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2010 will not run

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We have 2010 250f that became hard to start, had to bump start fist time each day then would start normally. Valves fine all within clearance. Then becomes almost impossible to start, only bump start in 1st gear and would not idle, had to hold gas on to keep running. We have progressively done the following:

1. checked valves

2. checked cam timing, cam has been welded and cam has not slipped on gear

3. replace fuel pump (we have also swapped fuel tanks with other running bikes)

4. From a new bike we have progressively swapped every part including the wiring harness, throttle body, coil, capacitor, rectifier, fuel box, plug cap, spark plug etc.

5. swapped compete left case with stator from a running bike

The bike has spark, the fuel pump is pumping fuel when the bike is kicked over but plug is not getting wet. When kicking over it at best will have small backfire intermittently. We have swapped heads . When head was off cylinder looked good. Bike has 10 hours on it.

Will be pulling flywheel to see if sheared the woodruff key.

Any ideas would be helpful.

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We have 2010 250f that became hard to start, had to bump start fist time each day then would start normally. Valves fine all within clearance. Then becomes almost impossible to start, only bump start in 1st gear and would not idle, had to hold gas on to keep running. We have progressively done the following:

1. checked valves

2. checked cam timing, cam has been welded and cam has not slipped on gear

3. replace fuel pump (we have also swapped fuel tanks with other running bikes)

4. From a new bike we have progressively swapped every part including the wiring harness, throttle body, coil, capacitor, rectifier, fuel box, plug cap, spark plug etc.

5. swapped compete left case with stator from a running bike

The bike has spark, the fuel pump is pumping fuel when the bike is kicked over but plug is not getting wet. When kicking over it at best will have small backfire intermittently. We have swapped heads . When head was off cylinder looked good. Bike has 10 hours on it.

Will be pulling flywheel to see if sheared the woodruff key.

Any ideas would be helpful.

You could take it in and get them to hook it up to the computer, could be a sensor that is hooped. If its not getting fuel i would bet thats it. Throttle body sensor or even something pooched with the injection circuit. Or injector itself. With these bikes if you have a electrical problem you will pull all your hair out, take it in and get it hooked up. Or start unplugging things and checking the circuit.

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regulator/rectifier

Have replaced everything electrical and fuel related. Flywheel had not sheared the woodruf key.

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Have you checked out the injectors?

We replaced the whole throttle body with a new one from another bike. Removed injector and it is spraying fuel when you kick over the bike.

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looks like you have changed everything,checked to see if the mufflers plugged? not much left to swap.temp sensor changed?

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I Know this might sound stupid but is the oil filter clean, if so could it possibly be too much oil on it. I have seen this before same symptoms checked valves and timing and then the guy relised he had forgotton to clean his filter after the last ride, cleaned it then boom fired up and ran a treat sometimes it is the simple things. Good luck.

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I Know this might sound stupid but is the oil filter clean, if so could it possibly be too much oil on it. I have seen this before same symptoms checked valves and timing and then the guy relised he had forgotton to clean his filter after the last ride, cleaned it then boom fired up and ran a treat sometimes it is the simple things. Good luck.

Are you talking about the air filter or oil filter?

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I knew a of a guy that went through a similar thing. checked or swapped everything, spent weeks trying to figure it....it turned out to be bad gas.

He dumped the gas that was recently purchased, put in fresh and it started right up...........boy was he happy but pissed at the same time.

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When you replaced throttle body, and it didn't work, did you move the injector across with the throttle body, or just the throttle body, and then separately, just the injector?? Is it not worth trying to move both across at the same time....?

P.S. I hope the last guy was speaking about the air filter, because if I see too much oil on my oil filter, I just smile all day long... :smirk::smirk:

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When you replaced throttle body, and it didn't work, did you move the injector across with the throttle body, or just the throttle body, and then separately, just the injector?? Is it not worth trying to move both across at the same time....?

P.S. I hope the last guy was speaking about the air filter, because if I see too much oil on my oil filter, I just smile all day long... :smirk::smirk:

We change the throttle body with the injector at the same time, the fuel is renegade MX4 which we run in practice bikes and it came from a can we were using in other bikes that run great. we even took the tank from another bike and tryed it and no luck so don't think fuel quality is issue.

We use the Maxima pre oiled filters and use a new one every ride.

It is crazy, the plug has spark, the injector is spraying fuel and the cam is timed, the fuel box works on other bikes.

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Sounds like a busted flywheel key. Not firing at the right time that's why it backfires once in a while. I must have missed this one. Had an 09 KX250f that did the exact same thing.

Inquiring minds want to know?

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