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Break-in Procedure

By jwidd,
in YZ400F/426F/450F/450FX

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Apprentice

jwidd

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I have had my new 450 for a week now, and am curious how other guys have broken their bikes in. My dealer said for the first five hours, no more than half throttle, the next five hours, now more that three quarters throttle. That seems like a long time. The manual states much less. Any suggestions? I bought another Yamaha for the reliability, among other factors, I hope to keep it that way.

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Veteran

BergArabia

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I went through this 5 months ago with an 05YZ450f..

I was easy for 20 mins then a bit harder.

changed oil and filter after just 2 hours. (Plenty of metal in the filter).

then rode hard and changed again after about 3 hours.

Regular changes now every 6-7 hours.

I have about 30 hours up now and it runs beautifully..

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Grand Master

Blutarsky

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Why do dealers and mfgs recommend break in procedures that are more likely to result in poor ring sealing? Because they want to minimize the possibility of a failure....even if it means a motor will be less reliable later on.

Rings need maximum pressure on the backside of the ring...forcing them into the cylinder wall and lapping them in. You only have 30 minutes or so to get this done. This means running the engine HARD out of the box.

Here is the method I used for my new bike.

*Use a Petroleum Oil

*Warm new bike up approx 2-3 minutes max...no more.

*Ride it around for about 5 minutes in 2nd or 3rd about 1/2 throttle and let the engine braking bring you back down after you finish your acceleration run.

*Shut it off and do a quick inspection looking for fluid leaks, etc.

*If all is well, get back on the bike and now ride it hard. Run the engine WTO from peak torque to peak HP. Don't over rev and bang the limiter. Its better to short shift a bit...but stay WTO. Coast down using engine braking. Repeat for 20-30 minutes.

*Change the oil and oil filter!

*Go ride like normal.

*Change oil and filter AGAIN at end of day assuming you put in a day or riding.

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Grand Master

sirthumpalot

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You have to be careful running an engine hard right out of the box. While everything is rough it gets hotter and if you stay on the gas too long, in a worst case might seize or break something. Happened to me when I got on one of my old bikes too hard too early after replacing the top end. Fortunately for me it freed up after it cooled for about 30 seconds and I got away with no real perminant damage.

Follow the manual and you can't go wrong. From memory, I think the recommended break-in for a 426 was about an hour long, and it is not just idling around the pits. If you get to the track in the morning you can be riding full speed by lunchtime. And don't forget; break-in is not only for seating the parts, but also for making sure there are no problems, such as bolts left loose, things way out of adjustment, etc..

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SureBlue

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You have to be careful running an engine hard right out of the box. While everything is rough it gets hotter and if you stay on the gas too long, in a worst case might seize or break something. Happened to me when I got on one of my old bikes too hard too early after replacing the top end. Fortunately for me it freed up after it cooled for about 30 seconds and I got away with no real perminant damage.

Follow the manual and you can't go wrong. From memory, I think the recommended break-in for a 426 was about an hour long, and it is not just idling around the pits. If you get to the track in the morning you can be riding full speed by lunchtime. And don't forget; break-in is not only for seating the parts, but also for making sure there are no problems, such as bolts left loose, things way out of adjustment, etc..

All moving parts are precision producud parts and oil-film covered, so it is a myth bearings and gears need to be broken in. The piston rings need the pressure.

I fully agree with Blutarsky how to break in ALL FOURSTROKES.

Remember all 4-stroke engines get an initial short brutal break-in already at factory assembly line. In case faulty or out-of-tolerance parts are assembled, the engines will explode during this procedure.

Sirthump, your old bike you broke in after top end rebuild, was it a 2-stroke?

Proper engine break-in has nothing to do with loose bolts and fine adjustments. Naturally you check all these like the liquid levels before you ride. The only part that gets seated may be your seat apart from the piston rings. Nothing else gets seated in the engine. It is all precision tolerance parts torqued correctly in oil bath.

Also, don't mix engine break-in with rider break-in. If you are new to riding or feel unsecure, let someone else do it for you. First 20 miles are most important for the rings to get seated properly. Just don't run it too hot. And never rev a cold engine, let it idle warm.

I know I know, this is a controversary topic argued about in hundreds of posts here... :ride::applause:

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Fizz

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BTW, i've been too the Husaberg factory (before they've moved it from Sweden) and the testing every bike went through, when they had completed it was like this: start, up on the dyno, WOT for a few minutes, then they've just shut the bikes off and shipped them ....

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