Clutch/belt temps

[Joe ltx-le]

Wondering if a 35/33 might be the ticket

Anything is worth a try. My theory was we need more low end revs but the 33/35 might help load up the engine , what I found was this helix has amazing mid range but I loose some revs on the top end.

I'm holding off on making my dalton order until I decide on two new helixes to test. Straight 33 and one more.

 

[**sj**]

Anything is worth a try. My theory was we need more low end revs but the 33/35 might help load up the engine , what I found was this helix has amazing mid range but I loose some revs on the top end.

I'm holding off on making my dalton order until I decide on two new helixes to test. Straight 33 and one more.

and the other?

 

[jlinstruth]

Would like to share info, to keep from having to buy garage full of parts, In theory if stock clutching is good, then when boost is added more weight in primary will be required or softer spring, and also more belt squeeze in secondary will be required, via spring or helix.

 

[KnappAttack]

Would like to share info, to keep from having to buy garage full of parts, In theory if stock clutching is good, then when boost is added more weight in primary will be required or softer spring, and also more belt squeeze in secondary will be required, via spring or helix.

More weight in primary yes. More belt squeeze in secondary no. The only time you'd want more belt squeeze in the secondary if if you have a belt that is slipping. Efficiency goes way down and belt/clutch heat goes up if all you are squeezing the secondary and it is not needed.

Clutching is a balancing act to run right in that small sweet spot of not slipping and not over squeezing the belt. Any slipping you have heat, and you will also have heat if the clutches have too much squeeze.

Sometimes you'll need quicker shift out in the secondary, not less. More squeeze in the secondary means slowing the shift. So many factors come into play.

The reason some are going less and reverse helix is because they ramp the boost in over RPM. Quicker spooling tunes don't need reverse helix's, quite the opposite actually. They need more helix to shift them quicker and sooner, also its gearing, traction and belt dependent.

 

[Doc Harley]

Is there a reasonable amount of belt slip? 8jp belt

 

[KnappAttack]

Is there a reasonable amount of belt slip? 8jp belt

View attachment 135122

You can have perfect clutching on a four-stroke and have that. Generally the belt will put hard marks on the clutches from letting off. Black marks do not always mean its slipping on the upshift. Keep in mind when you let off with a torsion secondary, only the spring will hold the sheave against the belt. The helix basically releases all pressure from the belt, until you get back into the throttle and it applies pressure to the belt again.

I wouldn't get nervous about some streaking as you have here really. Stock I assume?

 

[Doc Harley]

Yes, Mike all stock. I didn't want it to grenade at speed.

 

[Joe ltx-le]

and the other?

Still undecided.

 

[theewarrior]

So does anyone know a good average clutch temperature

 

[Joe ltx-le]

So does anyone know a good average clutch temperature

No, but I always use my hand. I could always tell when there is a heat problem. If you can lay your hand on the clutch face and leave it there after a big run its always been my opinion that the clutches aren't running hot.

Buddy's 850 I could barely touch the primary it was so hot

 

[ClutchMaster]

You can have perfect clutching on a four-stroke and have that. Generally the belt will put hard marks on the clutches from letting off. Black marks do not always mean its slipping on the upshift. Keep in mind when you let off with a torsion secondary, only the spring will hold the sheave against the belt. The helix basically releases all pressure from the belt, until you get back into the throttle and it applies pressure to the belt again.

I wouldn't get nervous about some streaking as you have here really. Stock I assume?

Huummmm

 

[snowbeast]

Sorry no tune in this sled, just dial a boost so peak rpms 8800, but there's more than adequate power down to 8200, at least according to dyno sheets

In fact,if you tune up the hp from stock,to 240,that is same as any ones 240 tune,you still have extra hp to mess up your stock clutching,that came in stock sled correct? Just because this tunes/dial a boost max rpms are 8800 ,means little compared to stock 8700,the tuned sled needs different clutch set up,because it hits harder all throughout the rpm range,so it will increase belt,and clutch temps because of the HP added. But those clutch and belt temps don't sound outrageous at all,heck our procross turbos would have belt temps near 300 degrees,and clutches were all around 200 if I remember correctly. Are you blowing belts at all?

 

[yammitrip1]

If you actually ride your snowmobile. It's always going to have a warm clutch, mountain riders almost never have a cool clutch unless there geared to go 35 mph

 

[jlinstruth]

No belts blown except when dragging on grass this fall, which was due to spinning off line, then grabbing bite, and also running belts to loose. I was following manual for belt tension, have a great dealer (Excell motorsports) that threw on a threaded adjuster and showed me a better way to check tension, haven't blown belt since. So sounds like 150 degree temps aren't to bad from what I am seeing, just a tad higher than used to with skidoo. I assume gearing is playing big part as the increased power is trying to shift all way out regardless of conditions which with heavy snow has the load working against driven clutch producing heat. So I am thinking a helix in neighborhood of 37/33 would indeed maybe help to slow shift down at end.

 

[snowbeast]

No belts blown except when dragging on grass this fall, which was due to spinning off line, then grabbing bite, and also running belts to loose. I was following manual for belt tension, have a great dealer (Excell motorsports) that threw on a threaded adjuster and showed me a better way to check tension, haven't blown belt since. So sounds like 150 degree temps aren't to bad from what I am seeing, just a tad higher than used to with skidoo. I assume gearing is playing big part as the increased power is trying to shift all way out regardless of conditions which with heavy snow has the load working against driven clutch producing heat. So I am thinking a helix in neighborhood of 37/33 would indeed maybe help to slow shift down at end.

That might not be a bad choice for the turned up winder,like ours,i was thinking of 38/35 to matain same top rpms and load motor faster. My straight 38 last year grunted off line better than stock 35 does right now,need more distance to see rpms,how they work out,to say,but once I get up north and run it,i can tinker some.