This engine has a little over 900 miles on it. dax F80 that has always performed perfectly. Yes, I'm an Opti-2 (100:1) user and have always had good luck with it with this engine and several others. Today during a ride the engine suddenly stalled at a stop sign. Very unusual. Started right up when I pedaled away but stalled again the next time I stopped. I disengage the clutch at stops and it has always idled perfectly. I reached down, screwed in the idle screw a little and then found the idle was way too fast. When I backed out on the idle screw, the engine would die.
I rode home and started checking for the usual problems. Good fuel flow...the plug, an NGK B6 is clean, .025 gap...the choke is open...the air filter is clean...there is no air leaks at the carburetor, intake or anywhere else. I disassembled the carb, its clean. No probelm with the needle valve, jet and the bowl is clean. Fuel filter is full. Float level has not changed. If I screw the idle screw in far enough to get it to idle then the first time I twist the throttle it sits there and screams until I screw the idle screw back out then the only way I can keep it running is to continously blip the throttle. It will not idle on its own. I took the carburetor apart again and checked the slide for binding but it moves freely. There is no rough spots in the slide grooves where the idle screw or slide alignment pin rides.( I had a problem with that on another carb one time) Anything above idle speed it runs as it always has. It is and always has been the most powerful engine I've had and still pulls an easy 35mph...but will not idle. I checked both crankshaft seals, no problems there or evidence of air leaks. I'm running out of ideas here. I tried a new plug...checked the plug wire connections, I run solid copper core wire, and even tried a new CDI but the problem remains unchanged. There is no evidence of a head or cylinder to case gasket leak. Keep in mind this problem came on suddenly. It was not a progressive thing. I rode yesterday and it ran and idled perfectly. What the heck? Anyone have a suggestion?
Tom
I rode home and started checking for the usual problems. Good fuel flow...the plug, an NGK B6 is clean, .025 gap...the choke is open...the air filter is clean...there is no air leaks at the carburetor, intake or anywhere else. I disassembled the carb, its clean. No probelm with the needle valve, jet and the bowl is clean. Fuel filter is full. Float level has not changed. If I screw the idle screw in far enough to get it to idle then the first time I twist the throttle it sits there and screams until I screw the idle screw back out then the only way I can keep it running is to continously blip the throttle. It will not idle on its own. I took the carburetor apart again and checked the slide for binding but it moves freely. There is no rough spots in the slide grooves where the idle screw or slide alignment pin rides.( I had a problem with that on another carb one time) Anything above idle speed it runs as it always has. It is and always has been the most powerful engine I've had and still pulls an easy 35mph...but will not idle. I checked both crankshaft seals, no problems there or evidence of air leaks. I'm running out of ideas here. I tried a new plug...checked the plug wire connections, I run solid copper core wire, and even tried a new CDI but the problem remains unchanged. There is no evidence of a head or cylinder to case gasket leak. Keep in mind this problem came on suddenly. It was not a progressive thing. I rode yesterday and it ran and idled perfectly. What the heck? Anyone have a suggestion?
Tom