Limiter on QT50

Daniel Leasure /

I have been restoring a 1985 QT50 And was trying to get more power and speed on it I have polished the exhaust port,took out the small exit pipe in the exhaust and opened the hole up but there must be some kind of limiter on the bike for safety i would like to take it off or by pass it. it will run 30 but no more . and i know the power is in there it just cuts it off on the pipe . every thing else it runs great. Dan


Re: Limiter on QT50

too small and short ports, too small carb, and restricted airbox.

Stuff you can buy: Jemco pipe, Boysen reeds, UNI air filter, PW50 gear, Mikuni VM18mm carburetor, Holeshot clutch spring kit, if you want you can even do a 60cc cylinder swap

Stuff thats almost free: Added Base Gaskets, if you run 2 or 3 or maby even 4 you will raise the exhaust duration which will in turn increase your rpms, drill holes in air box and upjet, port the cylinder, loose weight

You can get parts at

Most of the stuff for a PW50 will fit your engine

by law they do 30mph

Fred Melonhead /

meaning ... in most US states ... the law limited 'mopeds' to 30mph

and they don';t put a specific part in to limit them

... as the guy above said ... all the parts that flow air are small on purpose - to meet the 30mph thing

Re: by law they do 30mph

stock qts need a 67.5 jet and a air filter instead of an air box... boysen reeds and run a bp4hs....mine with that setup did 35 all day long

Re: by law they do 30mph

You can't just tell someone what jet size they need unless you're in the same town and running the same setup, MAYBE. Temperature, humidity, altitude ALL affect jetting. So you can't just tell someone in another state to run a certain size of jet in their moped. They have to try different sizes to see what works. It may be close, but it's usually not the same.

If you're in KC, talk to Chuck and Matt from the Breakfast Mafia. Chuck's a girl, FYI. But they should be able to help you out with performance. I emailed you with their email address.

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