mine got dry and was sticking as the thumb throttle would do it too and basically the bike just goes at that point. but when I pulled it apart it was dry and tacky feeling after I put the clip to a richer setting it went back to normal.. it hasn't stuck since, this happened while I was trying to set the needle to get the bike to perform it's best

just happened to me sunday so I suggested he look into it

altho running lean CAN lead to hanging revs, I don't think it's the kind of hanging revs he's getting. so I think it's just the slide getting stuck if you push the gas, it goes then you let off and the thumb leaver stays pushed it could be that. I've had two different carbs do it with two different cables (both new) I just changed mine recently within 2 rides and a month span...

I've checked everything both times that I could think of...

 

Thanks for the tips - to answer a couple of the questions:

- it still has the oil pump on. When we first got the quad, I pre-mixed, not knowing whether the pump was working or not, but after awhile I figured out that it was feeding, so I stopped pre-mixing it.

- there is still black (teflon?) on the slide, although some of it is scraping off.

- the thumb lever is not sticking - it goes back when you let off, but the revs stay up.

- in addition, it will also slowly increase revs on its own - what seems odd is that it seems to occur when I'm going downhill.

Looking at the online diagrams of the throttle cable connection to the carb, I'm wondering if I might be missing some parts. I'm going to have another look at it and take a couple of pics to post to get some feedback.

Cheers