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wrote:
have recently bought a KTM 125 motocross bike. I got this bike cheap
as it starts and runs but will not rev to its full potential. I have
fitted a new plug, stripped and cleaned the carb, decoked the exhaust
but to no avail. The bike starts first time without any trouble and
will rev up to about 1/4 throttle but any more and the whole engine
bogs down and will not rev any higher. By holding the throttle wide
open it puffs and splutters and tries to blow the exhaust off, I
believe this to be a backfire? does anyone have any ideas of where I
should be looking to solve this problem. many thanks. nigel.

Sounds like it might be a plugged exhaust system. I see you've "decoked
the exhaust", but have you looked for dirt dauber nests in the expansion
chamber or muffler, etc.?

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Gary Brady
Austin, TX
www.powdercoatoven.4t.com