breaking in a RM125

Yea go ahead and start it wide open on a new motor when it's dead cold and sieze it! :coocoo: If you was my friend you wouldn't touch my bikes if ya ever did that. You should do that heat cycle method and you don't chop the throttle you roll it on and off to keep lubrication constant. Do your friend a favor and not touch it :laugh:

For many years the "3 cycles of easy with a cool down in between" has worked for us.....NEVER have had a siezure, good seating-in of piston and rings produces the longest top end life possible. We mix our 125s at 32:1 and keep air filter clean.

3 heat cycle's with a rich mixture in the tank. In the RM125 Manuel it says "1 hour of 1/2 throttle and 1 hour of 3/4 throttle."

I break my bikes in a little aggressively but I break the riding sessions in 10 to 15 minute intervals to avoid excessive heat...The idea is to seat the rings without putting too much heat on a new motor and the short riding sessions help avoid too much heat...And always let the bike warm up a few minutes at idle speed when the engine is cold before doing any riding...Avoid the urge to "clean it out" as well.....During each 10-15 minute session I stay in the lower gears while varying the rpms and always do a few brief spurts at full throttle during each run while avoiding over reving it..Which means just enough time to allow the bike to blast through most of the rev range then immediately letting off the throttle...

I also like to break my bikes in on flat hardpacked dirt or a grassy area...The reason why is when you do a full throttle run the grass gives you very little wheelspin...say like if you ride on sand and go to give it full throttle and the wheel breaks loose the motor will spin up much faster and the bike will over rev (you want to avoid this)...Same is true if you're going wide open and the rear wheel comes off the ground..So I do break in on a flat hardpacked/grassy surface.

A couple of things to note...

1. Always let the bike fully warm up when the motor is cold.
2. Avoid lugging the bike (too high of a gear at low rpms).
3. Do a few brief spurts of full throttle...But avoid over rev and no constant rpms....Always be in a transitioning mode of accelerating and decelerating rpms.

I've broken in alot of new and rebuilt motors this way and never had any problems

I'm about to the point where I believe that the time it takes you to warm the bike up for the first time is all the time needed to break it in. I mean, what are we breaking in here??? Not a flat tappet camshaft that we must be very carefull with. Not a low quality piston that may not be in spec. Not a set of bearings with tolerances that may be too large. We are mating aproperly clearanced high performance, exacting tolerance racing ring to a cylinder that has a nicom, etc. bore finish. This isin't your car here?!?! A serious 125 race bike is going to need ring replacement about every 5 hours, with pistons at every 10 hrs. With most of your break in methods, the ring would be half way to needing replacing before break in is done.

Breaking in a dirtbike is pretty easy & basic.

Just start it up, ride it around in first gear at WOT for awhile until it can rev up cleanly without skipping or anything.

Now, head to the main ride (pavement), and pull up the front tire in a wheelie, then shift up into second when you are at the balance point, then 3rd, and so on. Don't stop riding a wheelie until the bike is in it's highest gear and has rev'd to the point where it comes down on its own.

After doing this about 5 times the bike will be broken in and ready for normal use. Just remember to pin it WOT and ride around in first gear as soon as you start it up untill it is warmed up, and you are golden.

Just kidding :) Sorry couldn't resist.

P.S. Don't foget to put a main jet in thats about 3 size's smaller, and only ride the bike when its extremely cold out, as that will allow the bike to run cooler. The colder it is outside, the better. And don't forget to use a main jet thats way to lean.

Sorry again LOL!!!