Bottom gear

[Turboflash]

If 21/38 is the ratio you are looking for (.55) you may be better off running 25/45 (.56) as it run more efficiently (longer chain, less rolling resistance, greater circumference = less energy wasted). Others here have run that combo.

One would have to have a very sensitive and very accurate chassis dyno to measure the difference. In the real world, on snow, I doubt anyone could tell the difference. There are many other variables that would make more difference in 1/4 mile or 1000' or even 1/2 mile in a race.
25/45 is much more expensive to install than 21/38. Technically, on paper, I think a scientist/engineer could prove that you are correct but from a practical standpoint, it would not matter on snow.

 

[earthling]

One would have to have a very sensitive and very accurate chassis dyno to measure the difference. In the real world, on snow, I doubt anyone could tell the difference. There are many other variables that would make more difference in 1/4 mile or 1000' or even 1/2 mile in a race.
25/45 is much more expensive to install than 21/38. Technically, on paper, I think a scientist/engineer could prove that you are correct but from a practical standpoint, it would not matter on snow.

LOL.. yes, well, as an engineer, its just me thinking out loud and yes, I agree.

 

[Doc Harley]

Turboflash & Earthling....it's all the little
things. Taking advantage of every single angle he can. On paper & at the track. At the end of the day, he's the fastest guy.

That's not me.

 

[Turboflash]

Turboflash & Earthling....it's all the little
things. Taking advantage of every single angle he can. On paper & at the track. At the end of the day, he's the fastest guy.

That's not me.

LoL - totally agree. I'm not the smartest guy out there so I default to trying to out-power 'em. Hence, PEFI Stage 4 (330 HP pump gas) with option of 360HP with C16 and waste gate lock and high gearing w lots of long studs - 1/4 mile.

 

[Doc Harley]

LoL - totally agree. I'm not the smartest guy out there so I default to trying to out-power 'em. Hence, PEFI Stage 4 (330 HP pump gas) with option of 360HP with C16 and waste gate lock and high gearing w lots of long studs - 1/4 mile.

Well....that's too funny. Best answer yet! Lol.
I would love to be the guy that outsmarts everyone on Eco trail. But we know how that's goes. I'm the guy on Max 17, balls to the wall, squirting in my last oz of boostane, fighting to stay one ski ahead of the stockers. Lol. Oh well....at least we're having fun!?

 

[NYTurbo]

Yeah Scott Taylor gears are a bit pricey for sure

 

[sideshowBob]

I have been using Scott Taylor gears and the main reason is my desire to have a 15 wide bottom gear to match the top gear and chain width….but they are not cheap!

 

[Doc Harley]

I have been using Scott Taylor gears and the main reason is my desire to have a 15 wide bottom gear to match the top gear and chain width….but they are not cheap!

Doesn't seem dire to have a 15 wide bottom gear, but do understand your thoughts. Makes sense to me.

 

[Doc Harley]

Stock gear is 13W on bottom but you could use a 15W if u want. OEM is usually the cheapest

NYTurbo, Thank you for getting me the part #'s and source... Quick and painless.

 

[Doc Harley]

Wrapped that up this morning. Noticed my engagement changed about 400 RPMs higher. I'm assuming because of the gear change, my torque and engagement changed with it?

 

[DMCTurbo]

Wrapped that up this morning. Noticed my engagement changed about 400 RPMs higher. I'm assuming because of the gear change, my torque and engagement changed with it?

A gear change won't affect engagement.

 

[Doc Harley]

A gear change won't affect engagement.

Hmmm......what about switching from an XS825 back to a 8jp?

 

[STAIN]

Hmmm......what about switching from an XS825 back to a 8jp?

Maybe, is the 8JP a little thinner than the XS 825? That would make a difference if the distance to the sheaves has changed.
Like DMC says, gears wont make any difference.

 

[Doc Harley]

Maybe, is the 8JP a little thinner than the XS 825? That would make a difference if the distance to the sheaves has changed.
Like DMC says, gears wont make any difference.

I'm sure you're correct. Belts are definitely different dimensionally.
I ended last year with a XS825, and I'm going to start this season on the 8jp.
While the 8jp won't be as durable as the XS825, I read past posts where the 8jp is more consistent and crisper throttle.
As long as I don't max out my qay70s. If that makes sense.

 

[NYTurbo]

Tune to the xs825 forget the 8JP