I have done the clutch mod to my 2K 500 auto. It's designed to give you more grunt on the low end and not cost you any speed on top. (Like we have it to give)It also helps out on the mid range power. It's not hard to do. I will try to give a step by step procedure for doing it. I also have a drawing to send to anyone who wishes to do it or attempt it.

Here is a list of the tools needed.
1. inch and a quarter socket
2. impact wrench, either air or electric
3. a hammer and a brass or steel drift punch
3. some way to compress a very strong spring.
If you have a spanner wrench you won't need the hammer and punch.
4. drill and a 3/8 bit and a file.

Instructions
1. Pull off the clutch side cover.
2. Loosen and remove the drive clutch pulley.
3. Remove the drive belt.
4. Loosen and remove the driven pulley.
5. Turn the driven pulley over and compress the spring.
6. Remove the spanner nut*.
7. Remove the sring retainer plate.
8. Drill (2) 3/8 inch holes in the retainer plate**.
9. Cleanup any rough edges on drill holes.
10.Reassemble in reverse order, making sure to install the rear pulley first, next belt, then drive pulley.
11. Torque nuts to 75-80 ft pounds.***Caution
12. Install side cover and have some fun.

Notes: *The spring stub is sticking through the square hole.
Place the cup side of the facing down.
**The square hole should be on the right with the cup side down. Drill your 2 holes between the top hole and the square hole evenly spaced close to the edge, without damaging the retainer sidewalls. Place the spring stub in the hole at the 1 O'clock positon.
***You will have to force the belt down into the driven pulley before tighening down the drive pulley or you could bend the drive pulley side walls.

I may have forgotten somethings, I just don't think so right now. I have a couple of pictures and a drawing to send to anyone who wants to try this.

 

SO this basically lightens it up so it will shift faster? Right??

 

Just the opposite Boner. It actually takes more revs to get it to start the driven pulley to separate. Thus you have slightly more
RPM'S being applied at low speed.

There is no actual shifting just the pulley's getting larger or smaller is how it works.

 

I guess I'm confused here-go figure! heh heh heh. So you just drilled two 3/8" holes in the driven pulley? How does that give more low end grunt? Yeah, if you have time would you mind sending the drawings or whatever you have, I'd appreciate it. You know how I love my LOW range! [img]i/expressions/face-icon-small-happy.gif[/img] If you get a chance, could you also post your findings on how well it works after you get a few miles on it???

Thanks man, best of luck!

Mike

 

Please send me the diagram also, Sounds pretty tough though.
Thank You
SLY

 

Minehunter,

What I mean by shifting is as the pulleys expand and contract they change ratio's, there for shifting in a way.

With there being more revs,this will probaly cut into your fuel mileage.

 

Boner

You could be right about the miledge thing. I know this is only supposed to let you run the engine at higher revs on the bottom till you get into the power and torque curve with lower forward speed. I don't think it will make much of a difference, but I'll find out tomorrow. I'm supposed to go on a 60 mile trail ride up in the mountains. Time will tell and I'll report the results.

 

Please send me the diagram also, Sounds pretty tough though.
Thank You
gpartc.[img]i/expressions/face-icon-small-cool.gif[/img]

 

Minehunter-
I'm very anxious to hear how your ride goes tomorrow, please fill us in on whether or not you think it is worth the time to do the job. While at my dealers this afternoon, I asked him what he thought, he said YES, definately do it, as with my larger tires, and all the logs I pull, that it would definatley help out a lot on low end, as well as make it easier on the machine at the same time. He said they do that particular mod to all their snowmobiles, and have had excellent luck with it. I'd like to hear your personal opinions after your ride, then if you think it's worth doing, I'll hopefully tear into it next week.

Also, if you wouldn't mind, let me know how the mileage works out with the mod. I've got the 145 in my 'Cat now, seem to be having really good luck with it-well, right up till the wreck. My 'Cat is at the bottom end of the first quarter mark, my Dad's machine did exactly everything I did, his is down to the bottom end of the last 1/4 mark-pretty good considering I've got the larger tires, and heavier weight!

Anyway, best of luck with the ride tomorrow, hope it goes well. Dad and I are going out as well, so it should be interesting to say the least. Take care, have fun and BE SAFE!

Mike

 

Obviously reviving an old post here.... If I understand this, you are adding extra holes to allow some variation in the pre-load (twist) of the spring in the driven clutch. Arctic has had this feature on their snowmobile clutches for years, I'm going by memory but I think my ElTigre has around 5 positions. It really does work, on the sleds at least. Are the drive clutches on the ATV's set up similar to a sleds, with 3 centrifigal counterweights to drive rollers on the spyder? If so, it may be possible to play with cam weights and do some tuning, especially with a machine with taller tires. The peaky 2-strokes in the sleds are probably much more sensitive to this.

Bri