I bought a couple of 135Ds for my kids that were put into action yesterday. One runs great and has no issues. The other would start but not idle properly. I adjusted the only screw on the carburetor (I think it is the air intake adjustment) to make it idle properly (had to turn it almost all the way clockwise). As it warmed up, it idled faster and faster, so I gradually backed the screw off (counter-clockwise). Eventually, it was running great (or so I thought), but the whole process would start over anytime it cooled down. After reading more posts, I think the other screw (idle screw) is covered with a brass cap. This quad ran for probably five hours yesterday, with me backing the screw out as idle increased until it leveled off. Same story tonight when my kids got home from school. Turn clockwise to start, gradually back off as idle increased when machine warmed up.

The night ended when it got stuck in reverse. Would not shift out (I did read later to rock it back and forth, but did not try that yet). I drove it backwards to the shed and shut it down. I was able to get it into neutral when shut down, but it will not restart. It smelled quite hot, so I'm wondering if I didn't fry something with my tinkering with the screw. My son did ride it quite a while at high idle without stopping back to have me adjust the screw.

Where should I go from here? If it starts, do I continue to mess with the only adjustment screw I can access, or will I do some damage? Do I dare drill out the cap so I can get at the other screw? I know it is capped to meet emission standards, but I am not in California, so not sure if I would be crossing the line. Is the whole problem caused by a bad gasket? I admittedly know little about small engine repair...only what I have read in these posts over the last several weeks.

Thanks for any insight you can give me.

 

Quad started and shifts fine again, so now my only real problem is the idle. As I said before, it looks like the idle screw is capped, and adjustments can only be made to the air intake screw. When the quad is started, it will not idle. If you don't give it some gas, it will die. If I twist the screw that I can get at closed and then back it off about a half turn, it runs okay for a couple of minutes. As it heats up, the idle rises, and I have to back the screw off again. Takes about four adjustments as it warms up, then runs good. When it cools down, the process starts again. I don't mind having to do this, since I don't want my kid riding it without me around anyway for now, but am wondering if there is a bigger problem I should be addressing.

 

I'm not familiar with your particular model. I'm wondering if you have a manual choke, or is it automatic? If your quad has an automatic choke (bystarter valve) then perhaps it is not working.

 

It is a manual choke. It is just a bigger version of the other Tao Tao quads, with a supposed 125cc engine that is actually a 107cc. It has a little bit better frame so it can hold 240 lbs instead of 130 lbs. I'm guessing it's sucking air somewhere, since I need to just about close the air intake to get it to stay running, but am not sure where to look.