I've been getting a miss in this 400 2 stroke. Found oil on top of the head, so there must be a compression leak. Plus it has been running rough. It still starts and wants to move out.
Questions:
What small details do I look out for in replacing the piston, rings, gaskets?

Is there a special sealant to use with the gaskets?

Is there anything that needs to be done with the Jug?

Will I have to tamper with the reed valve?

Any tricks on taking the gas tank off?

Any tricks on the rings and the circlip installation?


I know that there are different sides as to staying with stock piston vs off brand manufacturers. The ATV is stock and not abused and would like to keep it stock unless there is an argument to switch.

Never took one of these apart but feel confident with some advice in tackling it. I have the manuel, so torque values should be there.

Appreciate your time and efforts in advance.... Thanks

 

I personally like the Wisco pistons for a Polaris rebuild. what you need to do is decide on weather your going to bore it or freshin it up (hone). First thing I`d do is take the jug to a machine shop and have them check the bore to see what condition its in. If your lucky you might get away with a hone job and then the stock size piston.
I`f its determined that a bore job would be best, you will need to get a new piston before the machine shop will do the job in most cases a .5mm over bore is what you will need to round out the cylinder.
The whole job is fairly straight forward and easy to do. There is no special sealants you will need however you will need a top end gasket set.
Here in Toronto the total job would cost around $200.00
30 for the gasket set
40 to 70 for the bore job (depending on the shop) look around and get prices.
and about 100 for a new piston with rings and rispin bearings (<-however spelled)
Again its an easy job and you will have a fresh top end.