i am almost finished rebuilding my 400 engine, which i lost due to cold seizure [img]i/expressions/face-icon-small-disgusted.gif[/img] anyways, I had the case rewelded, and started from the bottom, replacing seals, some bearings, gaskets, piston, etc. How should I break this in. Wverybody I ask has a different method, and i dont know which one to believe. So, 400 owners, could you tell me how you broke in your 400s? Thanks alot

-DG

 

Make sure that you are jetted fat. Long warm ups. When you cant touch your cylinder head it is warmed up. In and out of the throttle all the time. Long cool downs. Hope that helps

 

Retorque the jug also, after cool down.

 

I put three hours on mine. 15-30 min at a time. Up and down on the throttle.
I also found that this was easier to do with the stock primary spring in it, That way you can get a wider range from low to higher rpms.

 

I second what everyone has said.

 

Oh yeh..I would go thru at least one tank before going full throttle

 

Ride it like your gonna ride it! See link

http://www.mototuneusa.com/break_in_secrets.htm

 

We always for the first tank of gas, took a paint can lid, and filled that little center cylinder(not the whole cap) full of oil, and dumped that in the gas tank.......just helps for a little more lube......

 

I also did something like that, I was mixing the oil and gas & and I still had the oil injector working.

 

If you premix and inject, just remember it will run a little leaner. More oil means less fuel and a higher air to fuel ratio. Shouldn't make much difference unless you are really jetted on the edge. When in doubt, richen it up a little.