What is the corrert way to break in a new 400ex? I heard that that are supposed to go very easy on it for the first two tanks. Then I see this website www.mototuneusa.com/thanx.htm. At this web you are told to beat the living snot out of it or it won't seal propely. So what should I do? I don't want to wreck it the first day I have it.

 

Read the owners manual and forget what the other sites say. The owners manual will explain what to do. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Moto Tune never mentions "beating the snot out of it". They simply say that you should rev it mildly high, then let it decellerate, to make sure that the rings seat right. The most important point that they make is to make sure that you let the engine warm up before doing so.

Most highly regarded engine builders will tell you the same thing. Usually it's only the salesman, who probably doesn't even own a quad, that will tell you differently.

 

i would also rev it out a bit. i wouldn't tear it apart the first day but i would not baby the heck out of it either. i am a believer in making the rings seat properly.

 

Thanks for all the info!

 

I would just follow the manual also. I know I can listen to my dealer though because he races motorcross and is one of the best in my area. He is also the mechanic at his families shop.

 

I have heard it all when it comes to break in. I have built so many engines I dont think I could count them all. From my experience just drive the darn thing and dont worry . I have never had a single engine have any kind of seating problem no matter how the customer drove it. Make sure you change that break in oil and filter like the manual says and youll be fine. I hate to see people so spooked about such a trivial issue.

 

I just babied mine for a couple of days then drove the pi** out of it. And it is running as good as it was when I bought it.

 

The first 20 min of a break in are the most important...... Anything after that don't mean $hit. I also believe in proper ring seating.