I just brought a Hi-bird 150cc QH-150ST from Anam Cycles and it run great for the first day. The second day I rode it and it started to stall at high speeds. It took couple starts to get it going, but after riding it for minute or so it would stall out again, and again. I was thinking maybe the the carb needed adjustment on the mixure screw turning it quarter turns, but stll no luck. I talked to a friend who rents ATV's and he mentioned that since we live in Colorado which I live is over 6000 ft. The carb might have to be rejetted to for higher altitude. I talked to Anam tech support (Daniel) and he mentioned to open the carb up and turn the jets 2 full turns to the left. I tried it and the hi-bird would'nt start up. It appears that the carb was over flooding with gas. The carb has two jets, one called Iding jet ,and the other called Accetatating Jet. I tried adjusting both, but still will not start. Does anyone have any ideas what this issues is, does it have to do with High Altitude issue.

Thanks
Dave

 

have you check your plug yet? how black is it? i'd replace it and see if it starts up and runs good again before fouling, if it does then you know for sure it needs to be rejetted but my guess it does, but replacing the spark plug and starting it will comfirm this. the 150's nornally uses the keihin cv clone carbuetors so your local dealer should have jets for it, the main is nornally a (113) is good for 1/2 to full thottle, the pilot or starter jet (38) is good for 0-1/4 thottle, needle jet is good for 1/4-1/2 thottle. you'll going to need to down size, higher alitude means less air, less air means you need less fuel. you need to also start again with the mixture screw out two turns, you have two screws one is a mixture screw the other on the float bowel is a drainage screw. so take the mixture screw screw and screw it in all the way then back off two full turns. if you have any ore questions you can e-mail me luvmysxs@yahoo.com

 

I figured out on what the problem is. It was the gas shut off valve from the tank. I noticed the spark plug and/or carb was not soaked with gas and I started to trace the gas line and noticed the gas was dipping out of the shut off valve. It should of been pouring out. I went to Home depot and picked-up a copper fitting to bypass the valve and now it runs like a champ. Anam Cycles sent me a new carb thinking it was a bad carb, but I fixed it before it arrived, so I have a new carb for backup. I don't want to tell them about the shut off valve, because they will probably want it back.
Should I leave it as is or get a new after market shut-off valve?

Thanks for giving me idea on where to start.
Dave