Copy from amsnow
Some dealers should be out of buisness! There is no reason to blew 800CFI engine after the reflash. If the TPS is set Ok, no problem at all. But if, like many dealership, your dealer is to lazy to properbly check the TPS setting, because you have to remove the airbox and it take time on those 800cc, you can have engine problem. To properly set the TPS, many dealer think that they have to plug the labtop, look that the tps is set at 0.93-0.95 volts and that it. This is not the case, there is a procedure to properly set the basic adjustment for the TPS and it's CRITICAL for performance, fuel economy and durability.
Second, the exhaust port is not the problem. The one ring piston make no sens to me. It was nor working good 20 years ago and it's still the same. With a 2 ring piston, we should not have any problem with this engine.
Third, I would put my 2 cents, that many dealers don't even know that injector color means a lot when you reflash a sled.
Anyway, the compression of your sled is going down, have the piston change before to damage the cylinder (quicker for you to get your sled back)
Will let you know as soon as I have new about that new piston. For now, the answer I've received 10 minutes ago was that Polaris engineer are working on this issue.
Polaris parts and service manager
JG Busque inc.
Saint-Georges, QC
Canada