Slows down after a while

my last post was on the bigger carb, and i want to thank everyone for the help. It seems like it actually is running faster, but only after it has been sitting for a while. it seems as though after running it for a bit, it dosent go as fast. im guessing this is due to the piston expanding in the cylinder, or some how the heat is affecting it. What might be the casue, and is their a remidy?

Re: Slows down after a while

Hi! Blocked exhaust,Too little oil in gas, too lean a mixture,float chamber vent hole blocked(if it has one), and did you check what Chris said about too much crankcase oil? Prime suspect! BYE!

Re: Slows down after a while

Chris Robertson /

Check your air filter after a run where you've lost your top speed. Is it soaked in gas? Sometimes carburetors kick a little fuel out onto the air filter. As the filter gets soaked in gas, it begins to block the air flow into the engine enriching the fuel/air mix and reducing power. After the moped has sat for a while, the gas evaporates, and everything goes back to normal.

Does your engine start to four-cycle (i.e. drop in pitch and lose power at top speed)? That's a pretty common symptom if this is your problem.


Re: Slows down after a while

i know that this is a no-no, but i dont have a filter on it at the moment. Aparently, the moby has been doing over 35 mph. My speedo says im not getting it past 30, but i was just followed in a car, and i guess it was moing pretty good. With the racing carb, and a few other things done to it, it seems to run pretty well, and at this time, im am pleased with how its goin. thanx for all the help!

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