why am I pulling 8500rpm now, and 8200 last year?

[chernoble]

Title says it all, I have noticed on the past 2 rides I have had the chance to WOT and look at tach at the same time. Holly sheep shat batman, 8500-8600 rpm. Sled is a stock 04 VE 800 except for a stinger and a gutted airbox. Last year it wouldn't pull over 8200rpm EVER! The only thing I changed from last year was going from stock Champion plugs to NGK Irridium plugs. Both days had different snow, weather and elevation. I am not complaining, the power past 8k is unbelievable, I just want to know why?

I was going to pick up some twins in the next couple weeks to waken up this motor, but now it's running better than ever! I am stumped on this one robin.

 

[chernoble]

bueller, anyone?

 

[KrazyKen]

Strange

The weird part is that you say that past 8k it pulls hard. Any dyno chart I've ever seen on this motor with a single pipe starts laying down at about 8000. I have the same motor with SLP single, air intake, VF3 reeds, etc. and I run mine right at 8000. And it runs very good.
Twin pipes like to run about 8200-8300.
I'm guessing that you might just have a tach that's not real accurate, and if it's the stock tach it's not unusual for those things to be as much as a couple hundred off.

 

[Robbie]

8500

Over the summer your spring in the primary has taken a "set". It isn't as strong as last year. Put a new spring in and your RPM will go down.

 

[KrazyKen]

Say what??

Over the summer your spring in the primary has taken a "set". It isn't as strong as last year. Put a new spring in and your RPM will go down.

A new (higher rating) primary spring will increase your peak RPM. When primary springs go soft you start to loose RPM. The spring is weak allowing the clutch to start and close prematurely at a lower engagement and close faster which results in a lower overall RPM.

 

[Robbie]

spring

You are right, I stand corrected

 

[chernoble]

A new (higher rating) primary spring will increase your peak RPM. When primary springs go soft you start to loose RPM. The spring is weak allowing the clutch to start and close prematurely at a lower engagement and close faster which results in a lower overall RPM.

And this is what has me puzzled...

so how would I accuratly measure my RPM if my tach is out? I am having a hard time imagining how it would loose it accuracy.

What if the sidewall of the belt wears down a bit, would this cause RPM to increase?

 

[KrazyKen]

You're going to have to either switch out the tach or install a digital tach. You might ask around and see if you could find a loaner from someone in your area to trouble shoot with. I have had this happen exept my tach was off more than yours all of a sudden. I also have another sled with the stock tach in place and a digitron as well and the stock lags behind a little.
I might be totally wrong in your case but you don't know if you don't check.
On the belt thing, I kind of doubt it but throw another (spare ?) on just to check.

 

[retiredpop]

Have you cleaned your clutches? I mean taking them off and washing the sheaves in very hot soapy water and then rinsing with clear water. Same thing with your belt. Use a piece of scotchbrite or fine emery cloth on the sides while washing to take the glaze off. You can easily get some belt slippage if the clutch sheaves and belt are glazed. While you have the clutches off clean up the weight pivot pins and the helix in the secondary. Maybe change the buttons in the secondary too.

 

[mod03rmk800]

X2^^
You may have a weight hitting the spider from wear. Check around your area and see if there is someone that can check your tach.

 

[chernoble]

I have not done any clutch maintance in the past 2 years.....don't yell at me, sorry, lol. I wll definatly do this next week, I did score a tach from an 02, I will use it this weekend on an ice fishing trip to check it, good trip to do so.

I purchased the repair manual recently, I am going to read clutching in and out this weekend.

Thanks a bunch for the advise guys, it has ran so well I have not wanted to change anything, guess it's time...

 

[polarisluvr]

clutch

sounds like you are a clutch person? will a stiffer spring on the top side give me more rpm?

 

[retiredpop]

sounds like you are a clutch person? will a stiffer spring on the top side give me more rpm?

Yes it will.

 

[polarisluvr]

clutch weights

thanks pop i think im finnaly learnin somethin!