Ski Doo 850 Turbo Overreving....add clutch flyweight grams

o zone guy · Dec 4, 2020

The Kickass One said:
What in the world is that?

sometimes a guy can't always be kicking ass ... Gotta back shift from time da time !!! LMAO !!! That s the facTs JacK bill MurraY would be proud !!! wooT !! wooT !!! Let's get this thread back on track ... ibackshift.com... I am backSHiFT... WE are backSHiFT... THiS is backSHiFT... snow n mud... thanks for this chat room ... Now leTs RamP iT uP Period... beeP !! beeP !!!

fredw · Dec 5, 2020

Buddy called about the same issue this week joe, I will be sending him your way, said he’s hitting rev limiter pretty often, and 8200-8400 rpms seen and only 60 percent break in removed.. dealer said to add heavier bolts or washers, I’m not really up on pdrive... but would think it should be set so you have calibration room to go up or down on clickers to give some room on different riding conditions.. would a inn proper skid calibration also contribute to this, he’s a bigger guy

would think brp could do a better job than this for that much $$ spent.. he will be calling soon

rknight111 · Dec 5, 2020

I ordered a kit from dynamo joe Thursday and I recieved today. Very impressed with speed of shipping and quality of parts in box

oler1234 · Dec 7, 2020

so what is the ideal peak rpm for these turbo sleds? is it still 7900rpm?

seen some dyno graphs indicating 77-7800rpm was peak power.

Dynamo^Joe · Dec 8, 2020

Im not getting on your case. Please, Im just making a point. Never mind asking, just go do it. These kind of questions just dont bear any fruit.

Go ahead and clutch your bikeman mufflered, bikeman tuned turbo sled for 7700 rpms out in the snow, in the actual environment you run at. You'll be the first one to have personal firsthand knowledge to answer your own post. Dont ask anyone, just go out there and do it yourself and see the results.

And...never mind the bikeman s4it, just go do it stock, run stock at 7700 rpms out there and see how far you get.

....And then come back and tell what happened in your testing.

My fellow S-n-M brothers. So it was heard that etc etc 7700 and etc etc and i tried my heart out to run it there and so-and-so happened.

...

snowseeker · Dec 8, 2020

I spent a few days working with a shop on the clutching. You can rev it at 7900 rpm or 7400 rpm and make more vehicle speed at 7400 if your not slipping the belt then at 7900 and your slipping the belt . It doesn't matter what RPM if the belt is slipping.
We used a Garmin GPS that tracked actual vehicle speed up the hill and not just track speed and we found that the sled likes to be loaded and we got the fastest speed with rpm between 7400-7600. Also when we chalked the primary we were fully clutched out and there was no slipping of the belt.
We had 2 factory turbo sleds to compare apples to apples. One rider and 3 passes each time so sleds were warm and there was no different rider or weight factors.

1709 · Dec 8, 2020

snowseeker said:
I spent a few days working with a shop on the clutching. You can rev it at 7900 rpm or 7400 rpm and make more vehicle speed at 7400 if your not slipping the belt then at 7900 and your slipping the belt . It doesn't matter what RPM if the belt is slipping.
We used a Garmin GPS that tracked actual vehicle speed up the hill and not just track speed and we found that the sled likes to be loaded and we got the fastest speed with rpm between 7400-7600. Also when we chalked the primary we were fully clutched out and there was no slipping of the belt.
We had 2 factory turbo sleds to compare apples to apples. One rider and 3 passes each time so sleds were warm and there was no different rider or weight factors.

How did you tell if the belt was slipping? did you take belt temps? how much weight did you add to get the rpms down to 7400?
yes the engine has to be loaded for what ever rpms you have it clutched for. if you load the engine and spin 7900 you will go faster then loaded at 7400. with very little belt slipping. (there is always slippage)
was the pipe hot or cold when you tested? cold pipe will make power at lower rpms, but as pipe temp rises so does peak power rpms.
So if you were clutched better and loaded the engine more at 7400 then 7900 then yes you would go faster.

snowseeker · Dec 8, 2020

1709 said:
How did you tell if the belt was slipping? did you take belt temps? how much weight did you add to get the rpms down to 7400?
yes the engine has to be loaded for what ever rpms you have it clutched for. if you load the engine and spin 7900 you will go faster then loaded at 7400. with very little belt slipping. (there is always slippage)
was the pipe hot or cold when you tested? cold pipe will make power at lower rpms, but as pipe temp rises so does peak power rpms.
So if you were clutched better and loaded the engine more at 7400 then 7900 then yes you would go faster.

We had a temp gun with us when we did the clutching. We marked down the clutch heat each time to compare results. Both sleds were warmed up and 3 passes were made with each set up change so we were comparing the same every time.
We ran 83grams of weight and clutches were cool. We took out 1 gram of weight gained 200 rpm and was slower and clutch heat was a lot hotter.
I have had 4 aftermarket turbos built by mountain magic and can say this clutching on the factory turbo is so much more finicky then the other ones I have had running 5lbs or 8lbs of boost.

mur190 · Dec 9, 2020

Darren are you running a P-Drive or MM P-85/Team set up?

snowseeker said:
We had a temp gun with us when we did the clutching. We marked down the clutch heat each time to compare results. Both sleds were warmed up and 3 passes were made with each set up change so we were comparing the same every time.
We ran 83grams of weight and clutches were cool. We took out 1 gram of weight gained 200 rpm and was slower and clutch heat was a lot hotter.
I have had 4 aftermarket turbos built by mountain magic and can say this clutching on the factory turbo is so much more finicky then the other ones I have had running 5lbs or 8lbs of boost.

snowseeker · Dec 9, 2020

mur190 said:
Darren are you running a P-Drive or MM P-85/Team set up?

We ran the skidoo stock Clutches.

skegpro · Dec 11, 2020

So do we have a general consensus on how much weight needs to added yet?

Is everyone leaving clickers on 1 then adjusting? Or moving to 3 and then adding weight?

oler1234 · Dec 11, 2020

175 track, clicker 1, 8100rpm.

gonna go the 20.5 heavier clutch arm route.

rknight111 · Dec 11, 2020

I was going to leave on clicker 1 and add the longer bolts and a 1 gram washer. But decided to install Dynamo Joes proven clutch kit instead of screwing around with clutching that should of been right from purchasing a new snowmobile in the first place. Next time I'm in the mountains I'll comment on the new clutching.

hardcorex · Dec 11, 2020

Ron, you already ran yours stock , what was it pulling for rpm at elevation?

rknight111 · Dec 11, 2020

hardcorex said:
Ron, you already ran yours stock , what was it pulling for rpm at elevation?

Cant see the gauges to see what rpm. It just keeps hitting rev limiter, then backfiring to release all the excess fuel. Dealer found one of the spark plugs wasn't indexed. And added weight to clutch and they want to see this run before I put the kit in.

Cableguy · Dec 11, 2020

do u guys have a total weight of ramp with bolt/pins installed

skegpro · Dec 11, 2020

rknight111 said:
Cant see the gauges to see what rpm. It just keeps hitting rev limiter, then backfiring to release all the excess fuel. Dealer found one of the spark plugs wasn't indexed. And added weight to clutch and they want to see this run before I put the kit in.

What rpm is the rev limiter?

How much weight did they add?

fredw · Dec 11, 2020

your findings seam to compare to my findings so far with the pdrive..it also never seamed to have the bottom end pull my other boosted tra kits have driven same day...also found some very hi temps on p drive primary and was also thinking belt slip.. i did find that i was able to add 5 degrees more helix and still keep rpm consistent and temps actually dropped with good backshift.. this pdrive is looking a a hp robber if not calibrated correctly... hope for next ride to swap out tra and pdrive and compare there abilities and disabilities

snowseeker said:
We had a temp gun with us when we did the clutching. We marked down the clutch heat each time to compare results. Both sleds were warmed up and 3 passes were made with each set up change so we were comparing the same every time.
We ran 83grams of weight and clutches were cool. We took out 1 gram of weight gained 200 rpm and was slower and clutch heat was a lot hotter.
I have had 4 aftermarket turbos built by mountain magic and can say this clutching on the factory turbo is so much more finicky then the other ones I have had running 5lbs or 8lbs of boost.

Catman10 · Dec 12, 2020

Does anyone know what the stock primary ramps are in the 2021 turbo's, 965?

Catman10 · Dec 12, 2020

My 175 is revving at 8000 rpm on clicker 1, I geared it up last trip and moved it to clicker 3 which gained me 3 kms more track speed and ran at 8100, now to start clutching this beast, I have all of the information except ramp size which I will find out this week when my doo tools show up, such a pain in the ass to work on these clutches, I want my Yammie back!

Ski Doo 850 Turbo Overreving....add clutch flyweight grams

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