Looking at aftermarket clutching for M8... Opinions wanted

[Bails]

Just like the title says, I am looking at upgrading my clutching on my 2007 M8 (1700 miles). I'm looking at trying to get some better bottom end, without sacrificing top end too much. I looked into the Rk Tek diamond drive clutch kit, and it sounds like its what I need, but I'm looking for some opinions on this kit or other kits out there.

I live in Saskatchewan, and just swap out my weights when heading west. Is this still possible to do, or are there other options? Basically I'm a clutching rookie and I am looking for advice.

 

[css]

Call Steve at MDS 1-509-899-0605, I talked to him today and he was a big help and has a set up that allows you to leave the same weights in and just change primary spring. I cant wait to try it.

 

[0neoldfart]

Call Steve at MDS 1-509-899-0605, I talked to him today and he was a big help and has a set up that allows you to leave the same weights in and just change primary spring. I cant wait to try it.[/QUOT
You will need a set of ajustable weights, whether you use cutler, MDS, or daltons. I do not recommend changing the primary spring - I suspect the vendor above is using a higher finish rate for the mountains, which will make it reach peak rpm, but will not be ideally clutched. My recommendation is this: Purchase a torsional secondary kit, load as much weight as possible into the flyweights that will allow it to upshift and backshift properly and hold rpm. Do NOT fall into the trap of chasing a certain RPM, as factory tachometers can be out +/- 250 RPM. Clutch by "feel" and you will be a much happier sledder. Also very important to make sure the clutches are clean and in good working order, and start with a new belt. If you take a bit of time, you will have a clutching system that works for YOU, as opposed to buying a generic "kit" which may or may not work as well.

 

[HiLlClImB911]

running cpc 38* with orange spring in sec, cpc adjustable in primary with stock tia yel/white on my m1000, got nothing but good to say about cpc parts and their service and I know its not a M8 like your title.

 

[sledhead800]

Just like the title says, I am looking at upgrading my clutching on my 2007 M8 (1700 miles). I'm looking at trying to get some better bottom end, without sacrificing top end too much. I looked into the Rk Tek diamond drive clutch kit, and it sounds like its what I need, but I'm looking for some opinions on this kit or other kits out there.

I live in Saskatchewan, and just swap out my weights when heading west. Is this still possible to do, or are there other options? Basically I'm a clutching rookie and I am looking for advice.

I run a 42/36 helix, with the cpc adjustable sec, purple white cpc spring in primary, orange spring in sec also all cpc stuff, works very good, This is on a 2010 m8 with a few mods

 

[Bails]

Anybody have any feed back on the Rk Tek Kit? thanks to those who have given advice on other products!

 

[Slamnek]

I bought my 09 with the RK Tek helix (42/36 i think) with a green spring that i think is worn out because i am using 68g weights for the mountians and i'm not over reving down low. Up high i am hitting 8000 but then it drops off a bit when i should be holding 8100 with the RKT head. The sled really rips but I think there is more to be had.

 

[0neoldfart]

I bought my 09 with the RK Tek helix (42/36 i think) with a green spring that i think is worn out because i am using 68g weights for the mountians and i'm not over reving down low. Up high i am hitting 8000 but then it drops off a bit when i should be holding 8100 with the RKT head. The sled really rips but I think there is more to be had.

Helix is a bit too steep. I would run a 40-34 or 38-34 for your application. Ideally you don't want more then 20# sheave opening pressure with a torsional secondary, and extra pressure will just create belt heat and shorten life. My wife's M8 with a 2.5"x162 track has 69g weights(adjustable), yel/white primary spring, a 38/34 RKT helix, and green spring set @ 20 lbs force. It holds RPM at elevation even on long climbs, but have to watch RPM on trail up or down.

 

[Slamnek]

Helix is a bit too steep. I would run a 40-34 or 38-34 for your application. Ideally you don't want more then 20# sheave opening pressure with a torsional secondary, and extra pressure will just create belt heat and shorten life. My wife's M8 with a 2.5"x162 track has 69g weights(adjustable), yel/white primary spring, a 38/34 RKT helix, and green spring set @ 20 lbs force. It holds RPM at elevation even on long climbs, but have to watch RPM on trail up or down.

How do you know it's set at 20lbs? I am very new to these clutchs and i know the RKT helix is adjustable. what setting is your wifes clutch on? I think mine is on the 3rd screw hole going from left to right. i am going to go check what my clutch is set on and post. I really like the machine but i'm sure it needs some fine tuning as well as new springs.

I am using a 38/36p helix

 

[0neoldfart]

I made a plate that can grab the rear secondary half, and use a spring scale on the outer diameter of the clutch (a fishing scale works good for this). As far as setting, I think it is on the second hole. A steeper finish on the helix will require more spring pressure to keep rpm, but track speed will suffer somewhat (lower gear ratio). Hope this helps.

 

[Stockorwalk]

Go to snowest forum they've got an exellent thread on there all about the basics of clutching , how everything works,what adjustments affect what and so on. I found it very informative.

 

[twostrokesrule]

A steeper finish on the helix will require more spring pressure to keep rpm, but track speed will suffer somewhat (lower gear ratio). Hope this helps.[/QUOTE]

I tried an RKT kit with the 38* helix that Kelsey recommended on my 2010 M8 but found that acceleration (upshift?) wasn't great. I barely was able to outrun my buddy's clapped out XRS800 Doo with 120lbs compression! But it did backshift great and always held perfect rpm at 8100 using 68gram cat weights. If I used a shallower finish like 34* would that have got me better upshift and trackspeed? Also I got the helix wearing a weird hole in itself. I've emailed Kelsey with pix but have never gotten a reply to date..... 'Old fart', you really believe in the torsional kit? What does Linderman recommend?

This past season I went to a Terra Alps compression kit to give that a try... and although it seemed to pull harder throught the rpm, I couldn't get it to pull past 8000. Generally it would stay in the 7800 range. That was using the belly buster 70g weights that Ted sells with his secondary helix. After a season of low rpm, i ended up putting in the 130-340 spring in the primary, and then i could get 8000 and even OCCASIONALLY hit up to 8200, but i can't say i'm impressed with this secondary setup either. Biggest problem on this setup was belt slippage when you first get on the gas out of the hole. It would often hit 8300, then once you backed off and then got back on it, it would drop down to about 7300 and you'd hardly be accelerating. Forget trying to climb any hill at that rpm. That caused a lot of stucks this year.

I don't really know where to go from here. I'm thinking about either going back to a stock compression setup or possibly trying the 38/34 that 'old fart' suggests... Or talk to Linderman. He seems to be the guy who really knows cats... Anyone else have any suggestions? I should also mention that I have a new primary and just picked up a 38/36 compression helix from Racinstation with a speedworks secondary spring

 

[Thunder101]

Formula X-1.

 

[0neoldfart]

A steeper finish on the helix will require more spring pressure to keep rpm, but track speed will suffer somewhat (lower gear ratio). Hope this helps.

I tried an RKT kit with the 38* helix that Kelsey recommended on my 2010 M8 but found that acceleration (upshift?) wasn't great. I barely was able to outrun my buddy's clapped out XRS800 Doo with 120lbs compression! But it did backshift great and always held perfect rpm at 8100 using 68gram cat weights. If I used a shallower finish like 34* would that have got me better upshift and trackspeed? Also I got the helix wearing a weird hole in itself. I've emailed Kelsey with pix but have never gotten a reply to date..... 'Old fart', you really believe in the torsional kit? What does Linderman recommend?

This past season I went to a Terra Alps compression kit to give that a try... and although it seemed to pull harder throught the rpm, I couldn't get it to pull past 8000. Generally it would stay in the 7800 range. That was using the belly buster 70g weights that Ted sells with his secondary helix. After a season of low rpm, i ended up putting in the 130-340 spring in the primary, and then i could get 8000 and even OCCASIONALLY hit up to 8200, but i can't say i'm impressed with this secondary setup either. Biggest problem on this setup was belt slippage when you first get on the gas out of the hole. It would often hit 8300, then once you backed off and then got back on it, it would drop down to about 7300 and you'd hardly be accelerating. Forget trying to climb any hill at that rpm. That caused a lot of stucks this year.

I don't really know where to go from here. I'm thinking about either going back to a stock compression setup or possibly trying the 38/34 that 'old fart' suggests... Or talk to Linderman. He seems to be the guy who really knows cats... Anyone else have any suggestions? I should also mention that I have a new primary and just picked up a 38/36 compression helix from Racinstation with a speedworks secondary spring[/QUOTE]
PM me your complete setup, rider weight with gear, any mods to sled, and usual riding elevation - will try to help you out.

 

[twostrokesrule]

PM me your complete setup, rider weight with gear, any mods to sled, and usual riding elevation - will try to help you out.

PM SENT