Clutching issues / Bushings?

I dont think bad primary bushings would cause your problem, however the bushing in the secondary movable sheave would. If you can feel any wore/wallowed out spots on the hub the bushing rides on...that could be your problem.

You have a very hard primaryspring, i have a 145@2,5inch and 275@1,25 inch
Maybe it will help to loosen up that.
Today i bought a yellow/green one to try.

I chased this issue 2 years ago on my M8! Tried everything, Springs, Helix, Rollers and weights!! Turned out my motor mounts were shot. Fixed them and has been great with no issues. Hope this helps!

What's the mileage? Might just be time for new clutches.
You try dropping weight?

On the secondary clutch, the manual calls for .020 bushing wear between fixed and moveable. The wear on mine before they warrantied it was impressive and definitely affected how my sled performed. My sled would get the rpm but wouldn't hold it. Kept breaking rollers because I had a cutler silver cranked. Also had the SW 340 like you.

I couldn't find a guideline or spec in the manual for the primary but I'd imagine it might be about the same. I know you'd need special tools to take everything apart but it's the only way to find out.

A) put in a new spider while you've got it apart.
B) prepare to buy yourself a new clutch

If you think it's binding, you're probably right. Think of it this way: Your primary is pulling the belt from the secondary. Your secondary is under load, so the front facing half of the clutch is essentially cocked wider than the back when you're on the hammer. It does help that you've got the cover bushing helping the scenario out (unlike the secondary) but you can't rule it out.

Check that secondary too, it'll kill off your engine as it's doing the same getting cocked all day long. You could also add a shift assist... Either way, let us know what you do.

For this season, I got the secondary warrantied and bought a new primary. I had just over 5000miles so it was due. Went through three spiders and several rollers. Haven't broken anything since I changed the secondary.

Bought MDS weights, steve set me up for 86g. I dropped them to about 83. It's fine right now but I figure I could drop another gram to really keep my 7500 that my sled likes.

arcticat said:

Not trying to disagree with you, but isnt most of your rpm going to be controlled by the primary? and if the bushing is bad in the secondary wouldnt it just slip more?

Click to expand...

To a point, yes RPM is controlled by the primary. If the secondary is bound up it will load the primary and you will not pull the correct rpm. It would not slip more in the secondary. Inspect the bushing and hub it rides on in the secondary, make sure the aluminum hub the moveable rides on is not grooved/wallowed out. It would be helpfull to know the miles.

BTW...if the bushings in the primary are wore out the weights will still fly out. Not much will stop them from moving at 7500+ rpm.

I found that the stock rollers would bind up as I modified my sled and added weight and secondary pressure. If you are pulling Rs on the road, but not when loaded up, you aren't backshifting well enough. My bet is you pull Rs at first on the climb but as you dig in and the track speed starts to drop, the Rs drop right with it. The plastic rollers wear very fast and are a bigger source of binding than I ever predicted. Put some hard rollers in the secondary (I use rock rollers) and the back shift will improve. Ultimate fix? I went to a RKT secondary kit and never looked back. Pulls Rs all day and works very well. But, the rock rollers were added to the RKT kit after I realized the plastic ones were binding up (flat spots here and there). That really made the kit complete. If you pull the stock plastic rollers, you'll be surprised how loose and worn they get. If the primary is sticking, you'll get sudden RPM shifts...had that happen on another sled before. When you add the rock rollers, add another spacer and go to three...that will help the back shift as well. Rock rollers and a shot of WD40 every other ride and it shifts great.

hi-torque rollers also are a great choice. extremely durable rollers. had 4000 miles on my last set and no flat spots.

Did you figure this out? In my last post I should have clarified that the bound secondary may pull RPM for a while then drop off as the belt heats.