Clutch this dummy

Backwoods M Max

Backwoods M Max

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Mar 31, 2011
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New England
Well like it says, here we go. I have finally been able to figure out what my gearing is on my mm (or at least what I think). I found a parts fiche that has the reverse kit for the mm which I have. Lists it as a 39t bottom gear so one tooth less than stock. Parts fiche shows the top gear as 21t which I doubt was changed given that the sled was trail ridden. This summer the dealer had to buy a chain because mine was stretched and it's a 70L, it would be too long on 19/39 gears I believe. Clutching is stock, no wear on the sliders or anything but I haven't changed the springs in the 3 years that I've had it (shame on me). I am anticipating that I will want to gear down now that I am running a 151" track and am really set up for technical riding. I picked up a 19t top gear which will give me a 2.05:1 ratio. Besides new springs, where should I start with tuning the clutch? Besides mountain sleds having different requirements am I best off to call tom hartman and have him put a kit together for me? I'm riding 0-3500' altitude, light motor mods.
 
I did see that when I was looking around for clutch kits. Your right there should be no reason to run a 70l chain in a mm because it's such a taller ratio compared to trail gearing. I'm at work and don't have the parts sheet from the chain case rebuild this fall to see what the shop put in it. I couldn't remember if it was 68l or 70l, I will have to see when I get home next week. The shop said that when it all went back together, the chain was stretched enough that the adjuster bottomed out without the chain being tight. Maybe I already have a 19t top gear and a 68l and the adjuster is almost used up. I see the reverse kit came with a 39t bottom gear, but a 40 was available. Maybe the shop that put it in was on their game and found a 20t top gear to keep the ratio at stockish. Being away for 2 weeks at a time on a small tug boat lets your mind wander, did I do this that and the other or not. And I have not pulled my cover off so I really don't know WHAT is actually in there. I have just been trying to figure it out by the parts list. I didn't ask the shop to count gear teeth for me but I should have.

What will it be like if I drive it with the 19t top gear and don't touch the clutches? will I just shoot through the secondary too fast and back shift early always keeping the revvs high? this is where I have ZERO knowledge. I prefer to get something that is pre-engineered then figure out why it worked after I have seen that it did.
 
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60 teeth total necessitate a 68L chain. 61 total teeth need a 70L. That's the cut off between the two. Now for gearing, there is more fun to be had when the gears are @ a 2:1 ratio. If ya can't do that, shoot for 1 tooth taller. For yours, I'd probably shoot for 61 teeth. Something like a 21/40. If they make it.
I like more of the short bursts of power verses the top speed. We have a 20/40 set-up on my sons 99 SX6 and it is an absolute RIOT. But then again.....you do have 100 more CCs.
 
I'm thinking for a tree sled which is what's I've set this up as the little taller ratio will be ok. It should pull HARD in short bursts when I need it. Just wondering how it will ride with that tall gearing and stock clutches.
 
The kid still has stock clutching in his. 136 Hartman extension, and drop brakets w/ the proper shock geometry adjustment and it rides beautifully. And USI Triple Threat powder skis for good handling and great floatation.
 
MM:s are easy to clutch with Heelclickers. Mine was spot on the second time I tried it, but mine is stock 141 with stock track.
 
Ask and you shall receive.

My sled is a 151 now with a serous diet.

Well once again Tom Hartman has proven why he is the best. As always he's super friendly and very free with information. I called him thinking I was ordering a full blown shift kit with a helix and found out I only need to change my springs and change the helix wrap. I got a nice little cheat sheet of notes out of it, and it was very insightful. Tom suggested changing to a W-W-W primary spring to lower my engagement to 4000 rpm and a Silver secondary and drop the wrap from 70 to 60. I can run the wrap 3+3 here at home then change it to 6+1 for out west with all the other things staying the same. He said that dropping the wrap will give me faster shift out when I'm sidehilling or digging a hole and need to pin it and get the track speed up in a hurry. I also got some insight to gearing which was good. He said running the 19T top gear is dangerous because the radius is so short that you can break the chain in a hurry and then the chain case explodes. At sea level tuning he said I've got the horsepower to pull at 1.85:1 ratio using a 21T top with the 39T bottom gear from the reverse kit. If I go out west to ride a 20T top gear will get me close enough to 2:1 that I won't need to worry about it. I've got a spare set of carbs that I can set up for altitude then I can just swap them before I head out west, perfect way to go.
Clutch Magic.jpg
I also got a little info on the setup on these sleds when they were delivered. They came from Japan set up for 5000' and had to be tuned from there. Even though the manual lists the stock setting as the base altitude it wasn't the way they came in the crate. So mine had to get set up for base altitude just like someone who bought one at 8000' would have to been set up for there.

I now have a set of springs on the way from Hauck so hopefully I'll get them by the end of the week or next Monday at the latest and I can get this thing set up and away we go.
 
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A couple of bucks said:
Cannot wait to hear the results!
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That thing looks like a blast. Did you find it wheelies better while still keeping the transfer bars with the skid set back? I've got straps, and the 2000+ skid geometry with rails.

I've kind of got a hard on for a 2000-01 phazer mountain lite to leave at my mother in laws for a mess around sled. Change it to 8 tooth extroverts, put in transfer straps and give it hell in the back 40.
 
Backwoods M Max said:
Did you find it wheelies better while still keeping the transfer bars with the skid set back?
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The skis are @ 1/2 inch above the snow when it's pinned. Had to back out limiter straps after the first run. WAY WAY too much ski lift. Just stock x-fer rods w/ the bottom(i think) teflon taken out. His hook up on semi hard park is a real neck snapper.
It really pisses off this 96 Cat 700 twin EFI. The Cat should take him. But every time seems to be an embarrasment for the Cat owner.
 
Sure.
Primary: Reed heelclicker spring, 5,2 grams in heel, 15 or 15,6 mm rollers, either will be fine as long as the washers on the heel bolt clear the rollers. 5 grams in tip. That's with stock 2'' lug track and 21/40 gears.

Secondary:

set up 1 (off trail and towing). Hauck roller secondary with hauck red spring @ 70 degrees. 44/38 dalton.

set up 2 (on trail riding and screwing with the newer sleds). Stock secondary, hauck red spring @70 egrees, 50/38 dalton.
 
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norwegian said:
Sure.
Primary: Reed heelclicker spring, 5,2 grams in heel, 15 or 15,6 mm rollers, either will be fine as long as the washers on the heel bolt clear the rollers. 5 grams in tip. That's with stock 2'' lug track and 21/40 gears.

Secondary:

set up 1 (off trail and towing). Hauck roller secondary with hauck red spring @ 70 degrees. 44/38 dalton.

set up 2 (on trail riding and screwing with the newer sleds). Stock secondary, hauck red spring @70 egrees, 50/38 dalton.
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thanks for that info!

backwoods: sorry for the hijack.
 
no worries. I got to ride around the yard today in some of the snow from blizzard "hercules" I paid more attention to the clutching today than I have in the past. I was grabbing right between 4500-5000 rpm so it's spot on for stock jetting so it should drop with the new springs. I probably didn't help that I was on the gravel driveway when I really looked at it and while I was grabbing at that rpm it wasn't until 5500 that I was actually starting to move. The clutches probably could be cleaned, and I'm going to give them a brake cleaner bath while they are spring free to get the dust out. I still haven't seen a charge from Hauck show up yet on my card, so I may have to call them monday and be like WTF, where are my springs.
 
srx700c said:
FYI, Yamaha's gearing chart shows 68L chain for 21/39 & 19/39.
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I stopped at the dealership on the way by today to get an extra copy of my parts invoice from the bill. It shows a 70l chain on the invoice:o| so I am skeptical as to what is in this thing for gearing/clutching. I just ordered a 68l 11 wide chain that I should have early this week. My NOS 20t top gear is going to be here Monday or Tuesday. Monday I'm dropping the oil, counting the bottom gear, changing the top gear, pulling the clutches apart to verify weights and helix angle and clean the dust out for when my new springs arrive. Got my fingers crossed that I have the right weights/rivets and helix in it still. I just had way too much trouble getting it up the ramp to the truck to believe it was geared right.

UpdateI got home tonight and ripped apart the chain case. The thing is a mess set up wise, and I can't say I blame anyone who was servicing this thing and going by the book. It does spec a 70L chain and the stock 21/40 gearing is at that 61 and up point of needing the longer chain. That can be traced back to the shop that put in the reverse kit, my guy just replaced like with like. It has a 21 top gear, 39 bottom gear and a 70L chain. The slack adjuster was just about maxed out on travel and the chain was making almost a 60 degree bend around the roller. Well here's what I found that really pissed me off, the slack adjuster roller was SEIZED and the sled hasn't been ridden any more than around the yard and into the truck to bring it over to my house, so it was like that when the shop had it apart this summer. Not too happy with the shop that did the work right now. That explains why the dipstick was full of metal shavings when I pulled it when I got it back, then full again after just running the sled in the shop on a track stand. That sharp bend and a stuck roller was making all sorts of trouble in there. I have a new bearing on the way from eBay and a pin and roller on the way from a mail order shop. I will be calling the parts house I ordered the chain from on Monday first thing to get them to change the chain to a 13 wide. Not sure why the woman pulled a 11 wide out of the book unless she was looking at the wrong line in a table, but I think I can catch the order before it goes out UPS tomorrow afternoon. Not a great start to winter but at least nothing locked up and left me stuck out in the woods.
 
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