Secondary clutching question (rpm drop)

[stgdz]

Figure I would ask this hear as there seems to be a fair amount of experts here

I have a zuke 2013 800 procross that falls off at 90-95mph. Anything up to them is fine. But once it got to that range it loses power. I had rebuilt the secondary and didn't find anything out of the ordinary on inspection. I replace the ramps and the bushings on the cat secondary. New springs and weights in the primary.

Rpm up till then was about 8-8200 from what I recall.

This was a couple of years ago, when we had snow, on the lake. I can't find my pictures of the primary with the marker, but where should I start looking this year on this issue?

Is it all secondary related at that speed?

 

[1nc 2000]

Hyfax sticking. More wheels in rear skid to overcome heat and friction.
Ice scratchers...

 

[Turboflash]

I have "fixed" a number of these 800s for this same problem. Along with the seeming drop off in power, owners also say their belt and clutches get very hot (hot enough to sizzle spit on clutches) to the point of belt failure, lots of blown belts.
Sleds seem to "hit a wall."
Many dealers addressed the heat by adding vents. This did not fix the root cause of problem - which is, over-shifting. Meaning, the primary can shift more than secondary. If one holds it wot, the primary continues to try to shift up more, but secondary is all done and can't. So belt gets tighter and tighter, and all that tension creates tremendous heat. And, pulls engine RPM down. Sled won't accelerate any more.
I first noticed this phenomenon running an 800 with chain removed and watching the clutches. It was easy to see the secondary stop shifting but primary not done yet.
The cure is: machine the secondary spacer to allow secondary to shift as much as possible (use magic marker to mark it), run clutches as much as needed to prove belt is as deep into secondary as possible. Next address primary. It can still shift more than secondary.
Install 3, 1/4-20 bolts each with a lock nut, into spider to limit how far the clutch h can close up (which is at limit of what secondary can do). Problem solved.
Upon field testing sleds, the sleds pulled all the way out, belt and clutch heat waaay down, sleds had more top end, and all the lost RPM was back.
I fixed many of these sleds years ago and have heard from some of the owners since. They report no further issues, great belt life, no heat problems, and sled performance really well.
It's an Arctic Cat engineering design problem.

 

[stgdz]

Tflash

Is there a correlation between the marker stripe in the secondary and the spacer machining. I recall cat updating the spacer so I'm not sure what the OAL of the spacer should be.

In regards to the primary, where are the 1/4 bolts put in?

 

[Upstater57]

Belt heat was a big problem on my old modstock 1100 turbo. Venting in fresh air and blocking heat from the engine compartment lowered temps quite a bit. I went on to a TAPP clutch and a Pro 4 secondary once I tuned the sled to 300HP. Controlling the heat, make the belt offset perfect, and ensure the clutches fully shift out was the fix to belt and performance issues.

I love my 998 but I do miss the brute force of the 1100 from 20mph to 100mph. It was almost violent.

 

[Turboflash]

Tflash

Is there a correlation between the marker stripe in the secondary and the spacer machining. I recall cat updating the spacer so I'm not sure what the OAL of the spacer should be.

In regards to the primary, where are the 1/4 bolts put in?

Just machine spacer so the secondary can shift as far as possible. Make sure belt stays on angled sides of sheaves, but the inside of the belt can be slightly below that line (maybe about .030"). You might have to extend (machine) the angle of your helix (basically put a relief at bottom of angle). Otherwise, the rollers might get stopped because the length of angle of helix is too short.
You can install bolts (use 5/16" fine thread about 1-1/4" to 1-1/2" long) in cover so heads will contact spider just below slot where rollers are. Have a jam nut on each bolt (on outside) and cut a slot in end of bolt to facilitate use of screwdriver to adjust them. You want all 3 bolts to contact spider at same time.
Run sled (with chain removed) and watch secondary. At the point it stops shifting, you want to set the 3 primary bolts to not allow any more shift. You'll end up with belt about 1/4" below top of primary at full shift. Over time, keep an eye on adjustment bolts in primary. Over time, they will tend to create a flat spot where they hit the spider. Might have to tweak them a bit.
You'll be amazed at how sled runs once you're done. Faster than ever, and no hitting a wall, and cool belt temps.

 

[stgdz]

So this is what I'm seeing with just ditch railing. I haven't been able to open it up on the lake as conditions have been terrible. I marked the secondary at a few different spots and will check it tomorrow.

It's spinning about 8k from what I have seen. It has about 160 studs and a 1.25" track, so it's probably brining it down a bit. Again spring is stock cat as are weights.