Cold weather jetting for Honda 450r?

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biohazard4253

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I have a 450r with stage 2 cam, K&N air filter, Full yoshi exhaust, and a fmf jet kit (175 main). Yesterday it ran great, temp was about 60. So i loaded it up and was gonna go ridin today, temp dropped down to 40. Got it off the trailer started up great, let it idle and warm up. Then when I was takin it down the road I give it alil gas and it cut out and died. I had a friend pull me and I pop the clutch to get it goin again, but it ran really sluggish and cut out alot. So I got it home took the spark plug out and it was jet black. My question is, when the temp gets colder should I go bigger or smaller with my jet? and if so how much smaller or bigger? Like I said im runnin a 175 main right now. And its an 05 buy the way.
 
first off awesome quad. umh yes 175 is a monster main jet. but you do not need to change it, just adjust your air mixture screw, you can buy adjustable ones, i built a pitt bike with a stock 102 main jet and i put a 132 main and in the heat it runs awesome! but in the cold it wont start. so your best bet is adjust air fuel mixture screw and ide probily change main jet, go to a 165 till summer again.
 
Normally you shouldn't have to rejet because of minor temperature changes and a 20 degree drop is extremely minor. If it wasn't, I'd be changing jets twice a day because here in the Midwest, that's the normal difference between daytime and nighttime temperatures. In very dry years it's 30 degrees.

It sounds like your bike is either running too rich or you left the choke on too long and sooted up the plugs. What was the orginal jet size? 175 sounds pretty big.
 
there are 450 trx 4 wheelers and 450 rx bikes, in any case either should handle from 100f down to 20f with the same jets. I would say its running rich , if you need it that rich get a hotter plug to reduce fowling. Just know your gonna have to warm it up longer when its cold.
 
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