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Old 07-26-2008, 01:32 PM
Jemma Hawtrey's Avatar
Jemma Hawtrey Jemma Hawtrey is offline
Motorized Bicycle Elite Member
Join Date: Dec 2007
Location: Essex, UK
Posts: 288
Default Re: Loss of Top Speed


Check valve gaps
Check spark plug condition - you want a nice light tan brown colour - anything else and you have a problem. Pale/white running lean (very bad) black and oily - oil blow by (not good) black and sorta sooty (engine too rich)
Check exhaust - while running it should be impossible to see anything unless the weather is very cold - black smoke at high/full power (too rich), blue smoke at anything over tickover (oil blow-by and combustion... bad.)
Check fuel supply for crud and or disassemble carb (DONT if you dont know how to or havent done it before, bits will go ping)

Check -

Brakes for binding - that will noticably affect top speed although it sounds engine related tbh
Check fixings and fittings

Do you have a speedometer fitted - if so do tests to see if you're down on speed or its just the engine bedding in makes you think so

Have you changed fuel suppliers or gotten it from a different garage - that can have an effect.

Check all intakes/outtakes are clear and operating normally - increase in back pressure.. not great and will stifle the engine...

Good luck

Jemma xx
"....Look, no pedals... *thud*..." The mating call of the motorized-biker.

"RetroEagle" - 32cc Two-Stroke, Piped. 35mph on #13 gear. Reversed stem with springer fork.
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