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Discussion Starter #1
Ok guys, I've been wanting to tweek the clutch for a long time but due to last year's rotten weather, I had to wait till this year so here goes;

I have a 96 670 mxz with 685 CC overbore wiseco pistons, trail porting, head shaved to .065 squish, carbs at 42.5 mm, Y pipe mod, air box gutted, cudney cluch kit, 25/44 gears, 670 HO crank, shorty boots, 136" track with 1.25" lugs and ridder is 230 pounds.

Where should I start for pin weight and ramps and what RPM's should I be running at? I'm mostly going for trail ridding but will do lots of powder.

PS: anything else I could doo to the sled? I'm running out of idea's, I already have ETS, Precision skis, 42.5" widening kit, a 5" raised seat and handlebar riser (feels exacly like sitting on REV) will post pics as soon as I dont forget the camera ???
 

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If I was you I would drop the gearing to 24/44 and get a set of those heel-kickers for the clutch. Suppose to work very well for trails, will make your clutchs shift hard with good excelleration. And running wiseco pistons? thats a nono ! Lose them and run stock bombardier pistons . Wisecos , Ive seen them expand faster than the jugs and heat size on a regular bases . Just my 2 cents
 

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Discussion Starter #3
Yeah, I know about the wiseco thing but Bombardier doesn't make a double overbore piston for my sled. Last owner had a ring break and had to go to wiseco.
 

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AC, there is nothing wrong with wiseco pistons, as in anything they have to installed properly, with the proper clearences. A scuffed piston because it's in to tight of a bore, is the fault of the installer not the piston. What doo you have in your clutches now? As in Pin weight, ramps, spring and helix and is there a prob you are have with your current set-up? What are you lookin for?
 

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I'm assuming you're not running studs. Why gear down? Once the track breaks loose you're going nowhere. I like the 228 ramps for trail riding. Stock solid pins and around 160-320 or 200-290 for a spring. You should be @ 7900-8000 for rpm. Try clicker 3 or 4. On the secondary maybe a Goodwin blue spring @ 18 lbs and a straight 50 cam. If you find you're in 1 or 2 for a "clicker" position try a bit more pin weight. Maybe 17.5 - 18.5 grams. Just some ideas.
 

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Discussion Starter #6
mr670

Curently I have 235/325 primary spring, secondary is set at 20# and ramps are stock. The problem I was having last year was not enough RPM, It was running 7800 on clicker 6 but since RPM's are usually less on doo's, I might of been getting around 7600-7700. I'm just looking for a start up point to minimize tunning time.
 

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Stock set up for a 96 mxz 670. 26/44 gears-- 286 ramps --- solid pins --- 160/230 spring --- 15.4 lbs secondary spring preload
 

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First check your tach they are low.....with the y pipe mod the motorshould be happy around 8000/7900....Ilike lower gears22 or 23 /43...this will bring your rpm, up with the clutching you have...
WHAT RAMPS DO YOU HAVE?
 

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Discussion Starter #9
I have stock ramps, 286 and 50 degree straight helix.

I will probably have my tach calibrated, anyone knows where to doo that?
 

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With that spring and everything else stock, with that preload your rpms should be off the scale, somethings not right unless you ride at 10,000 ` or so.
 

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Yea..something doesnt sound right...unless you got 20 gm. pins in there? That sounds like agoodwinn ssring is it posible someone put some of a goodwinn clutch kit in it ?.....
 

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Discussion Starter #12
I've put in a cudney clutch kit. That's where the P spring comes from. I also had a 1.18 full block track last year and noticed that it was a lot harder to pull the rpm's. The sled was running good though, I was beating a modded summit 670HO that had pretty much the same setup as mine so i don't know what the problem could be. That's why I wanted to try a different pin weight/ramp combo this yr.
 

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AC, the first thing I would doo is check that 235-325 spring, make sure it's still at spec. Get some adjustable pins and add some weight 17.0 to 19 grams and may be a 50-47 helix. Just wait for the snow and test away.
 
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