06 M7 won't run full RPM We have checked everything we think

[Nolimits]

My nephew has a 2006 M7 153 with 8900 miles. It starts like it should and idles like it should. It will run up to about 7300 RPM and then drop off to about 6700 and then back up to 7300 and then back down again. It just continues to do this and never will run up to 7800-7900 like it should. We can watch the exhaust valve motor open and then close and open and close etc. It never stays open. We have checked stator, unplugged right side handlebar wires, unplugged taillight wires, checked reeds (with camera we have not taken them out and inspected). Removed the belt and ran it to eliminate clutch, inspected ground wire by taillight plug in. Once every 20 tests it will run up the proper rpm and run great. We will shut the sled off and double check things and next start it is back to its old self again. I have searched all the forums and have not come up with an answer. It does not seem to like to exhaust valves open, like the timing does not advance as they open. I don't what else to check. What are we missing?

 

[kamshaft]

My nephew has a 2006 M7 153 with 8900 miles. It starts like it should and idles like it should. It will run up to about 7300 RPM and then drop off to about 6700 and then back up to 7300 and then back down again. It just continues to do this and never will run up to 7800-7900 like it should. We can watch the exhaust valve motor open and then close and open and close etc. It never stays open. We have checked stator, unplugged right side handlebar wires, unplugged taillight wires, checked reeds (with camera we have not taken them out and inspected). Removed the belt and ran it to eliminate clutch, inspected ground wire by taillight plug in. Once every 20 tests it will run up the proper rpm and run great. We will shut the sled off and double check things and next start it is back to its old self again. I have searched all the forums and have not come up with an answer. It does not seem to like to exhaust valves open, like the timing does not advance as they open. I don't what else to check. What are we missing?

I had a skidoo 800 do that did that once and it was dirty exhaust valves. Even though they would open and close like they should they were gummed up and wouldn’t move as freely as they should have. It caused it too not reach into higher rpm and felt sluggish everywhere else. Maybe try to Clean the exhaust valves and throw some fresh reeds in it while you’re in there. Those M7 are pretty easy to access once you take the exhaust off.

 

[fltrsei97]

I’ve had fouled plugs cause this behavior before.
It’s an easy thing to rule out.

 

[Nolimits]

We did change plugs, and did remove and clean exhaust valves with no luck. I was reading last night about the rubber hose on the ecu. I was going to check that next and possibly the oil pump stuck. Also going to check the timing.

 

[concretebob]

If you're efi check fuel pressure.

 

[Nolimits]

Fuel pressure is were it should be. Put on a stock can and still no change. Going to check timing and tps resistance to make sure it is uniform. I don’t have an adjustment tester.

 

[Nolimits]

On the advise of a former AC dealer we put in a new stator, so far so good sled is running great.

 

[YTOuttaGas]

On the advise of a former AC dealer we put in a new stator, so far so good sled is running great.

Just wondering if it continued to run good. I have a similar issue. Doesn’t rev out all the way but….
If I’m on hard packed I can get it to 6500, downhill in powder is the same, but uphill in any powder and it only revs out till 3500. I’m thinking maybe the clutch?
Fuel pressure is 41psi.
Exhaust valves were pretty clean. And they moved.
New injectors.
Reeds look good via scope inspection.
Any help would be appreciated!
it’s a 2006 m7 efi 153.
Plugs are good.

 

[Nolimits]

Just wondering if it continued to run good. I have a similar issue. Doesn’t rev out all the way but….
If I’m on hard packed I can get it to 6500, downhill in powder is the same, but uphill in any powder and it only revs out till 3500. I’m thinking maybe the clutch?
Fuel pressure is 41psi.
Exhaust valves were pretty clean. And they moved.
New injectors.
Reeds look good via scope inspection.
Any help would be appreciated!
it’s a 2006 m7 efi 153.
Plugs are good.

The sled did continue to run good. We sold it at hay days this past year but was running good when sold. I would check both clutches for wear before replacing stator.

 

[YTOuttaGas]

The sled did continue to run good. We sold it at hay days this past year but was running good when sold. I would check both clutches for wear before replacing stator.

Not really familiar with clutches, where should I look for that wear??

 

[Readymedic]

If your not holding rpms, check your clutches. That's what it sounds like too me. Look for broken springs and that the weights are moving properly. Then, head to your exhaust valve motor. I have had to replace them before...then make sure that the cables on the motor are correct and running freely. I had a dealer before put a cable on back wards before. No rpms, no top end..then measure the cable for properly length, proper mm/inch. IF stretched, they won't react the same or even open or just open a little.