153-174 gearing and clutching?

[smithereenpsycho]

Just swapped my 2008 Nytro to a CE 174x16x2.5 from stock 153, the only performace mod I've done so far has been a Hindle slip on exhaust. And as I had figured, she don't quite turn on like she used to! So turbo aside(planning on saving for one next season) I want to get atleast a bit more power to the track for climbing without spending a poo-load... any suggestions on chaincase gearing? 19/40 or 18/40? what are the best clutching options that will have the ability to adjust once I swap to a turbo next year?

 

[tapex_07]

18/40 gearing for sure. As far as clutching goes, get the gearing in and let us know what rpm its shifting at. Thatll help with how to set it up.

 

[smithereenpsycho]

Switched over to 18/40 and it's doing much better on short pulls, but on longer hills it bogs out and I have to let off entirely then grip it again to pick it back up but it will bog out again after about 100 feet. Once in 10 pulls at a hill it shifts good and hauls #*$&@ but even when it's on a good run if it hits a bump it will bog again.

 

[tapex_07]

How old are the clutch springs? maybe one is broke or sagged out. The rollers could need replacing..

 

[kilometers]

I changed my gearing to 18 40 straight outta the box a Mtn sled dosnt need to go that fast Down A trail. I have no mods done to my sled they aregeared way to highDefintly helps in wet heavy snow. And for weeling over creeks etc easier on the belt

Sounds like your sled isn't back shifting when loaded up. Might e able to adjust secondary spring tension so it back shifts quicker

 

[smithereenpsycho]

I bought the sled used at 1600 kms and it is at 3000km now. I haven't replaced anything in the clutches since I've owned it and don't know about the previous owner, lets just assume it is all stock.... It's got a purple spring in the secondary, I tightened it up as tight as it would go, from what would be 7 up to 9... next ride is on the weekend so i'll see how it goes then re post results.

 

[..SNAKEBIT..]

I would check your weights and what rivets are in
I have the stock weight with no rivets, stk spring
sec: 39' helix white spring
running 18/40 gear, vector header w/undertunnel
162x16x2.5

 

[smithereenpsycho]

So after a short test run, it seems to be doing better with the tighter secondary spring buuut it is over revving when I punch the throttle while going slow in powder, it's not bad on hardpack but on hills with pow I need to slowly get into the throttle or it just feels like it is slipping and hits about 8900rpm.


I'm going to pull my primary next week to see what spring and weights it has...

 

[smithereenpsycho]

Here is my full setup specs...

Elevation - between 4000 and 6000 feet, riding mountain only, 200lb rider.

Sled Mods - Hindle slip on exhaust, 174x16x2.5 track(was 153), 8" wheels, 18/40 gears.

Primary - Green-White-Green, 8FS Arms, 2x13.3mm Steel Rivets with holes on the inner and middle positions and a 17.2mm Solid Steel in the outer position The complete weight of each arm is 75.7 Grams.

Secondary - Pink spring, well pretty sure it's pink, It kinda looks purple... As a guy they look the same, does yamaha make a purple secondary spring? there wasn't one in the Aaen Handbook. and now have the spring in the 7 position.

When I pin it the bounces off 8900 as it did before then drops back to 7400 and slowly climbs up from there but still can't hold it on a hill even once it gets up to speed, it won't bring the RPM's over 8100...

If ANYONE has any suggestions please throw them my way

 

[HYFLYR]

If your bouncing off the rev then backing down you want more weight in the heel and less weight in the tip. I would try loading up the heel and mid and go to a lighter tip weight, that will slow down your initial shift and maintain a peak rpm a little better. Also a yamaha white spring for the secondary wound to 90 would be where I would start to back shift that size of a track. It's stuffer than the pink.

 

[Jabber]

I just changed the clutch setup in my buddys 09 nitro running a 162 track. I put a 19 tooth top gear in cause I had one kicking around. the gearing is now a 19/40. 8fs00 weights with a 17.3mill steel rivet in the heel hole, mid and outer hole are empty. g/w/g primary spring. pink secondary, not sure what it is wrapped to as I didnt touch what was there. probably the stock setting. 39 degree helix. We ride 4000-6500 feet and the powder snow is dry and light, not like the coastal powder.

Today in 3 feet of virgin powder he was running at 8900 rpm. on the trail and lake at 5800 feet he hits the rev limiter. clutched for the powder riding, NOT FOR THE HARD PACKED TRAILS.

Sound like you will run a similar set up. keep the 18/40 gear set and start by removing the rivet in the outer hole. dont make any other changes and try out the new setup. top rpm should increase. If it is still low remove the mid rivet and retest.

Make only one change at a time.

hope it helps
ROB

 

[smithereenpsycho]

After drilling out the larger rivit in the Toe the machine is a night and day difference, took it to a strip to test the flat speeds and take off.
After 500 meters in 8 inches of soaking wet fresh snow it was pulling 94-95km at 8700-8900.

on a half set up track it was pulling 110km at 9100 so i think it's pretty much got it, just gotta get into the hils and see what happens, but thanks for all the info and suggestions guys! Now it'll be blowin the E-tecs off the mountain... which was my goal in the end.