How to break in your nice new 4 stroke engine.




The way I break in a NEW or REBUILT 4 stroke engine is with HEAT   CYCLES


I want to let you know now that this is not hard to do. It IS tedious and will take most of a day. After this procedure, your engine WILL be broken in properly.


You don’t see an Indy car driver going around the track at ½ throttle to break in the engine!! No, it’s all done on the dyno before that engine ever went into his car. I do the same thing with race bikes on our dyno and you can do the same with your ride.

Heat Cycles are what are done on a dyno to any new race engine to break it in.

The good news is it’s easy and simple to do.

The main thing you want to do is heat up and cool down the engine in a controlled manor.

Say you just put a new engine in aYZ450 dirt bike and you want it to last a long time and run strong.

Now I must clarify that this break in is for a BRAND NEW ENGINE that you or a shop just put together.

If you just got a new bike from your dealership, remember that the engine was put together at the factory and run on a dyno, than the entire bike was assembled and run on a dyno, put in a box and shipped to your dealer. They did the final assembly and maybe jetted it and took it for a test ride. Now you get your brand new bike. It HAS gone through SOME of this break in, so the very beginning of this is already done.

On a NEW or freshly rebuilt engine, make sure it’s ready to go-oil in it at the correct level, coolant full and basics.ign. and cam timing are set.

#1- Fire it up and keep it running at a low rpm-enough so it doesn’t stall for 5 minutes—DO NOT put it in gear or ride it, just let it run.


#2- After 5 minutes of running shut it off for 10 minutes.


#3- Fire it up again for 5 minutes and just keep it running.


#4- Shut it off for 10 minutes.


#5- Fire it up for 10 minutes.


#6- Shut it off for 10 minutes.


#7- Fire it up for 10 minutes.


#8- Keep adding 5 minutes to the run time but keep the 10 minute cool off time. If you put your hand on the cylinder after 10 minutes you will find it cools off quite a bit in 10 minutes.

What we are doing during this heat up and cool off time is getting the piston and cylinder up to temp, which gets them to proper tolerances—cold—a piston is not round—it’s tapered and out of round—at operating temp it is round.


#9- After you get to the second 15 min warm up, go ahead and ride it EASY-1st and 2nd gear only—for the 15 minutes, than the 10 minute cool off.


#10- You can now ride it for the remaining 5 minute increments until you reach the 30 minute ride time still with the 10 minute cool off.


You have now run it for two 5 minute times and added two 5 minute run times to each until you reach 30 minutes of run time with 10 minutes of cool off time each.


I hope this makes sense—you want to heat it up and cool it down-WITH OUT a big load on it until now.


NOW the fun part.


You should now be up to a 30 minute run time.


#11- On the second 30 minute ride, at about the 15 minute mark you want to put a full load on the engine—Here’s what is happening inside, All the new parts inside your engine want a easy break in and get to know each other—except the piston rings—they need to work to break in—So now the parts inside are warmed up and happy—now the rings.


#12- During the second 30 minute ride you should have your riding gear on and at the 15 minute mark from a fairly low RPM hold it wide open in second gear until near the rev limiter—this will only take a few seconds—now stay in second gear and let off completely, after the engine gets to a lower RPM, shift up and ride out the rest of the 30 minutes to get rid of the heat you just generated.


You just seated the rings against the cylinder wall and at full throttle with very little oil, when you backed off at high RPM you created a lot of vacuum to pull oil up past the rings and help rinse away very small particles of metal removed during this process.


#13- Now the 10 minute cool off.


#14- 30 minutes is the maximum amount of run time.


#15- On every other 30 minute run, See #12-  do the wide open portion and don’t forget to cool it off by riding out the rest of the time.


#16- I’ll do this until I use about ½ tank of gas.


I know this is a pain and will take you about 1 day, but your engine will thank you for a LONG time.


Now change the oil and filter, check the coolant and go have fun.