2008 rmk 600 cfi loosing rpm

Had a similar problem, fixed with clutch springs, changed both with new stock springs.

Luvinit said:

Had a similar problem, fixed with clutch springs, changed both with new stock springs.

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What he said, sounds like incorrect/worn clutching.

I had similar symptoms with my wifes 08 600 RMK. It was binding in the primary. Bushing was ok..it turned out having a defective primary that was binding slightly on the bushing.

I have a carbed 600 that did the same thing. Rev right up and then drop rpm's to about 7500. Had the primary and secondary apart numerous times, align cluthces, new springs, and etc. Turned out for some reason, I needed to drop 2 grams on the weights. Ran great ever since.

monster said:

been having problem with my 08 rmk 600 ever since I've got about 400miles on it. my sled will rev out then all of a sudden drops to about 7400-7700rpm. been to the dealer numorous times they sad they adjusted the tps. but it still does the samething. if you let off and brup it it will rev back to 8200 then hold it then it cuts down to 7400, like one hole shuts down. if anyone can point me in the right direction it would be much appricated.

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My problem started at about the same original mileage. But I'm a flatlander so most of my riding is on trails in the 35 to 45 MPH and 5700 RPM range.

I won't waste time explaining all the other testing and evaluation we've done. What I have found that seems to be helping is eliminating a leak on the VES hose to the solenoid and actually plugging the drain side of the solenoid. Have 80 miles on sled without using the solenoid and am about 95% satisfied. Still need to do more riding but snow is not co-operating.

Interestingly enough, yesterday I found a new post on HCS where some guys were having similar success with this on their 800CFI's

http://www.hardcoresledder.com/forums/index.php?showtopic=412614

monster said:

been having problem with my 08 rmk 600 ever since I've got about 400miles on it. my sled will rev out then all of a sudden drops to about 7400-7700rpm. been to the dealer numorous times they sad they adjusted the tps. but it still does the samething. if you let off and brup it it will rev back to 8200 then hold it then it cuts down to 7400, like one hole shuts down. if anyone can point me in the right direction it would be much appricated.

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HELL I THOUGHT I HAD LOST THIS SO I PUBLISHED THE SHORT VERSION ABOVE< HERE"S THE LONG VERSION>

I think I found the problem with mine. Have 80 miles on and the sled seems to be better, I would say about 95%. Need to do some more riding to verify but snow is not co-operating. This is going to be a lengthy explanation, but I want to put out as many details as posssible.

After about 400 original miles my 08 IQ 600 CFI LX also started dropping RPM's. I did not notice it @ WOT I think because I'm a flat lander and do mostly trail riding in the 35 to 45 MPH range, This typically puts me @ around 5700 RPMs. My situation also would start after around 20 miles and get progressively worst for the duration of my ride. I even had the sled stall out on several occassions, and slow down to the point of being rear ended.

Whenever the dealer would ride it, ( even when I brought it right in while it was happening) they didn't experience the same condition test riding it. (tthought this 68 year was getting senile I guess) Finally I mounted my video camera and recorded 10 minutes of a ride after it started. You can see and hear the sled dropping RPMs while I'm not moving the throttle other than feathering when it feels like it will stall. I don't know how to post that video here but if anyone is interested I can put it on youtube and post the link.

Only thing Digital wrench ever showed was a TPS fault the 3rd time sled was checked. TPS reset and sled was good for 50 miles than started again. Different TPS installed and reset. After this change, now my sled is idling at 2500 which I questioned. Other sleds I've seen including mine before idled in the 1500 t0 1700 range. Same deal after 50 miles problem back again.

Now I'm not a modern electronic trained factory technician. I''m a shade tree mechnic that has been sledding since 1972 (just to let you know when you think I might be a little crazy)

The dealer asks me "What do you think?

I "think" that in this RPM range the sled may be in the critical transition stage of VES valve opening and changing from 2 injectors to 4 injectors. Now I can't do any remapping so I started looking at the VES. Polaris didn't have solenoid assisted VES until they came out with the 600HO in 2006. The 2005 and before were just mechanical valves. Problems we had with those were keeping them clean, some warping and breaking etc.

I disconnected the wirng plug to the solenoid and rode 34 miles without a problem other than the check engine light flashing.

I have my friends identical sled here that has 500 miles on and is running o.k. I was going to try his solenoid but as I started to remove mine I noticed the incoming "nylon" elbow was loose and showing oil around it. If it is leaking exhaust pressure while trying to open this I theorized could cause the lose in RPMs. I was able to tighten it about 270 degrees. To make sure the solenoid was not leaking I plugged the drain line with a 1/4 20 bolt that had a 1" solid shank. Reconnected the wires and rode 46 miles without a problem.

Interestingly enough, yesterday while I was checking the new posts on HCS I found this one regarding the problems with the 800 CFI and some guys having similar results on those.

http://www.hardcoresledder.com/forums/index.php?showtopic=412614

Maybe I'm not senile after all.

Seems a shame that if a computer can't identify a problem we have lost the ability to solve them with "old school" solutions

The flying vee said:

I have a carbed 600 that did the same thing. Rev right up and then drop rpm's to about 7500. Had the primary and secondary apart numerous times, align cluthces, new springs, and etc. Turned out for some reason, I needed to drop 2 grams on the weights. Ran great ever since.

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For some reason I and many others have noticed that the weights come in heavier than listed. I took my weights out before I even rode it and but them on the gram scale. Ground and balanced the weights so all three matched around 60 grams.

Lighter weights or gearing it down will compensate for the SLOW backshift from this secondary....A button clutch would hold the full shift out RPM better with the 600 torque curve

i had the exact same problem on my2008 rmk 600 cli. It has 1000 miles on it. It would rev up to 8050 and then backfired go down to 7200 7500 rpm. i couldn't figure it out. Tuned out it was the ECU. cost 400 bucks. but it fixed it.