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Engine Break-In

21 posts in this topic

In principal, I agree with it. You should start and run the new engine for about 5~8 minutes the first time. Let it run near idle the first 30 seconds, then ride it no more than 1/4~1/3 throttle, and don't lug it down. Shut it down and let it cool.

Phase 2 is to fire it up, warm it up on the fly, and run it in a fairly normal, kind of relaxed style, with accelerations using up to 60% throttle for the next ten minutes or so, neither revving it to the max nor lugging it hard.

After another brief break, take it out for a 20~30 minute ride, beginning where you left off and finishing the ride by riding it as hard as you normally would. Maybe harder, if you just trail ride in an easy-going manner most of the time. You need to get several good hard pulls in there to force the rings to seat.

Change the oil. It's broken in at this point.

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In principal, I agree with it. You should start and run the new engine for about 5~8 minutes the first time. Let it run near idle the first 30 seconds, then ride it no more than 1/4~1/3 throttle, and don't lug it down. Shut it down and let it cool.

Phase 2 is to fire it up, warm it up on the fly, and run it in a fairly normal, kind of relaxed style, with accelerations using up to 60% throttle for the next ten minutes or so, neither revving it to the max nor lugging it hard.

After another brief break, take it out for a 20~30 minute ride, beginning where you left off and finishing the ride by riding it as hard as you normally would. Maybe harder, if you just trail ride in an easy-going manner most of the time. You need to get several good hard pulls in there to force the rings to seat.

Change the oil. It's broken in at this point.

Only thing I would add that I like to do is between phase 1 and 2 of this cycle is once the bike has cooled the first time go around and put a wrench on everything you touched...its a shake down and makes sure you got everything snugged up with no loose fasteners.....nothing worse than losing a fastener long about your first good ride because you thought everything was tight, but you missed one....personal prefrence...:worthy:

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...I would add that I like to do is between phase 1 and 2 of this cycle is once the bike has cooled the first time go around and put a wrench on everything you touched...
Absolutely.

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I've broken in 3 bike motors, 1 lawn mower, 1 weed-eater, 2 car engines, 1 snowmobile and 2 quads this way and have had very good results and no issues.

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thanks for the quick replies! one more question.... i know i shouldnt use full synthetic oil during the break in period, but is semi synthetic with ester okay? or should i just use plain petroleum oil?

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... i know i shouldnt use full synthetic oil during the break in period...
That's BS, plain, simple, and shrink wrapped.

It's one of the most absolutely inaccurate bits of mythology in the automotive universe, and it's just completely false.

Read :

http://www.thumpertalk.com/forum/showthread.php?p=3367478#post3367478

Then skip to:

http://www.thumpertalk.com/forum/showthread.php?p=3371654#post3371654

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The rings only take a few minutes to seat so to break in a new top end start the the bike and let idle for about ten minutes and ride. When you need to do all the break in steps is when you motor is all new top and bottom those step are for your valves, cams, and gears.

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The rings only take a few minutes to seat so to break in a new top end start the the bike and let idle for about ten minutes and ride. When you need to do all the break in steps is when you motor is all new top and bottom those step are for your valves, cams, and gears.

I disagree with this...I believe the steps are important in order to properly seat the rings...

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The rings only take a few minutes to seat so to break in a new top end start the the bike and let idle for about ten minutes and ride. When you need to do all the break in steps is when you motor is all new top and bottom those step are for your valves, cams, and gears.
In the first place, a YZ450 won't put up with idling for anything approaching 10 minutes, as anyone who owns one knows. Secondly, the cams and valves have no idea what the load on the engine is. They are affected only by speed.

While it is true that the rings in a properly prepped cylinder will seat very quickly, the piston is another matter, and needs a certain amount of conditioning to be broken in.

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That's my point though...Isn't the reason for running it very mellow for the first 2 heat/cool cycles for the piston, and then bringing it up to full speed on the 3rd to set the rings?

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"Very mellow" is the problematic part. Very mellow is a little too gentle. And the first step, you notice is half as long as the 10 minute idler would want done. One of the truly important reasons you want the first run short is so that any negative conditions can be found and corrected, such as getting to hot, loose parts, oil leaks, etc.

After that, you need to start leaning on it a little.

And a whole, complete brand new unit is different than one with just a freash set of rings. In that case, I would merge phase 2 & 3 together and cut the time in half.

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who remembers the pic of the older Japanese Yamaha employee -- I think it was on TWMX -- her only job is to start the motorcycle after it comes off the production line and put it through all the gears WFO on a dyno wheel (bike never moves). I'd be surprised if flogging it (smoothly anyway) would do anything bad at all.

but I can see that after dropping 7K on a new bike, I'd be cautious about break in too.

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You should see the UAW types roll your brand new Camaro out to the shipping lot, fresh off the assembly line :worthy:

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I'll add this -

Break-in procedures get a lot of lip time but something I've found (after several decades of playing with a number of ICE toys) that doesn't get talked about nearly as much is that they last a lot longer if you take the time to thoroughly warm them up before flogging them. A good heat soak that allows the components to achieve proper operating temperature (and therefore dimensions) goes a long way toward achieving a long service life.

Hey, the advice is worth at least what you paid for it. :worthy:

:banana:

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I'll add this :...they last a lot longer if you take the time to thoroughly warm them up before flogging them.
That's very true, and true regardless of whether it's the first time out or the 301st. You needn't baby them while warming things up, but you should at least allow the oil to get to the remote parts of the system before you put a load on it, and wait to really ride it hard until the radiator and the head are at least uncomfortable to touch.

Did you ever try to teach that to a 14 year-old?

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That's very true, and true regardless of whether it's the first time out or the 301st. You needn't baby them while warming things up, but you should at least allow the oil to get to the remote parts of the system before you put a load on it, and wait to really ride it hard until the radiator and the head are at least uncomfortable to touch.

That's the way I do it - when the cylinder is too hot to keep my hand on it then I get friskier with it.

Did you ever try to teach that to a 14 year-old?

I learned a long time ago that I shouldn't try to teach a 14 year-old much of anything - they already know it all. :worthy:

I wish I was 14 again - or at least be able to remember everything I've forgotten since that time. :banana:

:banana:

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Since I just got a new 450, I want to make sure I take care of it. How long should one wait before the different "phases"?

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