I have an 06 600HO that ran at 8200RPMs up to about 600 miles, but now seems to fade back to 7800 rpms. The sled is completely stock. I have checked belt deflection, also changed belts, checked exhaust valves. At this lower RPM the sleds top speed is only 90 and takes a while to get there. Has any one else had this problem and any suggestions to fix

were you running a premix for break in?

Check your motor mounts, drive and driven clutch springs.

Hello,
I see that your sled only runs 90 on your digital speedo.
I have to say that if yours is anything like my Firecat digital speedo (magnetic pickup), it is quite accurate. The lie-dometers that have always been on sleds to this point are 10-15% off. I suspect your new one is simialar to mine which has been shown to be within 2% accurate.
I would think that yours will not run over 90 unless you crank it for a long period of time on hardpack. Unless I go for a LONG time, mine will never run much over 97-98 in the trail, and I know it runs good compared to others.
By the way, my brother has a 600 switchback and that motor seems GREAT!

my new 600 ho is a dog too.... max 7900 rpm, barely 90 on a hard road run.. i sent it in to see if it could be adjusted.... unacceptable

you guys that are used to the old dream-o-meters on your old sleds are going to be shocked when u dont see the big speeds that your old speedos showed. my fuse last year would only show like 103-104 going accross the lake and my buddies rx1 was behind me and i was pulling on him slightly. his speedo was showing like 112!!!!! very accurate speedo.!!!!!!

Where's your jetting at? Is it stock? What is the temp your riding in? This sled practically has a race pipe on it and is a little finicky. I think the factory 420 main jets are conservative and may affect your rpm. I'm running 400 mains plus a Tempa-flow which adjusts the jetting even leaner when it's warmer. I would go to a 390 jet unless your riding at -20f alot.

Sounds like a loss of power. Older belys will tach higher as they break in. Premix would also not make as much HP and run lower RPM. Hope I'm wrong !!! Spring fatigue after only 700 miles makes no sense either, unless polaris has a bad run of springs. Which I doubt.

I would be dropping the mains 2-3 sizes, and running premium fuel only. Check the engine torque stop. And you did say a new belt was tried? How about plugs?

i was thinking about changing jetting... here's the way if feels... dogs from a dead stop, great through the power band, running 3/4 then hammer it and pretty unresponsive again... i am going in with it tomorrow morning, what would be the 1st thing to attack.. any advice appreciated... handles great, i'll be afraid to go on the lakes with my buds...

I think you're on to something there, I've said it before but didn't get much of a response on it.... The recall feature is BS cause it only takes one slip to spike it, but I'm convinced that while the track is putting solid force on the planet Earth, that speedo is dead nuts accurate.

Taking it all in, I think some egos have been bruised..... Back in the day I had an indy 650 that would peg the speedo all day long, that sled was nowhere near as quick as my 900.

I think that combo is supposed to pull 8250 RPM. Peace, beeler

Didn't your area experianced a fairly drastic change in air density over the last few days? I think you'll find jetting is the problem. Drop 1 or 2 main jet sizes and the missing rpm's will most likely return. :div20:

Yup.

These 600's are not dogs by no means,even the older 600's still run with the newer sleds.If you jet down correctly(mains,adjust fuel screws),align your clutches,belt to sheave clearance,adjust your suspension for your weight,track tension,etc....... all these little things help.

I have to agree with the speedo theory.
The sleds of past days have been giving our riders a false sense of speed.
Yes, you were going fast. No, you weren't going as fast as your speedo said you were!
Fyoushun has a good point!
:div20:

Rode a 600 Switchback this weekend that was way down on RPM too. Tach would swing to 8000 but then fall fall fall until it was pulling around 7100 RPM. Clutching was fine. Plugs looked OK but not great. No DET light flashing and engine temperature was perfect. It may be a leak in the VES system not letting the valves open or stay open. Will know this week as it's back at the dealer...

As the motor breaks in and seats, it will make more power. The slightests difference in power will overpower the cluthing and suck the secondary clutch open (upshift) faster than normal hense taking off at normal RPM's and settling at a lower RPM.

Fix it by tightening your secondary spring or putting in a stiffer spring to bring RPM's back to 8250.

If the motor had premix in it, it could slow the flow of fuel coming out of your jets and in essence lean your motor out and make more HP. That should've all been long gone by 600 miles though.

You might be getting a lean bog. Has it been colder when you ride? Check your plugs after a long 1/8~1/4 throttle run, at least a mile. If they are white drop your needle clip one notch(raise needle). If its really doggy in that 1/8 range and even pops a little, make the adjustment immediately. As for top end definatley make sure torque stop is no more than a few hairs away from engine block. Belt deflection very important, keep it tight. Make sure sled freewheels good too.

The stock clutching is pretty conservative in that the motor should be able to pull it. The thing feels majorly weak. I even took the secondary apart and replaced the red/black spring with one I knew to be good and added some delrin washers. No change. This motor can't be this weak. Something's not right. It felt like an 80 HP sled...

my first guess would be your valves. pull them out and clean them. i had to do this every 500 miles on both my 04 800 that now has 6200 miles and my 02 700 that now has 9200 miles. when they stick you can't hit the rpm up top and loose considerable power.
my 98 xc 700 without power valves had much more power and never had any valves to clean i hat the valves. last year went to canada to do a 1300 mile loop and had to stop at a dealer in lac st jean and the replaced my valves with titanium under warentee cost me 50 buck . next day the crank broke and the tow job to get back to my truck was $1400.00 it was 1 hour ride in a flate bead and then 8 hours in a pick up. we were at lac falion and the truck was at the cabernon.

It's not my sled. It's a buddy's. It's at the dealer. We suspect it's an issue with a leaky valve vacuum line or bad solenoid. Damn EPA-friendly valves...

What's the rate of the stock secondary spring? What's the rate of the spring you put in ?

I didn't even thing about the valves... yeah they could be gummed up and not working, or a torn valve boot??

The '06 has Solenoid-activated exhaust valves. I'm pretty sure that's what it'll end up being...

Ok, this post was started 6 days ago, dealer should have found the problem by now. Have you been told anything? On another thread SuperDave seems to be having similiar problems with his s/b 600.