Kinda new to clutching. Could use some guidance

[polemite.productions]

right now i am in the process of tuning my m7/8bb clutching to reach the 8100rpm mark, up from 7800.

i have a basic understanding of how my sled's clutch components work, but my experience with clutch work and maintenance (up till 2 days ago) has been limited to installing an rkt torsional mod, and changing my belt.

so i need to gain 300rpm. i'm told that i should increase primary spring pressure, and decrease primary weights. i started with changing the spring in the primary. i went with the orange/black which the shop guy tells me is the same spring rate as the black/orange in the new sleds, but it doesn't snap. the original yellow/white looks pretty sacked out. (like i said, i never did much clutch maintenance in the past)
on the mountain i was getting engagement at around 4000rpm, which was definitely up, and it felt like much smoother acceleration. on a nice long hillclimb at wide open throttle i was seeing that 7800rpm, but then after about 200 yrds (and slightly steeper pitch) i saw the rpm creep up to 8000 rpm, and hold there for the rest of the climb (about another 200 yrds).

so now i'm wondering, why did it take so long to hit 8000rpm? is this typical?,
do i need to change more parts?,
could this be a result of some other worn out part that i should be looking for? (ie. primary/secondary rollers).
can belt tension play in as a factor? mine was a little on the tight side, but i didn't have an allen key with me to loosen the bolt and play with the tenison.

i also read up on my rkt torsional, and apparently by adding more preload spring pressure, the motor should wind up quicker and give me a little rpm at the top. is this the answer?

and if anyone would like to elaborate, i would love to hear about any common problems that do occur, and what symptoms to watch for to identify them.
sorry about the long post!

 

[Frostbite]

What's your target shift speed (top RPM). So you are 7,800 to 8,000 now. Do you have twin pipes? That sounds pretty high.

It sounds like you are close?

You could back off the tension a hair on your secondary, you'd loose a few RPMs up top but also lose some of that wicked backshift you have going now. Also as you say, you can tighten it for a few more RPM but, you should tune your shift speed with the primary and just use the secondary to tweak RPM a bit for daily snow changes.

Tell us more........................

 

[polemite.productions]

it kinda sounds like you didn't read my post too thoroughly. just to make things clear, the 800bb is supposed to make peak hp at 8000-8150rpm, and i am running a speedwerx 925 single. so that is why my target is up around the 8k mark. and to simplify my quesitons, why am i not reaching 8k rpm untill after i've been pulling for so long? is this normal, is it my setup, or should i be looking for worn out parts?

 

[slomo]

i run 70g wieghts,orange/white primary and white secondary with a shift assist,recommended by tatorsalad and isharted who have run these kits for a while and gave me great info i'm pulling 47-55mph speeds on a big hill with this set up with a 42/36 dalton helix@8100 rpm.it pulls hard

 

[polemite.productions]

thanks slomo, thats awesome. how quickly do you achieve 8100? is it right away, or does it slowly climb up there like mine is right now?

 

[dchgos69]

Any time I see this kind of change in RPM during a pull, I start looking for worn parts.

Belt is first suspect. Then deflection, alignment, side-clearance.

Next, check primary weight bushings. Easy and cheap to replace. Then more involved look into the primary rollers. Should be NO play in them. I think that the spider with roller kit is a better deal than buying rollers separately. Maybe even a whole primary is better than rebuilding depending on the dealer/deal you can find. Primary movable sheave bushing is not replaceable according to the 'fiche. The cover bushing is, $6.

Then secondary, rollers, bushings, and helix for bumps/notch/ripples.

Also check on the primary weights for any ripples/notch/gouge. I have smoothed them out with sandpaper on a hard flat surface, but they tend to wear faster and notch deeper the next time. So it may be best to buy a new set if that is the case.

You also just put in the new spring, check to see if it is binding. Any rubbed paint?

DCH

 

[polemite.productions]

just got a chance to go out in the garage and check a few things.

yes, the primary spring is getting some rubbing.

yes, there is some play in the primary rollers.

and the rollers that are in contact with the helix at idle are looking worn. maybe even just beginning to develop flat spots.

looks like i have some work to do, and some money to spend.... damn.

 

[slomo]

thanks slomo, thats awesome. how quickly do you achieve 8100? is it right away, or does it slowly climb up there like mine is right now?

hits around 8 and climbs the last 100

 

[akjimmyb]

What elevation are you running? I have a RKT 800 on my M7 with speedwerx single and had to go up to 77 gram weights, with orange white spring. Enguagements just above 4000. I'm running RKT secondary kit and run it in the 4th notch on the tight side, (arctic cat sno pro green). I pull 8100 - 8200 in a climb, with good track speed. I get a little overrev when drag racing, say on a lake, but set up is great on the hill. I should tell I'm running sea level to 4000'. Also running RKT 38/36 helix.

 

[polemite.productions]

almost all of my riding is done between 6000 and 7000 feet, give or take 500ft on either end depending on which area we are riding on a particular day.

my rkt helix is the 34 and i use the red/white spring. it is currently set on the middle hole.

i just pulled one of my primary weights and it has 703-68 stamped on it. so i'm assuming that it is a 68gr weight.

when i was doing a flat pull across the lake, i was actually seeing less rpm (7600 tops) then when i was pulling a climb. would this suggest that my secondary is backshifting lots, and this is why i see the 8k rpm as the climb got steeper and deeper?

 

[IShartd]

almost all of my riding is done between 6000 and 7000 feet, give or take 500ft on either end depending on which area we are riding on a particular day.

my rkt helix is the 34 and i use the red/white spring. it is currently set on the middle hole.

i just pulled one of my primary weights and it has 703-68 stamped on it. so i'm assuming that it is a 68gr weight.

when i was doing a flat pull across the lake, i was actually seeing less rpm (7600 tops) then when i was pulling a climb. would this suggest that my secondary is backshifting lots, and this is why i see the 8k rpm as the climb got steeper and deeper?

With that set up you should be able to easily pull 70g weights at your Elev and get 8100rpm all day long. What domes are you running? I run 72g weights from 7500' - 9500' with the exact same clutching otherwise and get 8150rpm no problem.

Make sure your secondary rollers have no flat spots and that the screws holding your torsional setup to the sheaves are tight. Move your torsional adjustment to the left 1-2 places, see what you get. You shouldnt have any play in your primary rollers and if they have flat spots your pretty much all done, that would be time for a new primary. the orange/white spring works good, and its probably loosing paint because of constant compression, I wouldnt really worry about that.

 

[polemite.productions]

i've got the 13.5:1 domes. thanks for the advice. i'm gonna pull that secondary off soon and check those screws as well.

anyone ever successfully replace their spider? from the little bit of searching i've done, it sounds like a real beeotch to get it off. am i better off bringing it in to the shop?

 

[IShartd]

Your gonna have to take it to the shop, unless you have the tool. The way AC has set up their price structure for this part and other primary related parts, your better off just buying the whole thing, check Ebay or the swap meet, I payed 160 for a brand new one off ebay last year.