I have to agree with the thrash from the start theory.
This is how I broke my Raptor in, ***** out from the start........

 

This is new to me........I have always been told to go ultra easy on your engine to break it in, am i wrong?

 

2-strokes generally, but 4-strokes are more forgiving

 

Let us know if it's like Pudljumper's, pin basically ripped out the bottom of the piston.

 

are you saying the oem Yamaha 2 stroke rings have less of a coating on them than the 4 stroke?

that is why you will seize a new engine if you run it hard out of the box.. ring clearances are extrememly tight and heat builds fast in the cylinder.

use a heat cycle method of break-in and you'll be better off ESPECIALLY with any high performance engine.

 

Its not the coating...... Come on. 2-strokes have to have a heat cycle to break in. So, when you buy a car which is a 4 stroke engine I bet you dont drive it over 30 miles an hour the first month right???? LOL!!!! That would be something to see.

Tell you what, call Sparks Racing or Craycraft racing yourself and ask them how to break in a 4 stroke. Sparks just slaps in the motors right from building them and onto the track, now with that said, have you heard of them not lasting a race? Bob just told me he shipped one to Oregon and the person was there waiting for his engine with his atv in hand and slapped it in and had no problems for the whole time he sand dragged it??

I dont want to be someone to argue till my head turns blue but do what you want. I am just stating this is how I have done all my bikes.

 

2-strokes seize on new top ends because like rap said, the clearances are generally tighter and when the piston heats up much quicker then the cylinder itself. this will cause the piston to expand before the cylinder, causing the tolerences to tighten up even more, thus seizing it

 

Raptorowner, I'm sure you think you are breaking things in right, but maybe Sparks tells you those things because of this....how can you break a motor in on race day? You CAN"T!! There isn't enough time in the morning before your moto's to properly break it in...that's why they just hammer down on a brand new motor..they don't care! If it fails they have the parts & people to replace or re-build the motor. I'm assuming that you feel what EVERY manufacture prints in there owners manuals about break-in is B.S. I guess they are all stupid for even wasting ink & paper on their break-in schedule. Auto manufactures DO say to take it easy on the vehicle for about the first 500 - 1,000 miles....things need to seat properly, or maybe they & I & a whole bunch of other people are just ignorant for breaking things in properly.

 

Better than my friends YFZ. He put the 13:1 in it and it snapped the rod causing all kinds of chaos. Yamaha fixed her all up though [img]i/expressions/face-icon-small-smile.gif[/img]

 

I break my 4 strokes in like I ride them.....and thats hard......and I've never had a prob. And most I know do the same w/o probs.

A few months back there was a link on here about breaking in bikes......