MM700 Jetting (stock, 3-6K')

[ForrestBault]

I'm brand new to sledding. My background is trials so the snow is a whole new ballgame. I've purchased a 2000 MM700 bone stock with 1042 miles. I live and will ride between 3-7K feet. It seem all my searching has lead me to jetting specs for piped/mod sleds, or at a lower elevation. I cleaned the carbs the first day I had it. And adjusted the oiler cable per the book. -

- It has 138.8/137.5/137.5 and 52.5 pilots across, with 1 3/4 out. Is this a proper starting point?

-Can I lower the belt engagement from 4600RPM? Sure would be nicer for my puttin' around if it were around 4000RPM.

-I have 1.5mm side to side play of the secondary on the shaft it rides. Is this normal?


This should give me a good start. Thanks!
Forrest

 

[Backwoods M Max]

From the service manual PTO jet is 145, middle and mag jet 143.8 and pilot 1.5 turns. but that is also for sea level. If you were to re-tune your clutch for a 4000 rpm engagement you could possibly have issues with being too low in the power band to get the sled moving without bogging. It's kind of like revving the motor to a certain point and letting the clutch slip a little bit as you accelerate and hold constant rpm's in a standard car. Once you start moving assuming your not in deep snow the belt will up shift and rpm's will drop. If your only riding at clutch engagement speed the belt won't last long from constant engage/disengage.

did you also adjust your throttle cable before adjusting the oil cable? you want to check and make sure that TORS functions with the throttle cable setting the way it is then do the oil cable last. I just did mine last weekend, my idle was a little low with a new belt on it so I had to bring up the idle, adjust the throttle cable, check TORS then do the oil to make sure everything was book spec.

 

[Backwoods M Max]

BTW stock pilot is 45 per book spec at sea level

 

[ForrestBault]

did you also adjust your throttle cable before adjusting the oil cable? you want to check and make sure that TORS functions with the throttle cable setting the way it is then do the oil cable last. I just did mine last weekend, my idle was a little low with a new belt on it so I had to bring up the idle, adjust the throttle cable, check TORS then do the oil to make sure everything was book spec.

Yep- It's all adjusted to spec.

 

[Mysledblows]

Jetting sounds pretty close. Used to run 130's at 9000+

Softer initial rate on the primary spring will do that.

Yep. In theory it floats to align with the primary as the motor moves on the mounts.

 

[ForrestBault]

Softer initial rate on the primary spring will do that.

So find a softer primary spring??

 

[Mysledblows]

If you want a softer engage and the same shift you need a softer initial rate and about the same finish. What is the color code on your current spring?? that will tell you what you have and then pick something with a little less preload on the bottom.

 

[ForrestBault]

Yellow-White-Yellow

Do I need to lube any of the pivot points in the clutches. I havnt even started researching clutch stuff yet.

So do I need less preload but still the same Spring Rate? Like maybe a Yellow-Silver-Yellow?

(http://www.totallyamaha.com/snowmobiles/aaTECH/drivespecs/primary_springs.htm)

 

[Mysledblows]

That should be pretty close to what you are trying to achieve. Or a Green-Silver-Green would work too.

No lube - just attracts belt dust. Clean and dry is the Yamaha way.

 

[ForrestBault]

Has anybody tried this on a stock machine? What is the actual engagement RPM?

 

[Mysledblows]

I'll check my notes from when ours was stock and see what we were running for a spring.