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Old 12-22-2008, 09:34 AM
Airbuzz Airbuzz is offline
Motorized Bicycle Member
Join Date: Aug 2008
Posts: 49
Default Topping out at 20 mph...Too much fuel ?

Hi everybody. For the past couple of weeks my 47cc has been bogging down at 20mph. It will accelerate well to 19mph and then at 20mph it bogs down, dropping to about 18. This occurs whether you give it full throttle or partial throttle (just enough twist to accelerate to 20) so as to not flood it out.

The engine used to run fine. One of its sweet spots was at about 25-26mph. Then all of a sudden it started bogging at 20.

You may ask, has anything changed? I had to replace the float a few weeks ago. The original leaked. But I swear the bike ran fine for a while after it was replaced.

My saga continues and here is where it gets interesting. I was getting accustomed to the 20 mph top speed, so I just figured that Id allow my 10yr old son to ride this while I build a new one for myself. 20mph is fast enough for him.

Well yesterday he coasted into our garage on his ride and said he figured out the problem, stating that he was again able to hit the 25mph sweet spot. His method was to starve it of fuel by mostly closing-off the fuel shut-off valve on the fuel line.

The whole time I thought that it was not getting enough fuel. Now it appears that it was getting too much. Any Ideas of what I can do to fix it so I wont have to use the fuel shut-off valve method?
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