Whats the "PROPER'' way to break in my new 2-stroke?

[Kenny_smallz]

I just bought a new motor for my 85' atc250r, i'm telling you if it was run it must of been just for a minute, thing is super clean, anyway whats the best way to break it in..... ? thx

[just ben]

I do a few heat cycles with a lil extra oil in the gas,then I ride it like I stole it. It may not be the proper or best way but I havnt lost an engine I put together yet.

[Kenny_smallz]

Heat cycles?

[86ATC 250r]

after a top end rebuild i would let it run for a bit let it get warm and shut it off and then when it cooled down i would do it again. i did this a couple times. then i would let it warm up ride it around and shifting up threw the gears and then back down before the power hit let it cool down and i did this once or twice and then ripped it. i dnt know if there is an exact proper way but thats what i always did and i never had a problem. i always let my machines get warm before every ride.

[RIDE-RED 250r]

Yep, 3 or 4 heat cycles in the garage, then mix your first tank of fuel a little bit rich on oil. When riding with that first tankfull, vary the throttle, avoid prolonged steady RPMs. Vary the throttle rolling up to WOT in higher gears. After doing that for a tank full, it should be properly broken in.

There are many schools of thought on this topic, but this is break-in procedure recommended by the factories of every machine I have ever owned, 2-stroke, 4-stroke, sled or ATV....

[Kenny_smallz]

oh ok thanks alot, i mixed it 32:1 maybe i need to put a little more oil in it. i just rode it earlier for a couple times, 20 minutes at a time....

[Kenny_smallz]

the motor is suppose to be brand new. when i got it the rod going through the motor for the clutch wasn't catch so i took the side case off and the piece that connects to the rod and pushes the clutch out was on the other side of the clutch so i switch it around and now it works fine. run it for bout 15 min. killed it and the next day it would'nt crank and i felt and heard somehting rattling in the motor so i took the stator side panel side off and now the dang fly wheel bolt was loosened.... i took the fly wheel off and it had sheared the keeper so i put a new one on it and it runs fine..... so i'm happy....

[johnnytri-z]

ben6626 stole my thunder. less oil injection i dbl the recommended mix for the first tank and vary the rpm range dont run constant at one speed. i know the last 2 sleds i bought new [04 800verticle escape 08 M-1000] i fill the tank with gas and dump a full qt of blue 2 cycle in it but they have larger tanks, 160 hp. and oil injected. but this question will get 100 different answers, you get the same thing when you ask how to break in a gun....

[Kenny_smallz]

Lol I gotcha

[JasonB]

Thats how I have broken in all the air cooled motors I had; three heat cycles with accessive oil in gas mix, and then ride it like you normally would so the rings set

[4x4van]

I don't even run the premix richer, because that leans out your jetting (explanation below). For break in, I run the exact same mix as always, and vary the throttle without ever keeping it at one RPM for very long. I don't put it under too much of a heavy load, but I don't baby it either, running the RPMs up as high as normal but just for significantly shorter periods. After 1-2 tanks, I ride it normally; it's broke in.

If you run extra oil, you are in effect leaning out your carb jetting. Think of it this way: Your carb mixes a specific amount of air (through the slide opening) with a specific amount of fuel (through the jets, needle, etc.). Those are fixed volumes at every throttle position. Now the ideal carb jetting for air/gas mixture for combustion is somewhere around 16:1 (I forget the exact ratio, but you get the idea), however, the oil is not a part of that ratio, only the gas. The oil is used for lubrication only and not burned like the fuel is. So if you increase the amount of oil in your premix, you are decreasing the amount of "gas" in any given volume of fuel flowing through your jets, and still mixing it with the same fixed amount of air flowing through the slide opening. Less gas in the same amount of air = leaner fuel/air (carb) mixture.

So if you insist on running a richer fuel/oil mixture for break-in, you actually should richen your jetting as well to compensate for the resulting leaner carb jetting.