Tuned skidoo 850T clutching problem

[Rmk93]

I recently purchased a 2021 skidoo turbo I’m having a problem with the sled at higher elevation 5500+ft with a studder when quickly opening up the throttle wide open. The sled will peg 8100 (I know over revving) and studder to 73-7400 then back to 7900 or 8000 then pulls

Sled is tuned now with a 20hp ibex tune
Currently has ibackshift clutch kit installed.

I tried clicking down to pos 1 and adding pivot weight.

Before tune the sled had a 40mm pivot bolt with a 4mm bushing on pos 3
(I added the tune the sled before I ever rode it)
I tried adding a 7mm spacer, a 3mm and a 2mm on the pivot bolt and would still spike 8100 then quickly drop to 7800 or 7900. With the problem still occurring sometimes.

Is the clutch not loading fast enough and the sled thinks it is over revving and pulling the RPMs down. Is an adjustable set of ramps the solution?

 

[greenthumb]

I recently purchased a 2021 skidoo turbo I’m having a problem with the sled at higher elevation 5500+ft with a studder when quickly opening up the throttle wide open. The sled will peg 8100 (I know over revving) and studder to 73-7400 then back to 7900 or 8000 then pulls

Sled is tuned now with a 20hp ibex tune
Currently has ibackshift clutch kit installed.

I tried clicking down to pos 1 and adding pivot weight.

Before tune the sled had a 40mm pivot bolt with a 4mm bushing on pos 3
(I added the tune the sled before I ever rode it)
I tried adding a 7mm spacer, a 3mm and a 2mm on the pivot bolt and would still spike 8100 then quickly drop to 7800 or 7900. With the problem still occurring sometimes.

Is the clutch not loading fast enough and the sled thinks it is over revving and pulling the RPMs down. Is an adjustable set of ramps the solution?

A brief spike like that from a holeshot is typical on skidoos. That's not high enough to worry about. The factory tune doesn't limit engine speed until somewhere around 8500. Seems like the steady wot rpm's are pretty good.
Hard to say on the 'studder'. How many rides like this? Maybe cover the basics; fresh fuel, check the plugs and wires, etc. Unfortunately since you added the tune before riding it stock, you don't know if it was a pre-existing problem with the sled or a result of the tune. Perhaps reach out to ibex for suggestions.

 

[Rmk93]

A brief spike like that from a holeshot is typical on skidoos. That's not high enough to worry about. The factory tune doesn't limit engine speed until somewhere around 8500. Seems like the steady wot rpm's are pretty good.
Hard to say on the 'studder'. How many rides like this? Maybe cover the basics; fresh fuel, check the plugs and wires, etc. Unfortunately since you added the tune before riding it stock, you don't know if it was a pre-existing problem with the sled or a result of the tune. Perhaps reach out to ibex for suggestions.

It was the first ride, the original owner put this clutch kit in brand new and rode it for 2000km. I thought it I could make up for the extra 20hp with pivot weight, that is not the case, pivot weight does not seem to be helping bring down rpm’s at all, even when it settles down, a friend was riding with me with the same snowmobile and same fuel but with a 30hp ibex tune, his seems to run a lot better.

I have pulled plugs and will replace, they do not look great, im also going to add a set of slp adjustable weights, where i can add weight to the ramp itself instead of the pivot bolt.

Maybe I have to swap primary springs, I have the paperwork for the ibackshift clutch kit but it does not show what springs came with the kit. I can see a all red primary spring and the helix is marked NC-D6

 

[jcjc1]

pain in the ass but i'd put everything else back to stock and ride it to see if it's related or not to the clutch/tune.
good luck.

 

[Eternalwinter]

It was the first ride, the original owner put this clutch kit in brand new and rode it for 2000km. I thought it I could make up for the extra 20hp with pivot weight, that is not the case, pivot weight does not seem to be helping bring down rpm’s at all, even when it settles down, a friend was riding with me with the same snowmobile and same fuel but with a 30hp ibex tune, his seems to run a lot better.

I have pulled plugs and will replace, they do not look great, im also going to add a set of slp adjustable weights, where i can add weight to the ramp itself instead of the pivot bolt.

Maybe I have to swap primary springs, I have the paperwork for the ibackshift clutch kit but it does not show what springs came with the kit. I can see a all red primary spring and the helix is marked NC-D6

Email Joe at ibackshift. He is great about helping to get things dialed in. Very helpful. He did just tell guy I ride with, after upping his turn turbo from stock, that if he had a bog/studder to change the primary spring. Send him an email or try and call her should be able to help you out.

 

[Rmk93]

I did get ahold of Joe, he also suggested to change primary back to stock. I ended up putting a stock Gen 5 spring in 150-250 but that didn’t seem to help, I think it was a fuel filter problem, I changed the filter and seems to be better now.

 

[Caper11]

I suggest reflashing the sled. Thats not a clutch problem. Ibex tunes are problematic.


Sent from my iPhone using Tapatalk

 

[Shredder]

a friend was riding with me with the same snowmobile and same fuel but with a 30hp ibex tune, his seems to run a lot better.

The biggest issue isn't the extra 10 hp; it's the rest of the equation. You can find out and compare spring rates and gearing. But the big factor is that nobody will tell you what angles are in any kind of custom cut helix. If you have a 150/350 primary; with the stock pivot/ramp set up; and the stock straight 40 helix/secondary spring I would put all that in. Then just bring along some pivot washers and maybe a couple longer bolts. At least that will get you a base set up. But after all that is in I would flash it back to stock and get the RPM's dialed in. Then change nothing after putting in the tune and see how it reacts. Good luck.

 

[ctd]

The biggest issue isn't the extra 10 hp; it's the rest of the equation. You can find out and compare spring rates and gearing. But the big factor is that nobody will tell you what angles are in any kind of custom cut helix. If you have a 150/350 primary; with the stock pivot/ramp set up; and the stock straight 40 helix/secondary spring I would put all that in. Then just bring along some pivot washers and maybe a couple longer bolts. At least that will get you a base set up. But after all that is in I would flash it back to stock and get the RPM's dialed in. Then change nothing after putting in the tune and see how it reacts. Good luck.

I'm not commenting on the tune.

Bathroom scale & ruler will give you spring rates. You should use that as a constant & measure. Spring rates are different new & set.

Felt pen & protractor will give you helix angles, no magic hocus pocus. Makes me crazy top super secrets angles.

The equation is difficult as in anything to improve upshift will oppose backshift & the other way. This is the magic.

 

[Teth-Air]

I did get ahold of Joe, he also suggested to change primary back to stock. I ended up putting a stock Gen 5 spring in 150-250 but that didn’t seem to help, I think it was a fuel filter problem, I changed the filter and seems to be better now.

My buddy had a few plugged filters on his Doo's and found the fuel pumps full of black gunk. It was never determined if it was from bad fuel or what.

 

[Shredder]

My buddy had a few plugged filters on his Doo's and found the fuel pumps full of black gunk. It was never determined if it was from bad fuel or what.

This seems to be an issue that is popping up all over the place lately; not an issue a guy expects to deal with on a new sled. When they are charging us over $2.00/L for premium "Bad Fuel" should not be an issue that we need to worry about either.