was tinkering with it to try to find the problem, I put a new carb on it, made sure there were no leaks in air box, made sure fuel pump is delivering fuel, it's clean fuel with new filters when I changed carb. I also replaced all the hoses on my 2010 buggy. I ordered a new coil thinking since it would idle fine and only lose power under power that it could be the spark, it's a new NGK plug and it was running perfect for about 3 tanks of gas. I've only used non ethanol gas in it since I put the new carb and changed fuel lines.
where it gets weird to me is if I plug off the air intake it runs fine (not completly but hold my hand over it) I found this out just in testing to see if the air box had a leak by covering it with my hand while holding the throttle open. to my surprise it started running right. I put a piece of duct tape over the intake and took it for a test drive, with 3/4 of the intake blocked it ran fine. I take the tape off and it spits and sputters with anything more than a tiny bit of throttle. any suggestions on what to try?
Well if she's running better with the air restricted/choked down thats similar to using the actual Choke to Add Fuel. Dbl.l your efforts on the Vacuum lines that are operating your fuel pump etc, I'm unclear if your full cap is vented or not but check it. If you do find the full pump is junk I would only recommend a genuine Mikuni... Good Luck..
Last Edit: Nov 24, 2017 0:42:09 GMT -6 by czmdiver
Check the jets in the new and old carb,,,I'm sure you'll find the new carb has smaller jets,,,I agree with diver your lean,,,if you restrict the air flow and it suddenly is running fine the machine is lean,,,have you done any other mods? Exhaust? Air filter?
Fuel cap is vented. It ran great with the new carb on it for hours. It stated to do this off and on until it just started doing it all the time. If it were a jet problem it wouldn’t be intermittent. I can see fuel pulsing in the fuel filter but doesn’t fill it. I think I’ll go ahead and order a fuel pump since all the hoses are new. If you think of anything else let me know. This is a wired one.