I'm new here and posted about installing a 72cc performance kit in the newbie thread:
http://www.scootdawg.net/showthread.php?t=56185
I had more time to work on it today, the K&N air filter came in, so I slapped that on, HUGH difference over the stock air box. The engine now revved up again and I got somewhere about 45mph out of it, however, not for very long.
I was doing a full throttle speed run for about a mile, then it just lost power, felt like I ran out of gas. I pulled to the side of the road, the engine still running, and idling well. I sat there for a minute to let traffic go by me, then took off, and had no problem getting back up to speed again. I again ran wide open for about a minute when the problem reoccurred. WTF ???
Now here's what I'm thinking, the fuel valve is closing under full throttle due to low vacuum, and the carb is running dry due to the increased fuel demand of the larger cylinder and jets. When I back-off the throttle, sufficient vacuum returns, the valve opens back up, and gas is once again free to flow into the carb.
Does this sound like a reasonable conclusion ???
And if so, is there a fix that doesn't include replacing the vacuum actuated fuel valve with a manual petcock ???