Bike damage/Cold weather????

Greetings THUMPS! Just wondering if I could damage my ride (2001 WR426) while riding this fall/winter here in Illinois?

Can it ever be too cold to ride or will I quit first due to frostbite or breaking my ARSE on a patch of ice? Thanks in advance for the feedback, can't wait until spring/summer!

Mark (highland, Illinois)

Mark, I live not too far from you here in wonderful Imperial MO! I have ridden in the coldest weather. I rode last year in about 5 inches of snow and ice down at St. Joe(Flat river). I rode last weekend in 35 degree weather and the only thing I noticed was when I first went to start my bike, I had no compression(no tdc). Once I kicked it a few times I had it and it started and I rode it the rest of the day with no problems. I think as long as you can handle it the bike can too! Just make sure you have anti freeze in the bike to keep it from freezing when you leave it sit.


Just a warning...

Double check your coolants properties, YZ-F heads don't take much freezing to crack, I have one that is cracked because of that reason.

Last weekends race started out at 29 degrees. I usually keep my bike inside my race trailer until just before time to roll out onto the starting line....My wife thinks I'm nuts because I crank up my propane heater about an hour in advance so OL Blue is nice and warm when I crank him up....I really hate the cold....but atleast I can ride year round.....Except for my tear down week when I lube/change all the bearings and adjust the valves.


Bonzai :)

Make sure that you follow the guidelines in the manual for your oil. Cold weather turns warm weather oil to sludge!

Also, it is also easy to "cold seize" your engine if you do not allow it to idle and slowly warm up. What happens if you jump on it and run when cold is that the piston heats up quicker than the cylinder--resulting in reduced clearance between the piston and the cylinder. Other than that, roost all winter!

When riding in temperatures of 50*F or cooler, I cover part of my rads with thin cardboard to achieve a safe operating temperature to avoid cold seizure damage and sludge formation and for optimum performance. There is no thermostat to control cooling but, by touching the clutch cover or the head, it's easy to tell if engine is running cold and adjust rad covers accordingly...I also use Amsoil's synthetic "0W40" motorcycle oil for best protection and extreme cold flowing properties...

Ived used Duct tape over the radiator shields to help the bike warm up in the winter. When Ice racing in the winter, without the tape on, the bike just wont warm up. It keeps poping and coughing because it wont warm up. Other than that rejet for the tematures and have fun.

My bike is a beast to start when the temps drop below 30deg. Make sure you let the bike idle for a long time to get good and hot b4 ridding. Ive fowled more plugs in the cold by not doing this and taking off b4 the bike is fully warm.


Try dropping your SJ (Choke Jet) from the stock 65 to a 55 in the winter...It made a world of difference for mine...I haven't fouled a plug on startup since I changed.

Bonzai :)

Here's what I do to protect my bike at low temperatures:

Under 50 degrees - Tell the guys to go on ahead, you'll be right behind them - check TV see if anything good is on and make the call.

Under 40 degrees - Race Ricky Carmichael on Playstation

Under 30 degrees - watch your new Jimmy Neutron tape from under the covers.

Under 20 degrees - begin hibernation.

Your bod and bike will both thank you.

Good topic!! :D

I've also noticed that I had no tdc at first but after a few kicks, it came back to normal and I was finally able to do my starting routine. What is the cause of that???

Thanks to every one who already provided advises and to those who will.

Math :)

What is the SJ Choke Jet. Were is it in the Carb.I go up a few sized on the main in the winter because of the denser cold air.


You are right about going up on main jet size to match colder, denser air. Running too lean may cause engine damage, as well as reduce power output. I don't know if an "SJ Choke Jet" is an enrichening circuit air or fuel jet but, a cold running engine tends to foul plugs. If it's still easy to start, richening the pilot screw a bit and a bigger main fuel jet should do the trick.

The SJ (Slow Jet) provides fuel to the circuit when you pull the choke lever out. It is located to the left of the main jet (recessed) down in the tube. If you start your bike when it's cold with the choke...and pull back on the throttle seeing black smoke from the pipe....the circuit is too rich and needs to be leaned out....This is one of the major factors causing plug fouling in winter.

Going up on the main does nothing but make things richer and more sluggish.....Have fun, this is the way most of us got our jetting education.

Use your manual to identify the locations of all the jets in the carb. If you don't have the manual, let me know and I'll scan and e-mail the pages you need .

Bonzai :)

Running rich on "choke" is normal. It is used to add fuel to start a cold engine. Half-choke can then be used to keep engine running and warm up, then "choke" should be turned off as soon as possible to prevent plug fouling.

Furthermore, if bike is well jetted for warm temperatures, more fuel via a larger main jet for colder, denser air is inevitable to prevent a lean condition.

Yea when its 10 degrees outside ya gotta go up in size on the main jet to keep it from gettin to lean. Although 4 strokes dont seem to be as sensitive to this as the 2 strokes are.

I know the jet next to the main that you are talking about. Isn't this the pilot jet?

Aside from rejetting in the winter my bike is running the stock jetting and runs great. I dont see any reason to fiddle with it. It starts and runs great in the summer. Its just stuborn in the winter. Once running and warmed up in the winter it runs great.

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