KTM 450XC - Yeti 129 FR build Q's

pm sent

1. what are people doing as far as air box removal/modification on this bike? Is the best plan just to remove the air box and obtain a aftermarket air filter set up to avoid snow packing in the air box?

A: If you are going back to dirt in the summer I would consider an intake. I like PST's Velocity intake. A cheaper option might be to buy another airbox off ebay or somwhere and cut the back, bottom off of it and use a prefilter over your normal airfilter. Gravity should keep it mostly clear of snow.


2. Do I need an aftermarket thermostat on this bike or is the stock thermostat adequate to prevent the bike from running too cold?

A: I would add a Thermobob 4 to the equation. Keeping the temps up is crucial for proper operation. Particularly for 4 strokes that are fuel injected.

3. Is there recommended modification to motor venting to prevent freezing and thus oil leakage from the valve cover?

A: A couple of ways to do this, I routed all my carb hoses and engine vent line to a foam block right above the swingarm linkage bolt, more or less on the back of the motor. This will keep the snow from accumulating on the hoses them self and insure proper venting. I used a skid plate foam pad from Works Connection to do this. You can also route the case vent up behind the rear brake master cylinder and orient it in a downward angle. This should work also.

Agree with all the above posts. Check out the C3 Powersports thermostat too, cheaper and way nicer install.
I have ran a KTM with the stock air box and I just took out my air filter foam and used only a prefilter. Worked just fine other than once or twice last year where I had to stop and clear the powder out of the airbox. Only was an issue on super deep dry fluffy powder day. C3 also has a nice pod filter if you choose to go that way and they do work very well.
As the other posts indicate, I rerouted my crankcase vent hose up and under the tank with the open end facing down. A bit of heat up in that area keeps it from freezing off.

If you ride cold areas with very dry snow, the airbox is more of an issue. We run a ton of KTM's with stock airboxes around here with our slightly higher temps and they are fine 95% of days.