boondoggle
Extreme
Tbyrd already helped me out a lot with advice on how to deal with this problem but I still don't understand why the rpms would be higher now. I've only ridden once with the 151 and it was in bone dry powder, unpackable, so hook up was minimal. But after putting on a bigger, heavier track with a lot more lugs I only expected rpm's to go down. More weight, more surface area, more resistance. But after this first ride I found I was hitting the rev limiter when trying to power out of spots and gunning it, and I kept getting up around 12,200 rpms when wide open. To my way of thinking this modification should have dropped Rpm's. What am I missing?
I still want to ride it in some different conditions before I fool with rivets and such but I'm wondering if higher rpms are somehow to be expected with this mod. Tbyrd seemed to suggest it was.
I still want to ride it in some different conditions before I fool with rivets and such but I'm wondering if higher rpms are somehow to be expected with this mod. Tbyrd seemed to suggest it was.
kodak
TY 4 Stroke Junkie
what top gear are you running some people suggest an 18 or 19 tooth like they run in rtx if she can handle it that will help go faster also did you have any clutching before your mod beceause i would have figured an lower rpm also.
yzman
Expert
i have the mod done . But i also got a clutch kit and geared down to a 17 top from a 19 top at the same time . So i cant say if it made my rpm rise. If your not sea level you have a 17 top stock . But it's very weird that it gained rpm
I think it has to do with the secondary clutch. In theory you are turning a heavier track slower thus not opening up your secondary as fast. (Its making it stay in a lower gear ratio longer) Thats why you have to make the primary pull harder from the begining to make it shift out quicker.
Disclaimer: I know very little on clutching!
So don't qoute me.
Disclaimer: I know very little on clutching!
So don't qoute me.boondoggle
Extreme
Yup. I do have the stock 17 tooth top gear.
I think I'm following you Tbyrd. Basically when I'm wide open the sled is hanging in too low a gear because of the added resistance. The secondary isn't opening up far enough to hit a higher gear and drop my rpm? Is that it?
I saw on another post that you have done some more experimenting with your weights. Have you settled on anything yet? Or do you still recommend (3) 17.3 gram rivets with a C2 setting on the secondary spring load?
I don't care about the top speed. I'm worried about hitting the rev limiter all the time and just not operating at the optimal rpm.
I think I'm following you Tbyrd. Basically when I'm wide open the sled is hanging in too low a gear because of the added resistance. The secondary isn't opening up far enough to hit a higher gear and drop my rpm? Is that it?
I saw on another post that you have done some more experimenting with your weights. Have you settled on anything yet? Or do you still recommend (3) 17.3 gram rivets with a C2 setting on the secondary spring load?
I don't care about the top speed. I'm worried about hitting the rev limiter all the time and just not operating at the optimal rpm.
boondoggle
Extreme
Woops, I quoted you. But I won't hold you liable. Here, it's in writing.
No change to the drivers? One thought I had is maybe the drivers are ratcheting. I know you would think you would feel and hear it but something to consider.
Also how old of belt are you running?
Also how old of belt are you running?
boondoggle
Extreme
Kept the stock drivers. But I definitely cannot detect any ratcheting. Acceleration and rpm build are smooth all the way through wide open. However I am running the track real loose. With just a little over a 3" set back I'm already near the back of the adjustment so I didn't want to tighten the track if I didn't have to.
The belt is the red letter kind. 8GK I think it says on it. It came with the new sled and the sled has less than 1200 miles.
The belt is the red letter kind. 8GK I think it says on it. It came with the new sled and the sled has less than 1200 miles.
mark your primary clutch with a marker and go run it and see if primary is shifting all the way out. When you check it the marker there should be a 1/4" of marker left on the sheave.
phazo1
Newbie
Same problem
I don't want to hijack, but I just finished my set back and took it for a weekend. I played in the deep powder and noticed similar problems, I was all over the rev limiter. Mods I've done, cold air intakes, Ultra Q muffler, stage II clutch kit, fuel pressure regulator, all but the muffler came from Schmidt Bros. I am looking for assistance as well.
I don't want to hijack, but I just finished my set back and took it for a weekend. I played in the deep powder and noticed similar problems, I was all over the rev limiter. Mods I've done, cold air intakes, Ultra Q muffler, stage II clutch kit, fuel pressure regulator, all but the muffler came from Schmidt Bros. I am looking for assistance as well.
boondoggle
Extreme
What do you mean, run a marker line from bottom to top (inner to outer) of the primary. Then are you saying there should be a 1/4" left at the top that doesn't rub off? And what will that show? That I need to up the weight?
boondoggle said:
yes from bottom of the sheave to the top that the belt rides up, that will show that the primary clutch is shifting all the way out. remember the spring in the primary controls engagement rpm and the weights control maximum rpm.
An example is my sled ridden from 0-1000' and me with gear ats 285 lbs. with a 144" X 1.75 Camoplast Back Country with 17/41 gearing. I changed my engagement to 3500-3800 rpm with stock arms and 17.2 weights (4.5 grams) in both holes. At holeshot on the trail and the powder its 12,100 and drops immediately to 11,400-11,100 just where it needs to be. Remember weight of rider and elevation factor in with track profile and motor mods. phazo1 with your stage II you will have to change your primary weights according to Schmidt Bros.
I'm running a 19 tooth top gear with a 151 challenger 2.3 inch paddle. I changed my primary clutch arm rivets to 17.2 inner and 13.9 outer but have another set of 17.2 to put in the outer if the 13.9 aren't enough. Im waitting for a little better snow conditions to test the rpms under a heavy load. its close now. My secondary is set at C2. I do have 4 bullseyes and the excell exhaust with a fuel curve enrichment. I also run the ultimax belt which is alot softer compound then the yami and helps the primary clutch grab hard. (no slipping) All this at 300 ft above sea level. I weigh about 210 with all my gear on and have shed about 30lbs off the machine with mods. Hope this helps, might be able to establish a baseline to start from.
boondoggle
Extreme
Thanks. That all helps. Now I just need a chance to get out and experiment.
Emerygs
Newbie
I just finished the same mod (14.25 x 151 x 2" Skidoo track.) I have also had the issue of over revving. (12900)
I cleaned the secondary, removed all the grease, polished and lubed with silicone spray (not the sheaves, only the helix) and in the A1 position it seemed to help a bit (12000 vs 12900). I think A1 is stock on these. Remember to mark the original spline position when you take the secondary apart to clean it, I forgot and had to guess. Also I removed one shiv to have the belt engage sooner. I thought this might put just enough load on the primary to cheat it!
It seems like the 151 mod frees up the track cause it makes a smoother entrance to the snow. Feels like I have better top end and bottom end with this track. Is there a chance this mod makes the sled so much more efficient that it over revs?
Anyways, from my two stroke days I would say that if I was over revving I would want more load on the engine at WOT. To get this I would have put bigger weights in the primary so it hits harder and loads the engine. Or I would have loosened my secondary to allow the sled to go into overdrive sooner thus cheating and putting more load on the engine.
Now that was two strokes and the torque was very different. Hopefully the principals are the same, going to the mountains this weekend. I guess I will find out! Have a friend with a Turbo Nytro and he always sets it up to hit the rev limiter at lower elevation (around home) and when he gets to the mountains it runs perfect due to the slight power loss at elevation.
Hope this helps. Best of luck boondoggle! Keep experimenting, anything is better than stock on these IMO!
Emery
I cleaned the secondary, removed all the grease, polished and lubed with silicone spray (not the sheaves, only the helix) and in the A1 position it seemed to help a bit (12000 vs 12900). I think A1 is stock on these. Remember to mark the original spline position when you take the secondary apart to clean it, I forgot and had to guess. Also I removed one shiv to have the belt engage sooner. I thought this might put just enough load on the primary to cheat it!
It seems like the 151 mod frees up the track cause it makes a smoother entrance to the snow. Feels like I have better top end and bottom end with this track. Is there a chance this mod makes the sled so much more efficient that it over revs?
Anyways, from my two stroke days I would say that if I was over revving I would want more load on the engine at WOT. To get this I would have put bigger weights in the primary so it hits harder and loads the engine. Or I would have loosened my secondary to allow the sled to go into overdrive sooner thus cheating and putting more load on the engine.
Now that was two strokes and the torque was very different. Hopefully the principals are the same, going to the mountains this weekend. I guess I will find out! Have a friend with a Turbo Nytro and he always sets it up to hit the rev limiter at lower elevation (around home) and when he gets to the mountains it runs perfect due to the slight power loss at elevation.
Hope this helps. Best of luck boondoggle! Keep experimenting, anything is better than stock on these IMO!
Emery
