I have a 01 Mountain Cat 600 EFI and I lost all top end power. It has no snap to it. It gets up to 6800-7000 RPMs and then bogs down to 6000. Maybe 40mph on the flats. The only thing I did to today was change oil to Shell Synthetic, did my chain tension and tighten my track(was racketing).
It was all good when I began then I started running it hard in deep snow. THen after about 20-30 minutes of that I lost all top end. I sputters and a bit of flame coming out the exaust as it spits at idle.
EFI wouldn't start it tonight. I need throttle to get her going. Any ideas or anyone know what the cause of this could be.
I just had it serviced and valve cables cleaned 100 miles prior.
Thanks

Cables might need to be adjusted,could be a broken reed valve ,my brothers ran like that with a broken reed

Do a Compression test on it, We had an efi do the same thing and it had low compression, We ended up doing the top end!

possible fuel pump if it is your looking at 350 buck a roos

I have about 400 miles on a new top. and 2500 mile on total. I am gonna do the com test tomorrow. I hear 120-130 should be aobut right. My mechanic says it could be the servo not getting enough power(short) or it's bad.

I got 118 & 120 lbs on my test. My servo was openning okay. Everything seemed fine. I had no boggin. Still had fuel left over in the can blowing flames after a hard run.
I fixed my thumb warmer(which could have caused a short) and changed my plugs and after 40 miles they were a nice brown color.
I gonna do some clutch and gear work to this week to get running at the proper elevation. Maybe have my reeds lookes at too.