breakin in during the winter?

[250rforlife]

ok well i just rebuild my topend this winter and i want to ride in the snow.i have a full fmf exhaust, uni filter, no lid, stg2 cam, 11:1 stock bore piston. im going with 165 main. position 3 on the needle, and 2.5 turns out for a/f. i wont check the plug if it runs right. but will me having my jetting off a little bit, and breaking it in the winter affect the life of this pistion.? the jetting i stated will be my summer jetting. anyajustments?

[DragonGunner]

Cold weather will keep it cool which is good. Your jetting sounds good, I would keep the lid on. Lots of opinions on break in...I always took it easy for the first hour an never got past 3/4 throttle. Sometimes I have let it run for short periods, then cool down, then a couple more short periods an cool downs. An interesting one I read came from a builder of over 30 yrs. who said the best break in was to ride the crap out of it after it warmed up the first time....the reason had to do with the rings getting deburred currectly, he said it doesn't sound right but its the best thing for the motor....I'm still not experienced enough to know if thats true or not...but when I rebuilt my KTM top end, I only had about 20 min. on it, did a oil change an then off to the first 45 min. long race, in the mud an ran the crap out of it...thats was its break in an its running stonger than ever after over 4 yrs. I would recommend changing the oil after a hour or two after your break in. Good Luck....what ever route you go its a 400EX so it will be OK...excellent motors.

[2001400exrida]

just don't cruise at one steady rpm.

when you're breaking it in, let the engine warm up, then go through the gears and take the rpm's through the range. don't rev the hell out of it but just go through the engine rpm's

then after about an hour, you're ready to go.

changing the oil is always a good idea too after a break-in