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Discussion Starter · #1 ·
Sled is a 95 ext efi mountain cat 580...

Primary gave up about 100 miles after I bought a few weeks ago. (if you haven't seen the broken clutch puller thread check out the pic at the end for the devastation!)

Anyhow I got a used primary and put it on and I need some advice on set up.

The old (now broken) primary had yellow/green spring and A25 weights - I believe those are notched 49.5 gram weights.

The new (used) primary has what looks to be a redish spring and A54 weights - I believe those are un-notched 54.3 gram weights.

Looking at brown's it looks like my sled should have red spring and 49.5 gram weights stock.

With that info I've got a few questions for the clutch gurus...
  1. - how should I set up this clutch?
  2. - what benefits or detriments do I have by running the A54's with the red spring? Early engagement obviously, but what else?
  3. - what kind of set up would the broken primary be using the yellow/green spring and A25 weights?
  4. - Without buying parts it seems like I've got four combos to choose from...do I need to buy parts to set this up right?
  5. - I've fixed a very loose belt and replaced a weak secondary spring. I'm trying to cure a mid-range bog. Compression is good (120's and both sides within a few psi of each other. Plugs are brown and piston wash actually is pretty black I could only just make out a small streak of wash near the intake - might be too lean or too much oil? Prior to this the sled has been burning a full tank in 40 miles - horrible mileage. Is there a clutch set up that would be better for the mid-range bog and fuel economy???
One final question - for testing purposes, how should the sled drive? If I'm cruising at 50mph should I be able to slowly ease the throttle and accelarate or should I have to aggressivly add throttle to get the RPMs to come up to peak - accelarate to where needed and then throttle back to cruise there? Also, should I be able to hold any speed without adding throttle?
 

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While you're at it, I would definitely get a new primary spring also. The yell/grn should work well in that sled.
You also need to put the same size (or close to) weights back in. The reason for the notch on the weight is
for higher engagement because of the poor torque of that engine. Also your replacement clutch has more belt to sheeve clearance than the stock clutch, so for optimum performance and better bottom end you should re-shim the clutch for proper clearance. If you're ok with it being a little boggy off the bottom then you could use non-notched weights.
You need to check your gearing also. It should prob. have 19/40 in it. It might have 20/39 gears which would work ok, If it does'nt hold the R's very well you might want to throw a 49 deg. helix in it. I'm assuming you put a stock yellow spring back in the secondary??
 

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Discussion Starter · #3 ·
<div class='quotetop'>QUOTE </div>
While you're at it, I would definitely get a new primary spring also. The yell/grn should work well in that sled.[/b]
yel/green will work well with what weights? The 54's or the 49.5's?

<div class='quotetop'>QUOTE </div>
Also your replacement clutch has more belt to sheeve clearance than the stock clutch, so for optimum performance and better bottom end you should re-shim the clutch for proper clearance.[/b]
Why do you say the replacement has more clearance? They were both 6 tower comets, both off 580s, and the belt was loose before the old primary went out. I'm just not following how you know that the replacement has more clearance? Thanks for straightening me out on that one! I do have a feeler gauge on my list of stuff to bring to the next session - what am I looking for on belt to sheave gap -.060 - .020 or what?

<div class='quotetop'>QUOTE </div>
You need to check your gearing also. It should prob. have 19/40 in it. It might have 20/39 gears which would work ok, I'm assuming you put a stock yellow spring back in the secondary??[/b]
Stock is supposed to be 20/39 - haven't had the cover off yet. Yep - yellow spring in secondary.

<div class='quotetop'>QUOTE </div>
If it does'nt hold the R's very well you might want to throw a 49 deg. helix in it.[/b]
Helix is stock 51* - so a 49 would make more throttle response?
 

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I have a '96
Yellow /Green primary
EPI adjustable helix set around 47-48
19/40 gears
48.5g weights AC pn(0646-080)
This combo worked the best for me (4000'-6500')
:beer_cheers:
 

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Discussion Starter · #5 ·
thanks for the tip - I'm looking to see if I can find a 49* helix today for testing tonight.

Did you have to go with a shorter chain on 19/40 gears?

is your a ZR or an ext? I understand the ZRs have a few more horses due to porting, pipes, controllers, etc... so I probably wouldn't want to copy a ZR set up exactly due to the hp difference
 

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Discussion Starter · #6 ·
ok well I did quite a bit of swapping and testing...

stock set up sucked! (49.5 gram with red spring and yellow secondary spring in the middle hole) Don't know if it's due to the condition of the red spring (couldn't find one in town)

Then I tried the same thing with the secondary in the 4th hole. Not much different.

Then I tried the yellow green spring in the primary (again not a new spring).....I really thought this fixed it. I ran a half dozen or more test runs and didn't notice the bog...just about when I was going to pack it in it started bogging and then got as bad as before. One observation with this setup - the weights didn't seem to rest on the spider with the clutch fully open...with the clutch off if you flipped it end over end you could actually hear the weights clang into the spider when you flipped it upside down. Does the fact that the bog was gone and then came back scream "BELT"???? It seems to be in fine shape - I'm going to pick up a new one to be sure, but I just don't know...oh and I gues I'm going to buy an 020 belt - they tell me that the 012 (stock) is the same dimensions, but the 20 is a harder compound.

With the bog back I tried the 54 gram weights with the yellow/green primary spring. The bog was gone. I could cruise at any speed in the power band and also could accelerate gently from any speed - I could also accelerate aggressively from any speed. The top end RPMs were quite different though. It was running in the 7800 range when I pinned the throttle. Above say 50 mph - if you were just cruising and pinned it the RPMs would jump, but not the big jump that I was used to with the other set ups.

That's how I left it...one last ride this coming weekend and it's at least driveable. I'll mess it with again next season after I get a chance to tear into the chain case and count gear teeth...who knows, maybe someone geared it high and that's goofing up the clutching...Once I know what the gears are (and if I want them that way!) I'll get new primary springs and a set of weights smaller than these 54's (way too big judging by the low engagement and reduced top end rpms) and do some more tuning.

Regarding the fuel consumption - all of my testing ran about 35 miles - and once again it burned a tank of gas. Two theories going I guess - either it wasn't a good test because I had the bog for the vast majority of those miles... -OR- it's not clutching related! I repeatedly pulled plugs after running with the bog and they continue to look good. Piston wash is unchanged too - mostly black with just a hint of wash visible - guess I'm bringing lots of gas this weekend!
 

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Discussion Starter · #8 ·
Cam - do you ride that setup closer to sea level with good results too? I'll primarily be below 4,000' and only playing in the mountains occasionaly...
 

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I don't ride it much anymore but it works good at home which is 2400'
I think a steeper helix and heavier weights at this elevation would be ok though
it is a bit high in revs at 2400' the setup I mentioned before is basically only for 4-6000'

hope this helps :D
 

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Discussion Starter · #10 ·
Ran it over 50 miles this weekend (awesome check out the pic from Arctic Man) and no bog at all.

Exactly as I described last - top end rpms are down a bit with the too heavy weights (7800 instead of 8400) and the upshift when jamming the throttle wasn't as dramatic as it should be, but I kept up with the crowds so was happy!

I did still have the 4 miles per gallon problem - ugh - that hurts the wallet! I'm going to think about tearing the tank off this summer and checking for leaks.

Thanks for the help.

Oh and as for the bog - it has not come back since I put yellow/green and 54g weights in the primary. If it was a fuel/electrical problem am I correct in thinking that I could not have fixed it with any clutching set up? If that is true then I think that because I "fixed" it with clutching that proves it's not any other problem. (stator, cdi, etc)
 

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