Backfire Galore

Hi, so i took my 2012 WR450 for first (very short) ride today to find and see whats happening and what needs fixing after the previous owner didn't properly care for it (problems expected, got it a little cheaper than the normal ticketed price). Now heres what happened, and i am wondering what the cause is.

-very hard to start, running a fresh oil (and filter) change and 95 octane fuel, takes 15 hard kicks to show signs of life ( tried fiddling with adjustment knob on side of bike, helps a little but still very hard to start.

- once started, backfires lots. I'm talking like every 2nd-3rd combustion stroke is a back fire.

- doesn't like to idle. Have to keep the revs on if you want to keep it going, if you back them off the bike will die almost instantly, but once warmer it idles for longer periods of time, but unexpectedly cuts out eventually

- because of enormous amounts of backfiring, it is hard to control as is very jerky on the throttle, lifting front wheel one second, then no throttle response the next, making it unrideable.

The bike blows no smoke, has heaps of compression and has new battery and all electrical systems seems fine. I am hoping that the problem is a combination of severe timing issues and valve clearances very out of spec.

Really don't want it to cost much ( i don't think it should need a rebuild, as done under 9k kms )

cheers for any educated opinions. :rolleyes:  :rolleyes:  :rolleyes:  :rolleyes: 



It sounds like either bad gas, or a contaminated/dirty FI system.


Pull the fuel pump out of the tank and clean out the filter

Pull the throttle body off the motor and remove the Injector.

Pressure clean the injector using rubber hose, solvent, and compressed air. Activate the Injector open and closed using a 9v battery


From now on, use fuel treatment in every tank fill up, and preferrable, filter the gas before it goes into the tank, or use a tank sock.

Hi guys


I have an 08 ( carb model) and sounds the same as what you have. In fact the symptoms are exactly the same as you describe.

This is when I was buying the had stood for 2 years.

The owner had the carb cleaned at the local workshop and came back still doing the same.

I bought the bike anyway ( I think the problem convinced the previous owner to sell - I wanted the bike because of low milage)

When I started working on it I found the plug was rusted to hell - cleaned things out , replaced the plug and all good !!

There is a drain hole on the side of the head that gets water in it when washing - if you don't warm up and dry out afterwards - this happens - told to me by other WR owners.


Not saying its the same issue - but you may have a bad plug / plug lead / connection backwards from the plug .


hope you come right

Edited by Tigershark

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