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How important is the break-in on a 4-stroke ?


I agree with the fact that there would be heat build up..a new engine is tight isn't it? as well as track wheels,etc.
 
Motoman doesn't say to run it WFO for long stretches from day 1.

His procedure is very specific and controlled with lots of short bursts of acceleration followed by deceleration.

I essentially agree with Motoman and Yamaha's break in procedure. Yamaha states no prolonged periods above certain rpms and motoman's procedure doesn't allow prolonged periods of high rpm either.

The real debate is how long does it take before running it WFO for long stretches is OK. Motoman says it is ready after his break in, but this is far less than Yamaha's.

With my RTX I followed Yamaha's break in procedure, but also followed Motoman's as well as you can on a snowmobile. I didn't do any prolonged WO until Yamaha's breakin period was complete and my motor hasn't burn't a drop of oil and so far has run like a top.

Who knows if this means anything, but for some reason my 07 RTX gets 10% better fuel economy consistently over the 06 Apex ERs I ride with. It also out accelerates them all and everywhere, except plowed ice, it has a better top speed. All of the sleds are 100% stock.
 
Our field testers have noted the new Nytro more than Vector and Apex, wakes up around the first oil change. I have posted about this on the blog with my own comments. The key is to avoid constant (long) throttle settings (at any RPM) and get those important break-in miles on before you start fine tuning... when in doubt, go by the book! cr
 
Absolutely 100% important.

Concur with all those that say to go by the book!

Yamaha must know, they built the engine!

Just give it some TLC and you'll see how the motor wakes up!!! ;)!
 
rightarm,
The main difference between a 2 stroke break in and 4 stroke break in, is the heat generated by a 2 stroke. 2 strokes are generally prone to running lean when the throttle is kept at a constant speed. A friend of mine just bought a doo 800x that the previous owner burned the engine up while cruising at 3/4 throttle across a lake. The constant burping the throttle on a 2 stroke is what helps to keep the pistons cool, and to keep the mixture from getting to lean or too rich, which usually will happen at idle, when they don't develop as much heat to keep an even fuel burn.
With a 4 stroke, you typically have higher compression ratios, and the ring sealing is more of an issue than anything. Just as everybody else has said here, there are a millionways to break in a motor, but varying the rpm's and allowing the engine to slow the vehicle will help more than anything to get the rings t properly "seat".
Engine techniligy has progressed so much in the last decade or so, and the qualit of manufacturing and materials used are so much better than they once were. This is making a proper break in period less and less of an issue.
I personally haven't heard anybody complaining about a motor failure due to improper break in for a very long time!
 
Very important on any engine. Let it warm up completly first and keep the engine at different rpm speeds all the time and make it work. Its as simple as that.
 
rightarm said:
I still don't understand the comparo between 2 stroke & 4 stroke break in,you can't compare apples & oranges.
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Still the same basic principles, which is seating the rings properly. It just takes longer on a 4 stroke.
 
Guys I was being sarcastic,I know the difference it's just that some seem to think that you can treat your 4 stroke like a 2 stroke during break in,which is insane heat cycles definately help both before riding but your 2 stroke takes about 150 km to brake in enough to hold it to the bar(about the same distance it takes to break in a new belt)where as a 4 stroke takes a hell of alot longer to break everything in and not just the rings.Valves,valve springs,valve seats,cams,crank,etc.All need proper break in if you want a non oil burning fast 4 stroke,My 03 RX1 didn't see sustained WOT until after 1600 kms,it was hard to stay patient and not get in too it especially when your buds are egging you on but it was well worth the wait.It never burned oil in the 4 years that I owned it and was the fastest stock 03 RX1 that I've seen.It held its own against many sleds 03 f7,07 apex,AC f 10 till about 1000 foot just to name a few,if you take the time to break in a four stroke you will be awarded ten fold compared to a 2 stroke break in on a 4 stroke.Just my. 02 take it for what its worth,but for the guy's who lost to my 03 wether it was on Scugog or at the track at the farm TRUTH HURTS DON'T IT BOY'S!

I followed Yamahas break in and then some.Regadless of what anybody says a consumer motor needs the longer break in period because of the closer tolerances.
 
rightarm said:
jim-bob said:
Old theory " Break it in slow and it will be slow--Break it in fast and it will be fast / later
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You said it "THEORY" AND THATS ALL IT IS.
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That's right, and I've seen it happen to a few of my buddies sportbikes, oil burners in the first year. Break them in hard and you'll pay sooner than later !
 
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