Looks like ya'll have got it covered. In just a year, we've came a long way in clutching on these things. Seems like everybody is on the same page, now, and we can begin to talk setups not without being misunderstood. These are sled type clutches, but the setup is different than a sled somewhat, with a low rpm 4 stroke motor, compared to a high winding 2 stroke like in most sleds, add to the fact, we run with different loads, like mud v/s dry ground v/s sand.

 

THIS IS WHY I LOVE THIS FORUM...
Post something, In a couple of hours you get this great advice, grab tools, mod and test...
all in the same day!!!

BTW,
Dont mean to intrude on the post "Backshift" and "Shiftout" concepts are kind of vague, can somebody illuminate me a bit!

 

backshifting is when the clutch has to downshift because of increased load. basically you hit a hill, mud, whatever that puts more of a load on the CVT, it has to downshift/backshift to a lower ratio to compensate, otherwise it will struggle with the increased load. it allows for more torque to overcome the added load.

shift out is when the weights in the primary have enough force to push the belt up the primary sheaves and down on the secondary sheaves. the weights have to overcome the primary spring force as well as the secondary spring force for this to happen. during shift out, the belt moves up the primary and down the secondary. ideally shift out happens at peak HP of the motor and stays flat in RPM's all the way through. for mudding, its a good idea to have shift out a little above the peak HP of the motor because of the load the mud puts on the CVT.

 

Thanks for the reply got wake. I will give the stock weights a try after I grind them down. As far as elevation goes, we run at around 4500' and the mountain is 600' in elevation. My RPMs are probably right where they need to be off the line, as I hit the hill and it gets steeper that is when my Rpms drop down to around 6800 to 7200. In dont think I can see much of a gain up the hill other then more power. I gess my goal is to get more speed up the hill. At its steepist point I drop down to 45 to 50 mph. I would like to get closer to 55. That would get me past the more modified Raptors. and even farther ahead of my kids with their 450s and Banchees.

I think I need some Gear, But if I was able to find someone that makes gears it would be a whole new clutch set up I Assume. I can live with that

 

check your shift out on flat ground to get an idea if its shifting out flat or dropping or increasing in RPM's. ideally as the load increases because of the hill getting steeper your RPM's should stay flat and the CVT should backshift to compensate for the increased load.

 

That make sense, So if the shift out is set up properly it does not matter how steep the hill, the shift out should keep the RPMs at its peak HP range. I am guessing on the spare stock weights,I will remove the weight from the sides or areas that dont make contact with anything.

I think I am starting to get the big picture. I cant thank everyoneanough for all the info. If I spend much more time on the site I am going to have to swap engines again and in stall a Turbo. I thought I had some good HP. You guys are in a way different league then my little 58 RWHP.

 

58 hp is plenty for most. i'm just now getting into engine mods. i can't wait to see what the work mrrpm is doing for me yields. i'm sure it'll be a huge grin.

with good backshifting, your RPM's may fluctuate a bit depending on the load, but you want to minimize that while the sheaves are moving. once your fully shifted out there isn't much you can do but rely on the power of the motor, which is less than peak, so it'll probably bog down a little.

make sure to remove mass from the weights in the same spot on all the weights. but before you do, do some flat ground testing to see what your bike is doing during shift out. where the mass is removed can have an effect on shift out.

 

When you say flat ground testing do you mean remove the cover and make a few runs down the road or hill and watch what the clutchs are doing?. What am I looking for. Full shift out of the primary and secondary clutchs and to verify full shift out should I mark the clutchs with a sharpie pen.

 

yes, use a sharpie to make sure you are reaching full shift out. you can try to watch the clutch, but it is very difficult. i watch it to get an idea of mph at the start of shift out and once its fully shifted out, then use that as approximates to keeping an eye on the speedo and rpm's for multiple runs. note the rpm's when the clutch starts to shift out and if the rpms stay flat or go up or down slightly, prior to being fully shifted out when the rpm's increase proportionately to the speed. report back with some numbers and we'll go from there.

 

I have done this before but never under a load, just on the stand. On the stand my shift out is around an 1/8" to 1/16"above the primary but on the secondary I am about a 1/2" from bottom or full shift out. I would guess that on the secondary you would not want to hit bottom at full shift out?. or would you set it up to just hit bottom.

Thanks for the help, I will set it up this week endand let know the results.

Its time to go to work, Damm.

 

Kevin wrote:

as I hit the hill and it gets steeper that is when my Rpms drop down to around 6800 to 7200.

This tells me you are not backshifting well. You are upshifting hard out of the hole....carrying good tirespeed, until a heavier load is applied...then the RPMs are dropping. Lighter primary weights or heavier finish rate on the primary spring might raise RPM's....maybe hold them a bit better....but backshifting is a function of the secondary. Now for straight flat, hardpack drags, I think we have found that the shallower helix angles such as the 650 helix will actually slow you down. BUT, I think in this case (uphill, sand) this may be the first thing I would try. (My background is mountain snowmobiles....shallower helix angle will upshift slower but provide better backshift and more belt squeeze)

 

dave, thanks for the input. it is definitely always welcome around here. i was just thinking about the upshifting with the 650 helix, but for the backshifting aspect, it would definitely be a good place to start.

 

Thank's Dave. I orderd 2) 650 Helixs, they had seventeen left. I was just about to bag the whole 650 Helix thing. It looks like it's back on.

 

Did Mrrpm ever make a multi-angle? I know we were discussion it last season....but I've been sidetracked sledding here all winter and haven't really been paying attention. (you guys DON'T want to see the pile of new clutching crap I bought, tried, and sidelined on the new Summit this year....Gaaaaawd, what a mess!)

 

I know there was some talk about it in the forum, I haven't heard if he has milled or tested one yet. I will have to ask.

 

I may be completely off base here, but if Kevin is running at 50mph at 7200rpm up the hill would he not be slipping on the primary just a bit?? Losing speed uphill??

Wouldn't adding a bit of weight to the Dalton's and having a stiffer secondary give him a bit lower gear while ascending up the hill keeping his rpm's up and having the most power where he needs it?? It doesn't seam that he needs every mph of top end speed just all the power that his motor can put out at the fastest speed the motor can muster with the load at peak power.

There may be a bit less wheel speed on the flat but quicker acceleration and holding speed while he goes up the hill, right?

Please disregard this post if I am on the completely wrong path.

 

You are completely on the right path....100%. Adding more secondary spring has a similar effect to lowering the helix angle. The biggest problem is the lack of selection of springs OR helix angles. I don't like real stiff secondary springs....but its a personal preference....



I doubt he's slipping the primary, but I still agree with your analogy.

I gained about 300rpm when I went to the 650 helix....and Kevin may as well. In which case....add a little primary weight = more HP to the ground.

 

DaveB wrote:

Did Mrrpm ever make a multi-angle? I know we were discussion it last season....but I've been sidetracked sledding here all winter and haven't really been paying attention. (you guys DON'T want to see the pile of new clutching crap I bought, tried, and sidelined on the new Summit this year....Gaaaaawd, what a mess!)

Yes, I've made some, completely useless for mud bikes, because they get so thin on the edge. The mudders ride on the tip of the helix, (in low range) and after about one pass, it rips the tip off. Remember, these helixs' are made from plastic. I've been running one in my turbo to good effect. It is only on the tip for a split second, and works really well. If the mudders had some lower gears, (working on that), they could be almost shifted out, and that would put them in the bottom, where the strength is. I've hired a gear designer to custom design me a set of gears for these. Depending on my equipment, and the gear design, I might make them myself, if I can't make them, I'll have them made. If the gear designer can come up with a design that'll work, I'm gonna sell them. This will also help belt life greatly, and won't take long to pay for the gears in reduced belt cost.

 

Cool thanks Dave, I was just thinking about when I put my stock tires back on when I had the same clutch set-up as when I am using my Laws.

650 Dalton Weights with hollow steel rivets green Dalton primary and red EPI secondary. The red secondary made more difference in the clutch than anything. With my stock tires I was able to run 68mph I could never get there with my stock clutching.

 

i didn't really like the red EPI secondary. it starts out too stiff and doesn't have a high enough spring rate, IMO. i think a higher spring rate secondary with a starting point between stock and the EPI red would be nearly perfect. high tension is important for backshifting, so the EPI will backshift better. the lack of secondary options really kills us in terms of really tuning the clutches. if we could get a roller clutch to reduce fiction and more helix options, good lord the amount of tuning we could do would be nearly infinite.

 

I agree Ganibis, but got wake makes a good point as well, So It's been sugestedthat Ilighten my stock weights and now I should add weight to my Dalton Weights. I guess there is no wrong answer, This is where trial and err comes in. It's a good thing I am heading to Sand Mountain for Easter week end, thats probably the best way to find my answer. I have a good radar gun as well as a GPSto check my up hill speeds.

 

till you know where your shift out is and what it is doing, you won't know for sure if you need to add or reduce mass from the weights. if you put in the 650 helix, you will most likely have to add mass to the weights to bring the RPM's down a little. course another question is where the peak power of your motor is, that will play a role in where shift out needs to happen.

 

Also think about what i said a few posts ago. YOu have it CLOSE the way you have it now. SO if all else fails, leave it set up exactly like you have it now and add a primary spring that will have a different finish rate that will riase your rpms slightly. I think if you mess with the weights, you need such a little raise in rpms that it would be harder to do with the weights and it would be easier to do with a different primary spring.

 

I will give it a try Danny, What color Primary spring am I looking for, and does any one know the part numbers for the Yamaha Rivits on the Dalton Weights, I saw them in a post some where but I cant find the post.

 

You are running a stock primary spring right now correct??