Top rpm 9600

[zipclean]

Thanks Slush I may just try that as I never ride trails.really need to get the skis up and put more weight to the track.Also the ripsaw track is not much good insnow,great on hard pack.I raced my sons 800 Cat 121" 1 3/8" predator track, and in 8" of snow he stays right with me and and pulls away after 1/4 mile,I am spinning.On hard pack after I quit spinning I walk by him and pull away steady by 10 lengths and more.

 

[Turk]

I got anywhere from 2-5 mph diff in 1000' radar runs by strictly playing with the same secondary spring at different degrees of twist. We have an annual radar run...$25 for unlimited passes. Final rpm,s were the same at the finish line but a big variance in speed.

 

[Yamadog]

Mine was the same way. up till about 150 miles it pulled 9600 after that it pu.led 10,200 till 400 miles at 500 miles it was (key word) pulling 10,700 I would not touch the clutching until your broke in cause you'll just be chasing it.

 

[welterracer]

Currently 750 miles on my apex gt.. Pulling 9800 out of the hole and at about 30mph it is at 10,200 and holding..

 

[dirkdiggler]

If it,s hot it is also from slowing or stopping the upshift & holding the sled in a lower gear.Dirk dude...your flat out wrong on thise one!

The fact is if you increase the twist on the secondary and you get more RPMS your slipping the belt. When that happens you will notice an increase in clutch temps. It's not holding it in a lower gear it's stuck in the lower gear because the secondary can't fully open. This can be proven with a Black Magic Marker. Take your belt off and draw a line from the top to the bottom of both clutches. Go out and run it. I'll guarantee that will still have a portion of your line on the top of the primary and the bottom of your secondary.

If all Yamaha had to do at the shootout to make the Apex faster was twist the secondary to gain RPM I'm sure they would have done that instead of taking rivets out of the Primary fly weights.


Torsional twist should only increased when your looking increase your back-shift. Otherwise stick with the factory setting for all around use.

The belt gets hot becuase more torsional wrap stalls the initial shift in the secondary and slips the belt in the primary. Torsional wrap has its largest effect on the first 1/2 of the shift and eventually the primary will overcome it and it will shift fully. The final rate of the secondary spring does not change with more wrap. Wrap is used for much more than just backshift, its used to tune out an overshift on holeshot and well as calibrating the engines flash on holeshot,. Once the sled is moving the wrap hass less effect on the upshift than the side pressure of the spring.

Heat in belts and clutches is bad. When I clutch a snowmobile I'm looking to get to X engine RPM with little to Zero Clutch and belt heat. In a perfect world your clutches and belt will be cold. That means you are 100% efficient.

If you increase clutch heat by twisting your secondary to gain RPM your decreasing the efficiency. That leads to reduced belt life and poor performance.

The Primary is where you should set your full shift RPM. You should always clutch from front to back.

 

[TT670]

No kidding but to say you cant use the secondary to tune is wrong, its done every day, I dont think you understood what I was saying, Changing the secondarys wrap doesnt necessarily change peak RPM but rather it changes the rate of upshift and it can be done without smoking hot clutches. Clutching a sled is about balance, theres a number of ways of skinning this cat succesfully. I professionaly did ski doo clutching for a number of yrs, my business had the pleasure of setting up a factory backed grass dragger and sold clutch kits all over the US and canada so Ive been around the block on this topic..

 

[dirkdiggler]

No kidding but to say you cant use the secondary to tune is wrong, its done every day, I dont think you understood what I was saying, Changing the secondarys wrap doesnt necessarily change peak RPM but rather it changes the rate of upshift and it can be done without smoking hot clutches. Clutching a sled is about balance, theres a number of ways of skinning this cat succesfully. I professionaly did ski doo clutching for a number of yrs, my business had the pleasure of setting up a factory backed grass dragger and sold clutch kits all over the US and canada so Ive been around the block on this topic..

The Clutching from the factory is no different then a clutch kit. It was designed around X RPM. When you start making changes to the factory settings you change the entire package. In my book if you want more Full shift RPM you should take weight out of the Fly weights. If you want more Up-shift you would loosen your secondary. If you are going to be playing in deep snow and you want to hold the lower gear and you want more back shift you increase the twist on the secondary. But you never increase or decrease twist on the secondary to achieve your desired full shift engine rpm!!!


You know changing helix angles also changes full shift RPM. The steeper the finish angle the lower the full shift RPM. Just the opposite the lower the number the higher the full-shift RPM.

I'm well aware that people fine tune there secondary based on conditions to improve performance. They can change helix's and springs based on conditions. If it's cold out and you've got great traction a tuner might use a little steeper start angle on his helix. If he uses strait angles he might step the angle up a couple degrees because he's got the power and the traction to utilize the steeper helix. Just he opposite if the traction sucks and it's warm out he might drop the angle. He might even drop the belt down in the secondary slightly when traction is poor to put the belt in a higher gear to help the whole shot. Or if traction is just awesome he'll put the belt as high in the secondary as he can to get as low a gear as possible.


It's a fun game.