I want to gear down!

[2001srx700mod]

I have an sx-r 700 with some mods and want more hole shot. My buddies polaris xc700 did some gearing and got a better hole shot. Seems like every one i talk to tells me to add a tooth on the top and others say drop a tooth any good top/bottom hole shot ratios out there?

 

[Vmaxin]

okay well your holeshot is only as good as the traction you can get. Like i have 23/40 gearing in my VMAX and i still spin a bit, i would say it more relies on your suspension for the holeshot. unless you can legitimately hook up then gearing down is not gonna help you. however if you want faster acceleration you would want to use # of driven teeth/ # of drive teeth and that will give you a ratio, the higher the number, the better the acceleration, provided traction is available.

 

[chris700readhead]

If you want better acceleration you want a smaller gear up top or a bigger gear on bottom. Example if your gearing is 23/40 your gear ratio is 1.73:1 and if you go 22/40 your ratio is 1.81:1. The higher the number the more acceleration, which lowers your top speed. The lower your ratio number the more top speed you will have but it will take you longer to achieve it. My sx is 22/40 and it comes out the hole pretty good but I'm not a small Guy. I believe if you put a smaller spacer on the bottom of your transfer rods it will allow the sled to roll back on the track more and give you better traction for the hole shot. Chris

 

[2001srx700mod]

Can you run a 22/40 gear on stock chain ? Is that extra tooth on the bottom noticable? I have no problem getting it to the ground how about a 21/40 on the stock chain ?

 

[sideshowBob]

I used to run the stock 99 600 SX gearing in our 121" piped 700SX and it worked very well for acceleration and good top end.
99 600SX gearing is 21/40 = 1.90:1 [70 link chain]

This works well with tripple pipes that have already raised the shift RPM. Raising the shift RPM is not unlike gearing the sled up when your gearing is left stock.
ex: stock shift = 8500
tripple pipe shift = 9200
9200 divided by 8500 = 108 %
As you can see you have effectively increased theoretical top speed [just like gearing up] by 8% just by adding pipes and raising RPM. This may be fine for ice radar runs but would likely slow acceleration.

If your stock gearing was 23/40 = 1.74:1 multiply that by 8% = 1.88 :1.
So you would have to gear down to 1.88:1 just to maintain what sled had stock for gearing and take advantage of new power for acceleration.

Modding a sled is much more then just bolting parts on...it all has to work together and match your application.

Its all about the Math.

Bob

 

[Devilin AblueDress!]

I have an sx-r 700 with some mods and want more hole shot. My buddies polaris xc700 did some gearing and got a better hole shot. Seems like every one i talk to tells me to add a tooth on the top and others say drop a tooth any good top/bottom hole shot ratios out there?

Million dollar question......What gears/chain do you have on sled? Assuming its stock and making plans to change to any of the gears/chains mentioned in this thread to pull cover and realize.....DOH! Thats whats in there now!

 

[staggs65]

gearing is 21/40 = 1.90:1 [you would need 68 link chain]

WHAT????? I need to fire my junior mechanic. I just told my yamaha apprentice (LOL) to put 21/40 in my viper with a 68 last weekend and he said it woudnt go. I guess I have to check his work from now on. lol
carry on....

 

[snowdad4]

never been able to complete that set myself with the 68. always about 1/2 a link off.

if theres a trick to making this fit, please do tell! at this point, i would stand behind your jr mechanics instincts.

 

[sleddineinar]

OEM specs for the 2000-2002 700mm shows 21/40 gears and a 70L chain. Same for the 2003 Mtn Viper and Mtn RX1.

 

[A couple of bucks]

Doesn't 60 total teeth=68l & 61 and up=70l ?

 

[jasburrito]

23 39

My gearing is 23 39 600 twin. Could i go dow to a 22 39 and still use my same chain?
thanks

 

[staggs65]

as couple a bucks said. 60 is usually the magic number on the proaction sleds. add together the top and bottom gears. 60 and below 68 link, 61 and up 70 link.

 

[jasburrito]

thanks for the fast reply. Now I get it. Gonna finish working on my sled. changing leaking side heat exchanger. I put a layer of ultra black on the spot were they leak (on the new used 1 before install.) Also putting rebuilt shocks back on skid. Glad I did. Found a bushing missing on a shock relay rods bent . Limiter straps pulled up way high and shock was way over sprung. Should ride like butter when its all back together. ( Add snow)
cheers