04 450 back fire

My new 450 is backfiring when i kick it over when its cold...or sat for awhile...whats wrong with it...this is the only time it backfires, it doesn't during decel or nothing..just on cold motor when i kick it over it pops...help guys..and thank you..

When I first start my bike in the morning if it is real cold I turn the throttle twice put the choke on kick it over lightly till the piston is at Top Dead Center then give it a stab and it almost always starts first kick.

If it is a little warmer like above 60 degrees I turn the throttle once before starting. if it still backfires turn up the idle a little.

try a higher octane fuel...do you wash the bike after every ride? the breather could have moisture in it causeing some hesitation...hard to say...


When you wash it, do you avoid getting water on the air filter? I've owned two bikes and when i wash them and get the filter wet they backfire when their first started. If there is water on the filter, take it off and clean and dry it as water in your carb can be bad. I own a YZ426 and i know the new 450's are the same way, the filter is almost completely ungarded from water. When you clean it, put rags in the grips over the side number plates and behind the seat. That should help you.

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