carb and shifting problems atc 110

[kildeer]

I acquired a 1985 atc 110. I got it where it would run very good, idle perfectly, but it would only go in 1st gear in the low side. To make a long story short, I repaired the clutch so that it works pretty well (changed friction plates) but now having difficulty getting it so that it shifts smoothly. It changes gears all the way through 4th, but it shifts hard and ocassionaly you have to hold it in position. I adjusted the screw per manual specs, and through a range of minor adjustments. Some improve it somewhat, others make it worse. After repairing the clutch so that I could at least ride it, the carb started giving me problems. It doesn't want to idle. I can adjust the idle screw so that it idles good. Let it sit for a minute or so at idle, then it will rev up as though someone was opening the throttle, run at probably near 3/4 throttle for a minute or so, then return to idle. It keeps cycling like this as long as it runs. When riding, it does not seem to affect anything. I have pulled and cleaned the carb, checked for air leaks as best I could see, checked the air intake, and adjusted the idle and pilot screws (the only two I can find) per manual specs. The pilot screw has no apparent effect on the engine. The idle screw, with only the minutest movement has a dramatic effect. I suspect It is running rich since it now has some black smoke coming from the tailpipe where before it was blue, but not excessive. Any thoughts. One last comment, the bike had sat for several years before I got it

[shortline10]

People love to hold the shifter down and release it fast to pop wheelies and this is the worst thing you can do to the tranny , can cause all kinds of problems like your having . Could be as simple as the shifter linkage is loose or bent or as bad as a bent tranny shift fork . Pull the clutch cover off to inspect the shifter parts if all looks good its probably in the tranny .

The carb sounds like the idle jet is clogged a little still . Try putting the air screw at 1 1/2 turns and then setting the idle screw .

[kildeer]

I've pulled the clutch cover a hundred time (it seems, but at least 5 or 6) and found nothing wrong, the manual is not very specific and the illustrations are very poor as far as showing maintenance procedures (speaking as a former techinal writer and specification engineer who is critical of inadequate technal information). I guess that I have a transmission problem, unless you or someone else has another suggestion or alternative fix, even if temporary. I've also tried the idle screw and pilot adjustment as you suggested, same result. Also same comment on the carb, looking for alternative suggestions that won't cost a lot of money. Don't mind working the machine, just hate to put money into something that I only use to play around the property.

[shortline10]

I've pulled the clutch cover a hundred time (it seems, but at least 5 or 6) and found nothing wrong, the manual is not very specific and the illustrations are very poor as far as showing maintenance procedures (speaking as a former techinal writer and specification engineer who is critical of inadequate technal information). I guess that I have a transmission problem, unless you or someone else has another suggestion or alternative fix, even if temporary. I've also tried the idle screw and pilot adjustment as you suggested, same result. Also same comment on the carb, looking for alternative suggestions that won't cost a lot of money. Don't mind working the machine, just hate to put money into something that I only use to play around the property.


It sounds like a bent shifter fork then on the shifting problem .
Something else you can check on the carb is to make sure the boot between the carb and filter box is perfectly sealed . The atc90/110 need a little intake back pressure to idle and run correctly .

[kildeer]

Thanks to both of you