I tore the head off of the 400 scrambler tonight and I have a couple of questions.
1) What the heck is the small hole in the cylinder wall thet leads to the exhaust port do ? This is a new one for me.
2) Do you guys absolutely swear by polaris head gaskets ? Because the atv was rebuilt less than a year ago and it has blown an OEM gasket. Matter a fact, to tell you how much it has been ridden,it still has the crosshatch marks in the cylinder walls.
Thanks,
D.

 

The hole is a compression release to ease starting .

I swear by the OEM gasket . They rarely fail . Was the head you are using cut on to raise compression at one time ?

Rick

 

I don't recall as it was just rebuilt when purchased.
D.

 

gotta make sure the gaskets the right side up, so the small hole is in the right spot. i think thats the most important, more so than brand of gasket.

 

I also heard the OEM is the best to use. Do you do heat cycles after rebuild?