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Big bore xm??

T

TreeThrasher

Free Member
Is anyone playing with any big bore xm's?? If so let's talk about what clutching and gearing combos are working.

I did an 860 on mine and am really happy with the engine. 150 miles and it is solid. Straight pump fuel, my own can, pins fully loaded with factory clutch components. Against our dead stock identical control sled the big bore stomps it. It's way stronger. However, when the load is really high on a big pull, I feel like the big bore sled is not applying its power as well as it should. I can loaf it hard enough with the clutch that I can pull the revs down, but shift remains at about 80%. This is a 163 with factory 19 51 gearing.

What is everyone else using for clutching and gearing?

Anybody that has any clutch and gearing setups that work well on big pulls feel free to chime in.

Thanks!
 
clutching

I personally think the stock gearing in the xm's is just fine. The stock clutching is really far off. I have never been a ski doo fan until last year when my Buddy Eric let me ride his xp that was clutched to near perfection and I finally saw the light. His set ups require no pin weight and pull hard in whatever rpm you're at.

Over the summer I had Eric do me a Trygstad 872 and we still havent found a sled that is set up similar that can hang with mine. My clutches stay cool enough that after the biggest pull I can come down and grab my clutches with my bare hands and not get burned. I couldn't be happier and I feel like he is worth calling and talking too about your sled.

Eric's Performance Center
435-851-9720
 
Big bores dont seem to like all the weight in them try taken weight out and compensate with a softer spring if you have a xm the helix is fine a bit of a soft spring in the secondary though. 412 ramps seem to work good in allowing you to take wieght iut of the pins and still allow for good back shifting
 
Ya the big bore xm sleds are pretty gnarly. A stock xm goes really well but both the trigger 872 I rode with and my 860 are substantially better than stock.

I talked to a friend that had Jason with team help him with his 872 xm a few days ago. Sounds like 441s, added weight, softer initial primary spring, straight 62 tied helix, and up one tooth on gearing is working pretty well. Speeds in the 45 to 55 range depending on load. 163 xm.
 
If the BB is making good power you will want to gear up and go with more helix than what is stock on the XM. Probably a stiffer sec spring as well if you go with more helix.
My 860 didnt like my 800 clutching, it took a different approach to get the power to the snow.
 
kevycox5 said:
I personally think the stock gearing in the xm's is just fine. The stock clutching is really far off. I have never been a ski doo fan until last year when my Buddy Eric let me ride his xp that was clutched to near perfection and I finally saw the light. His set ups require no pin weight and pull hard in whatever rpm you're at.

Over the summer I had Eric do me a Trygstad 872 and we still havent found a sled that is set up similar that can hang with mine. My clutches stay cool enough that after the biggest pull I can come down and grab my clutches with my bare hands and not get burned. I couldn't be happier and I feel like he is worth calling and talking too about your sled.

Eric's Performance Center
435-851-9720
Click to expand...

I would like to see if mine can hang with ya. Pm for number let's go ride
 
adam8781 said:
Your own can? Can you elaborate?
adam
Click to expand...

Ya, I build my own exhaust components that allow me to adjust pipe center section pressure and effective stinger length. I have found its an effective way to adjust power delivery and the point of peak torque to make a better big mountain package. I develop everything against a control sled, then when I'm happy with performance I log the numbers (heat and pressure primarily) so I can get back to a solid baseline after motor mods.

I added gearing today. This sled is way way better in every situation than our stock test sled. However, when I ride the stock 13 it feels like its doing all it can do with the power it has. When I ride the big bore sled it reminds me of a 60s muscle car....horsepower going every which way. Lots of loss between engine and track.

Can anyone explain the difference in loading an engine with additional helix angle and loading the engine with a lower clicker number? One does not replace the other I assume...
 
Its geared 21 49

I don't know that it increased peak speed much. But the sled did seem to carry a greater amount of ground speed than it did vs our stock 13.

Next week I will have our new quick change belt drive on this sled for testing. That will make it easy to take lots of different gearing to the hill and make pulls against a stop watch to see what works best.
 
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