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Old 10-15-2016, 01:39 PM
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sbest sbest is offline
Motorized Bicycle Elite Member
Join Date: Nov 2015
Location: Nova Scotia
Posts: 248
Default Re: Cold start in winter 2-stroke

Originally Posted by BlueSmoker View Post
How is it to cold start those 66cc 2 stroke engines in between -0 and -20 celsius (35F to -4F)?
Do i need to have the bicycle inside at winter? Do cold start harm the piston and cylinder badly? Do the piston easily freeze and stuck? Is it hard to coldstart?
I have 40 years of snowmobile experience mainly with piston port type 2 strokes. Always kept the sleds outdoors. They will start and run even at -30, but of course, will start better if kept indoors. The oil tends to thicken up on the cylinder walls making initial start hard unless you are using a snowmobile type synthetic injector oil, which is formulated against this. Sled oils are your best choice for near freezing temps.

Forged piston (we have cast) are at large risk in cold temps. Cast not so much but always allow a warm up in any temp. Idling, especially with choke on, tends to foul the plug, so start up and start away on light load, taking choke off when you can.

Yup, coldstarting can be hard. Strong spark, good compression and right gas mix is essential.

Jetting NEEDS to be adjusted for temperature. Jetting that is spot on at 20c will destroy pistons at 0c. Need to richen up considerable for cold temps. Hard to believe that -20c will burn up pistons but it will. Every 10c requires a different jet setting.

This is from last winter:

I run sheet metal screws in the knobs of my MX tires on my KTM in the winter for traction on ice.

Hand guards, "lobster" gloves and full face visored helmet help. As do knee and elbow pads for the inevitable falls on ice. Hips take a beating too.
That's a mighty noisy bike you got there, it must haul a lot of ass?
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