Gwbarm

Thanks for sharing, looks like a fun time. Im getting a little old for that kind of riding but like watching it. 👍

As i recall the motor controller, a very expensive part and no aftermarkets available, is activated by the CDI, and it absolutly has to have a good ground to operaate correctly, including the fan, the controller itsself may be grounded through the CDI, not sure, i am having trouble relating what i know to yours because the one im more familar with didnt have a fuel pump. I think what you are doing stripping the wiring loom and checking is the best way to find it, you can throw expensive parts at it all day long and still may not get it. You have worked hard at it i havent been much help, but good luck.

Yeah it does sound like a bad switch, you can take them apart and clean them up, but for this level of inconsistency i would just replace it . Aftermarket ones are fairly cheap and i havent had any problems with them.

I thought you might have already done that, just thought i would mention it. This is a tough one. You may be right about the fan controller, i would check all the connections very carefully at the controller and CDI for good contact. Is there any other problems going on other than fuel pump?

Agreed! None of these problems should cause it to only run for a few seconds and quit.

I would change the oil , change the fuel filter, check the differential oil, if really black or milky looking change that. Also replace spark plug.

Photo has been removed, what part are you referring to.

That sounds like piston ring blowby, how long since you did your top end job. If you are using synthetic oil it takes longer for the new rings to seat.

Which one had no resistance, primary should have very little maybe.3 and secondary should be between 6 and 10.

Sounds like a bad relay did you replace it and still wont work.

You have been busy, sparlplug coil sounds weak, should be between 6 and 10 OHMs, what does the book say about that. . Do you get a good spark at the plug.

Good you got it going, rebuilding the original has always worked best for me, and yes, no ethynol gas, i dont use it in any of my small engines seems to destroy rubber partts and initiate rust on the steel parts.

Valve clearance is rather concerning, was the valve adjusting screw loose, it should not have changed that much in 650 miles.Unless previous owner adjusted it I would reset the valve clearances to spec and see if that helps. That would definately affect compression because clearances could actually be less than zero. Not really sure how you fixed the computer or what was wrong but that could also be limiting your revs electronically. Never had much luck at fixing computers, when something goes out it could actually take out another sector then it hard to diagnose.

Many things could cause this. If it is oil fouling maybe rings or valve guides, hope its not that. If it is dry powdery fowling it probably flooding. I know its fuel injected, the only thing i can think of there is replace the injector, but before doing that i would run some fuel injector cleaner through it and see if that helps. The other question would be how does it run, good, sluggish acceleration, jerky accelertion. What im getting at is to properly diagnose i need a little more information on how its running. There may be other electronics involoved that control the fuel injector.

Good diagnostics, glad you got it up and running.