I installed the black spring, what a mistake! I've noticed no increase in low end and mid range/top end now seems very weak. Engine also seems to be revving higher with less power. Higher rpm's=more gas. Is there anyone here that REALLY KNOWS how to clutch the P650? Will the RED primary spring help or should I just put the STOCK secondary spring back in? Being a harcore sledder, I know what a properly set up clutch can do performance. I just don't have the required understanding or experience to invent my own set up. How can you troubleshoot clutching without a tach, anyway?

 

black spring doesn't boost low end or mid range, it's for increasing belt life.

 

You can try using a P360 belt on it for now. Others of us did mods to make the engine perform a little better at those higher R's.

There is an adjustable weight solution out there that can be made to work for the 650. Shotgun knows where to get it.

Fireman is right about the reason we are using the black spring. Belt life. It also helps crank bigger tires.

You can call EPI and they will try to sell you more stuff.

 

sledhead....what size tires are you using? do you have the stock tires?The reason I'm asking is because I bought the black spring for my my P650 , I haven't installed it yet because I am still using the stock tires.I don't know if I'll go for bigger tires or keep the same size when the time comes to upgrade...but after reading what you are going through....I am beginning to think that the black spring might not be an option.
Get back to me or post what you have figured out what your next move will be.

 

I'm still not totally sold on the black spring yet myself...I just replaced my 1st belt at 1100 very hard miles ( more than acceptable distance I think ) with stock springs, most of these miles were run with a set of 26" mud runners... I work my quad, play with my quad, mud bog race with my quad, & have run a few hare scrambles with my quad... if you keep your belt tight, us low range when towing, or climbing hills, there is no reason why you won't get at least 1000 miles on a belt...IMO, the black spring, with no other mods, unbalances the way clutches work with each other, & can negitively effect you top speeds...WAM

 

The black spring aids in belt life by back shifting quicker insuring the belt is at the right position at all rpms. You wont notice any gains for the most part. But when you run the red and black spring together or even just the red primary you get great performance gains.

 

I would rather get weights to accomodate the black spring than remove it. I have had bad belt slippage with the stock spring and the black spring also reduces pulley wear and belt heat.

We have to be careful about just calling EPI. EPI is smart, but somehow they sold somebody around here some 56g weights, and it slowed his machine down even worse. That makes the problem worse. We need heavier weights. We don't just need them heavier, we need the weight proportioned so that it affects mainly higher rpm stuff, so that the low speed is still powerfull.

I think we need more weight on the end (not the middle). Any technical gurus confirm this? I can't see my drive pulley now to confirm this. Maybe I can drill a hole and fill it with lead.

 

NYROC... I've been thinking the same thing...I cast bullets, & have alot of lead on hand... pictures of SHOTGUNS adjustable weights got me thinking about melting lead into the holes... I wish the weights didn't cost so much, I may just have a set machined, to expirement with, I think there are very many variables to try...i.e. more weight on the leading edge / trailing edge...shape, or amount of curve, & placement of the weight from the pivot point etc... sooner or later, some of us with the technical aptitude, should hook up & iron out some of these issues... who better than "us enthusiasts"...WAM

 

Someone help here, I've been told the 360 secondary is different than the 650, the 360 is supposed to be close to the EPI black but not hardly as stiff, meaning it will grip the belt a little tighter than the 650 stock spring but not as much as the EPI so performance doesn't suffer from useing the 360 spring..... Anyone know for sure about this, We may need to go to the Kaw dealer and buy a 360 secondary and try it, what does everyone think.......

 

I had the 56g weights, as per EPI's recommendation for my machine, tire size and weight, and mods. The problem is not only the weight of the weights, but the shape. BTW - if you tried EPI's 58 or 60 gram weights the problem would be worse, not better. It works as follows: if the shape of the weights is the same but you make them heavier, they swing outward with more centrifigal force and force the primary clutch to close faster and sooner. The result is a faster upshift and this reduces the engine's RPM's. Heavier weights are not the way to go if you want to run at a higher RPM.
The contour of the weights is the key - we need to keep the RPM's at or about 6500 without climbing way over that point at speeds over 40mph. That's why I tried the EPI weights; at 35-40mph the RPM's would climb to 7200 (out of the powerband) and stay there until the clutches were shifted out completely at which point the RPM's would slowly climb to 7700 (the start of the rev limiter).
I went with EPI's recommendations and put in the 56g weights and black and stock springs (and every other combination I could come up with to try to make it work). They said the weights would correct that very problem - they would hold the RPM's down in the powerband longer. Unfortunately the RPM's went down to 5500 and killed the engine's performance. The red spring got the RPM's up to 5800 - still too slow. The good people at EPI refused to take back the $125 weights; I had already installed them and even though they didn't work as advertised, they were non-returnable. It's a long, sorted story that I posted in another topic so I won't get into the sorid details. [img]i/expressions/face-icon-small-disgusted.gif[/img]
I started drilling holes in the weights and was able to get to 6200 RPM's - still too slow and upshifting too quickly. I got to 3 holes per weight, a 4th made no RPM increase. So my next step is to put the weights on a mill and begin softening the contour a little at a time to gain control of the RPM's. BTW - buy a solid carbon drill bit if you want to attempt drilling a clutch weight; they are extremely hard.