Is it necessary to break-in new YZ450F?

Hi guys!

This is my first off-the-box motorcycle - 2005 YZ450F. I have read all manuals that I could find about necessarity of initial break-in for NEW bike. All manuals suggest break-in for bikes with serviced or modified piston, crankshaft etc. but no information about completely new bikes :naughty:

Can somebody help me?

Reread that section of the manual carefully. The breakin is the same for new bike, replaced rings, new piston, etc.

Don't thrash it, but don't baby it, either. Avoid lugging the engine at low RPM under a stiff load, very high revs, or extended full throttle runs. After the first hour, some harder runs at heavier throttle openings should be fine. Change the oil and filter after 2-3 hours. At the end of the 5th or 6th hour, it should be ready to rock. Change the oil and filter again, and at least every 10 hours after that.

The best break in for that motor is to do a few heat cycles with it in the garage. Start it up, run it until its hot (running temp) then shut it off and leave it until the next day. Once you do this 2 or 3 times, Change the oil then leave it until you run the bike. Once you run it, dont be scard to lug it in 2nd gear and so on. Do this for the first 15mins then drive the shit out of it. You have to put pressure on those rings for them to seat to the cylinder walls. I have done this lots on my 450's and never had a problem. Mine have always run strong and have dyno numbers to prove it.

If you dont believe me check this out.


Break in? Uh oh, I never done that before. Guess i've just been lucky.

If you read the manual it breaks down to this: 1st ride 15 minutes in 2 and 3 rd gear, no lugging, keep in mid RPM ranges. Allow to cool completely to ambient temp, 2 to 3 hours, and check EVERYTHING nuts, bolts, spokes, clutch, cable carb sdjustments, etc. 2nd ride 15 minutes, same as 1 st., and make sure you vary rpm, 3rd ride ride it harder, hard accel, but maybe not full throttle, allow to cool completely, and check everything. 4th 15 minutes ride it like you stole it, check everything and change oil with a good high quality oil like Mobil 1 MX4T. Make sure you change the filter and check the screen in the frame downtube, then at least once every 6 mos.

After all that the engine is broken-in, but the suspension takes about 2 hours of riding on an MX track. Be careful with your sag and fork height during this first 2 hours. I run the forks flush with the top of the triple until sag is set at 2 hours to prevent any unwanted headshake.


after the first 15 minutes let it cool down for an hour or so then ride it like you stole it.... it it sh!ts the bed thats what you have a 30 day warranty for.

Life is too short to waste time breaking in a motorcycle.

Just ride the thing.

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