I have a 2000 Arctic Cat ATV 250 4 stroke. I bought it used and when I got it it would barely run. I pulled the carb and found that it was jetted all wrong. I got all the stock jets for it and re jetted it and it ran great. It had about 105 psi compression which I thought was a bit low but it started right up and ran great. I would top out aroung 40 mph which is fine as the speed limit on the trails in Wi. is 40. I had it for about 8 months and then it started to get hard to start. After checking it out I found the compression was at 30 psi so I tore into it. This is the first 4 stroke I have worked on. After getting it torn down I checked everything out and determined the rings were worn. The piston and cylinder were in great shape and so I just replaced the rings. I also found out that it had an oversize piston (.50 MM). After I got it all together I had 120 psi Compression and it started right up and ran great. The only problem I have now is it tops out at about 25 MPH. Any ideas as to what the problem could be? Could the timing chain be off a tooth or could the timing just be off? I did not set the timing after I put it back together as everything seemed to line up and it runs good with no backfire. It does seem that the engine does not want to rev and it almost sounds like a ping at full throttle and/or heavy loads. Any ideas would be appreciated.
