Well , heres the deal. My sled wont rev up, goes to about 5500 or so , then drops back to 4900 and wont go any higher, its spose to rev 8200 + or - 300, Thats what the manual said, my sled use to rev 8500 RPM.

K so i tried a whole mess of things and ill list them, if any1 thinks they know whats causing this please help.

- I checked compression 110 both sides
- I checked exhaust valves(not broken and holding pressure on the bellow when testing)
- I checked the reed vavles ( one or two are just starting to lift off the cages, maybe .20" off)
- I checked the carbs( no stuck needles or plugged jets, boots are fine)
- I checked the stator ( did an ohm resistance test, all showed up to spec)
- I checked the coil ( did an ohm resistance test, perfect)
- I checked plugs and wires (new plugs and wire are fine, i did a continuity test)
- I checked the air box ( nothing caught in it or anything like that)
- I checked all the wiring and hoses ( everything is connected and nothing falling off)
- I checked the fuel pump and lines ( no restrictions on the lines and throwing lots of fuel)
- I checked the temperature sensor ( ohm resistance test, showed up perfect)

I might have missed a thing or two, so my question is what would cause this with all of those things being fine, i just replaced head gaskets in my sled, one was kinda damaged and letting anti-freeze in my cylinder and was burning it. It started doing this the last day i was out, i noticed that when i went from reg to prem on the key switch it would top out 1000 RPM's in the difference, wheter or not that is any good info or not.I cant seem to find whats wrong at all my sled use to pin 8500 at any time before this always worked fine.

Its got me and everyone i talk to stumped , please help.

-Thanks.

Primary clutch spring is sagged out or broken.... 30$ fix probably. Had it happen a few times before. Might possibly be your crank out of index, but go through the clutches first.

yeah better check out the clutches sounds like a primary spring

CDI like I told you before. . . Have a brand new one, hit me up if you want it.

Primary spring like said.
110 compresion seems low, borrow another guage cuz it should be higher.
600 cranks can go out of phase and they HATE antifreeze.
Check the pipe for mice if it's been sitting.
Spray starting fluid on the seals while running to see if one leaks.

seperate the muffler from the pipe and rev it and see. muffler plugged up ?

Borrow a known good CDI to test with.

did you find your problem yet

check motor mounts then as others say replace clutch spring. I have seen a CDI do this but definitely do the spring first

CDI is easiest and cheapest if you know someone who has one you can borrow.
The spring would have to be broken to have that much of an effect, especially when it was fine one day and bad the next.
Sounds like CDI because the key switch is giving you an extra 1000 rpm. If the spring is broken, a timing adjustment likely won't give you more rpm.
You can visually see if your primary spring is broken also, so have a look at it.
Just my 2 cents.

Is there a difference between prem and reg key switch? Lots of good recommendations to check.

Like most of these guys said, I'd go through your clutches

I dont know if that sled has PERC reverse but if you hold the reverse button in for like 5 seconds or so it puts it in high alt mode. I did this once by accident on my sled and it wouldn't rev up for me while I was at low alt and it took me a while to figure out. just a thought