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The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> ENGINE SUDDENLY RUNNING TOO FAST - CARB AIR LEAK?
Post Info TOPIC: ENGINE SUDDENLY RUNNING TOO FAST - CARB AIR LEAK?
Paul Rennie


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ENGINE SUDDENLY RUNNING TOO FAST - CARB AIR LEAK?
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Competing in vintage enduro yesterday and engine revs suddenly rose to run at about half throttle. Cables all ok and throttle returning to throttle drop screw. Completed lap by turning out throttle stop screw, but then the bike kept stalling at critical moments. Had to DNF. Carb recent overhaul, new cables, gaskets and inlet manifold, carb ultrasonic cleaned (by me). Fellow 4 stroke riders suggested an air leak somewhere - pump diaphragm for example? Cables are new and all was running perfectly as I ran the bike in (rebore and new con rod, big end etc) prior to enduro. Any thoughts please before I remove carb?



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Ttboof


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Hi

check the manifold between the carby and the head , the rubber tends to come away from the metal stubb they look ok even when there stuffed .



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Paul Rennie


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Thank you. I replaced the inlet with new when renovating recently. Problem was loose screw on throttle activation arm. Now all good

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The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> ENGINE SUDDENLY RUNNING TOO FAST - CARB AIR LEAK?


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