RPM Dropping From 8,500 to 7,500

SRX_700 said:
Well that didn't do it. Still runs up to 8,200 rpms and then back down to 6,800 after a couple of seconds. I cleaned and adjusted all the powervalves again and same thing, This is what I am now thinking the problem might be.

- Servo motor closing PV's at WOT after opening them (servo malfunctioning?)
- Floats in carbs need adjusting and/or carbs need cleaning
- Primary is shot (weights, bushings, rollers, spring, etc).

Any thoughts to this madness?
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There is no blinking of the temp light at WOT? Does the temp light blink 3 times when you start up the sled?

You could check the servo motor pretty easily by putting the sled up on a suitable stand, remove the cover and run the sled above 6500rpm. give it good WOT burst and watch the servo, if its erratic and moving the cables back and forth you have found your gremlin. That can be caused by the powervalve cables being adjusted too tight and from a faulty circuit in the cdi box,faulty servo motor.
 

mrviper700 said:
There is no blinking of the temp light at WOT? Does the temp light blink 3 times when you start up the sled?

You could check the servo motor pretty easily by putting the sled up on a suitable stand, remove the cover and run the sled above 6500rpm. give it good WOT burst and watch the servo, if its erratic and moving the cables back and forth you have found your gremlin. That can be caused by the powervalve cables being adjusted too tight and from a faulty circuit in the cdi box,faulty servo motor.
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Light blink 3 times when I start it. Last week the light was flashing at higher RPMS so I adjusted the servo and now there is no more blinking. Servo opens up under 900 RPM and closes above that without any twitching. I can hold the throttle at 7,500 RPM all day long and no bog (would rule out PV's and servo motor, right?). It's only when I pin it and hold it. After 3 - 5 seconds, it falls flat on it's face.
 
Yes I do. I am becoming increasingly frustrated diagnosing this issue. Primary clutch is next. I just ordered my clutch puller today.
 
Not sure if this helps or not regarding the condition of the primary but engagement RPM is 3,600 and the only sheave that is hot to the touch is the fixed primary sheave. All other sheaves are cool to the touch, even riding in 40 degree weather.
 
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when u guys refer to wraping secondary to degrees such as 70 or80 how do u cone up with degrees with a degree wheel i use the numbers like 6 and 3 or what have you 6 and 1 please explain
 
6 plus 3 will give you 90 wrap. 6 plus 2 will give you 80 (add the 2 holes up and multiply by 10).
 
Just a thought, but I had a similiar problem with my old polaris. It was a fuel problem. It would run great wide open for just a few seconds then start to slow down.

Turns out their was a lot of sediment in the fuel tank and it was clogging the filter. The fuel could not keep up the flow at high RPM's. Just another thought.
 
Good insight. I have narrowed down to the following issues:

- Clogged Fuel Filter
- Clogged jets
- Primary spring sacked
- Secondary spring sacked
 
SRX_700 said:
Good insight. I have narrowed down to the following issues:

- Clogged Fuel Filter
- Clogged jets
- Primary spring sacked
- Secondary spring sacked
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Update. I have narrowed it down to:

Clogged Fuel Filter
Secondary spring sacked

Running out out options here.
 
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SRX_700 said:
Update. I have narrowed it down to:

Clogged Fuel Filter
Secondary spring sacked

Running out out options here.
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The only fuel filter I know of is in the tank but the inlet screens or "top hat" filters/screens are often over looked. Another member here had similar issues and found the screens full of contaminates. They're located upstream of the needle/seat and are fitted in the inlet of the seat. I didn't read that you had looked at them yet or had the carbs off so you could check them and the reeds while you're in there.
 
snomofo said:
The only fuel filter I know of is in the tank but the inlet screens or "top hat" filters/screens are often over looked. Another member here had similar issues and found the screens full of contaminates. They're located upstream of the needle/seat and are fitted in the inlet of the seat. I didn't read that you had looked at them yet or had the carbs off so you could check them and the reeds while you're in there.
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I couldn't get the float pin out but there was a good stream of carb cleaner coming out from the needle when I squirted it into the fuel inlet.
 
SRX_700 said:
I couldn't get the float pin out but there was a good stream of carb cleaner coming out from the needle when I squirted it into the fuel inlet.
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I don't know that I'd rule them out without seeing them. Chances are they've never been serviced/inspected.

I've not used one but I've read here that a push-punch works real well in getting a stuborn float pin out. I think you can find them at Home D, Lowes etc...
 
I did notice with my Power Valves that they would open for a couple of seconds and then close, after a cold start, 30 seconds after starting the motor. Is this the servo motor cycling itself? Anybody esle experience this? You can definately hear the difference with the motor when they fully open at idle. Good crackling sound in the pipes.
 
sounds like the exact symptoms i had earlier this year. I know you already checked but mine was a stuck powervalve. Check your valves down at the valve, loosen the nuts and pull the cable to make sure it is not sucked and stuck in the cylinder....mine would run up to 8500 for a couple seconds and then down to about 7500rpm............pulled the stuck valve loose on the side of the trail then she screamed again.....a 5 min. fix..................just a suggestion
 
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