PROPER WAY TO BREAK IN 2-STROKE GUIDE!

We've been seeing this question asked often on Motocross.com so we figured we'd ask our own Moto814 on the proper way to break in a 2-stroke engine say after rebuild or even out of the crate.

From Moto814

1) Assemble the engine properly and torque all fasteners to specs.

2) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), shut it off.

3) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

4) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), shut it off.

5) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

6) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), take the bike off the stand and put it in gear. Take it for a ride. During this ride you want to keep the engine under a load at all times. Do not coast. Do not let the bike idle. Do not allow the engine to stay at one RPM. Riding on a mild slope is fine for this, as is slightly dragging the rear brake the entire time. Do this for about 15-20 minutes. Then shut the bike off.

7) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

8 ) Re-torque the head and base nuts.

9) Go ride.

The cool-down steps are crucial to this operation. You must let the engine cool completely for the break in process to work properly.

Also, do the warm up procedure I outline here before EVERY ride. Your top ends will last much longer if you do.

-Steve
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http://www.cafeshops.com/moto814

Cool Re-torque the head and base nuts.

Hahahah. What does "cool re-torque" mean.?

It means to re-torque while the motor is cold.

so you just mean re titen the head nuts now why would i do that do they get loose or something during the break in???

yz85ridr wrote:

so you just mean re titen the head nuts now why would i do that do they get loose or something during the break in???

During the initial heating and cooling cycles of the engine, the nuts can become tighter or looser. It's best to check them.

-Steve

Steve, I have a question for you.

How am I supposed to torque the front 2 cylinder base bolts on my 125? They are impossible to get to (except with an open ended box wrench), and there is no way for my torque wrench to even get close to them.

I didn't have this problem on my 80, so I don't really know what to do.

Edit: Steve, I remember you mentioning a crowfoot on your personal message boards to get to them...What is a crowfoot? And how much does one cost?

Motion Pro sells an adapter that fits on the end of your torque wrench that is made for those nuts.

I believe they cost less than $20.00

-Steve

im putin a new exhoust on to so that wont change the way i brake it in right ????

No it wont
Make sure to rejet for it though

"Also, do the warm up procedure I outline here before EVERY ride. Your top ends will last much longer if you do."

After you have broken the engine in why cant you just let the bike warm up from letting it sit and idle?

crhonda404 wrote:

After you have broken the engine in why cant you just let the bike warm up from letting it sit and idle?

You can, it's your bike. You can warm it up any way you want to. However, doing it my way will evenly heat the engine, and allow for maximum top end life.

Also, if the bike sits at idle, and your jetting is not spot on, it can load up.

-Steve

what exactly is jetting..and how do u no when to rejet ur carb?.

hey steve, the part where you said to re-torque the head and base nuts, what if I dont have a torque wrench? could I just tighten them with a ratchet?

thanks

moto814 wrote:

crhonda404 wrote:

After you have broken the engine in why cant you just let the bike warm up from letting it sit and idle?

You can, it's your bike. You can warm it up any way you want to. However, doing it my way will evenly heat the engine, and allow for maximum top end life.

Also, if the bike sits at idle, and your jetting is not spot on, it can load up.

-Steve

I have learned from experience that an unevenly heated engine wil cold seaze sooner or later. I do almost the exact warm up procedure for my bikes, and have allways , since the cold seizure, had excelent starting, and running bikes. My '93 CR125R that I just sold last week would start oby the 3rd kick on a cold engine, and 1st kick on a warm engine without fail. Probably needed a top-end in it when I sold it. The one thats in it now has been in it for about 6 years LOL, but I only ride about 20 times a year (not as much free time when you get older). Plus i change oil, and clean the air filter after EVERY ride.

Steve - would the same basic procedure apply to a 25cc 2-stroke gas trimmer? I am picking up a new one next week, and I want it to last as long as possible so if a proper break in will help it do so, then great.

BTW, I am concidering sending the cylinder in when you start accepting work and getting it ported