A little help for a YZ 2 stroke 250-timbersled

why ? Zee 1/4

Yup , built kit from ground up and put in on a 2003 YZ250 two stroke. I haven't workded all the bugs out of it, but will ride it more this next month.

So far:

basicly new engine crank piston cyl re nic'd boyseen rad valve fmf all good.

thermostat, big open tube air cleaner, no side panels, no fender, not enough torque to slog through alot of early season powder, light and great handleing, work in progress. Fur $600 I had the bike and now a big pile of leftover YZ parts.......need wheels?

Not sure if interested but ESR has both a 325 & 345 full top end kit for under 1K, also sounds like smart carb is the way to go.
Also see mtn-doo ktm300 build for ideas, sounds like it just rips.

The fmf sst series of pipes make a lot of power. Keeping the carb warm enough to minimize icing is key. Icing is the biggest obstacle you'll have

There was a pipe test in MXA last year, I believe the Pro Circuit pipe made the most power by quite a bit.

Smart carb or standard carb with carb heater

Stator to run carb heater and grips if needed

Cut the air box

Big Bore if you want to spend some cash

thermostat

Ride the crap out of it!!!

i've got a kx500 with a timbersled kit on it and an 09 yz250 i ride in summer.

some things i would do:
-premix your fuel and put a fair amt of de-icer in it. that helps with alot of the carb ice issues.
-get a real fine filter to keep snow out of your carb. i have one from boondocker and fine snow still goes right thru it in some conditions. polaris makes a white one thats finer and slips overtop. going to try that.
-get a water temp gauge. most places sell the small ones for $65 or so. i wouldnt mess with t-stats ect till you actually know what your temps are. a 250 is going to be wound out most of the day and making lots of heat. i bet your temps will be fine.
-ide put an intellajet or a vari-flow on your stock carb to start. if youre staying at the same elevation i would run the carb as is to start. maybe make a jacket for it and go a bit richer for the colder air.

on the 250 if you deck the head 25 thou they pick up 2 horse thru the entire range, but run good fuel. boysen rad valve picks up the bottom alot. PC 2 pipe picks up 3-4 thru the whole rev range. tested quite a few pipes on my 250 and the above was a good combo.

I'm setting up a snow bike on a 2006 yz 250 this year. Haven't been able to get it together to get it out and see how it does yet. I have big plans for next ncluding a big bore 325 or 345 with a nickelseal job for durabablity and a smart carb to pair with it. I want to source up a high output start to run some serious lights and some hand warmers too. I've found a couple small leads on 150 watt output but the majority I have seen are just a small mere 35watts. I read that their realibility aren't there either. Has anyone else tried to look into bigger power sources for the tried and true yz 250s?

We just test rode my son's 03 KX 250 this weekend. Carb was full of snow with the velocity stack. I put the stock air box back in and sealed it up for this weekend I hope it runs better. I will post the results.