Anybody have any 2-stroke break in suggestions?

[splatt]

I`ve been told or have read different ways to break in a new top end. I`ve been told break it in like you intend to ride it run it for so long let it cool down and repeat a couple of times. What I want to know is what is the most common procedures used. It`s a 94 YZ 250 with a Wiseco piston if that makes any differents. Thanks for any info that anybody can give.



Steve

 

[whyz]

I got this from a guy who helps me alot.> Spanky250<
But I repeated #1 a 3rd time because I'm a wuss. :confused:

Break-in procedure:

It's a matter of putting the new piston through several heat-cool cycles, and allowing the new bearings and rings to match the surfaces.

1. Start the engine and warm it up gently, with small throttle blips to keep it from loading up. The engine and radiator should be hot to the touch. No high revs! After it is completely warm, shut it off and let it cool completely. The engine must be cool to the touch. Be patient. Many people aren’t, and this is why the blow new engines, and usually blame the bike, the parts, or the mechanic that did the work, when it is really their fault.

2. Repeat #1.

3. Warm the engine, then ride it gently, using no more than 1/4 throttle, for about 15 minutes. No high revs! Let the engine cool completely.

4. Repeat #3, this time using 1/2 throttle.

5. Repeat #3, going to 3/4 throttle. After 15 minutes, do a couple of full throttle runs through 2 or 3 gears to ensure that rings are properly seated. Let the engine cool completely.

6.Re-torque the cylinder and head, they will loosen up during break-in. It is also a good idea to recheck them after a couple of rides.

7. Now you are ready to rip. Don't wring the snot out of the engine for the first tank or so of gas, and you'll be fine. It is recommended to pull the cylinder after break-in and sand any high spots from the piston, but I don't do this, and have never had any problems.

I probably use excessive caution with my break-ins, but I use forged pistons, which are very seizure-prone during break-in if not done properly, so I err to the side of caution.

Cast pistons are not as sensitive to improper break-in or warm-up, and that is why they are used as OEM equipment, to reduce the number of new bike warranty engine rebuilds from morons that buy a new bike and immediatly start reaming the engine for all it's worth with little or no break-in.
If you are not the type of person that will rigidly adhere to the break-in requirements demanded by a forged piston, or you refuse to warm your bike up properly before riding, then you aren't going to have a good experience with a forged piston, and you should stick with OEM or aftermarket cast pistons.
Later.

 

[RGalesi]

Absolutely perfect...

 

[splatt]

Thanks. I tend to be a little anal when it comes to breaking in a new engine. I`ve done automotive engines for about 12 years now but the break in is a bit different.

Steve