Does anyone know the general compression on the head for a 300 or 400 polaris?

 

the 400 is 120-125 psi.

 

So now a question of my ignorance. If I am running that low of compression 55 to 30 psi I would suspect rings. Now does the 2 stroke have any valves? I was initially suspecting a reed valve or something. I have been told that there are no valves just the ports in the cylinder walls.

 

No valves on the 2 stroke, chances are you're looking at rings or head gasket.

 

Thanks
I guess that doing the rings means pulling the whole motor off the bike to replace these or is there a better way. It seems odd that 2 bikes have this same problem with in days of each other. My 10y/o is riding the devil out my bikes and they quit on him. Is he maybe doing something to encourage this failure in the rings or head gasket.?

 

if its a 400 TB, Sport, Scrammy you can take off the gas tank and front fenders and keep the engine right in the bike, not sure about the other bikes, although im sure you could do the same thing

 

Thank you. I have done everything but complete disassembly. Any suggestions on parts supply besides Dennis Kirk or Rocky mnt atv?

 

Rick Ritter Rick Ritter
HPD HPD

 

Thank you for the time and info to all.