snomoquad sprocket

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snomoquad sprocket

Postby chainreaction » Thu Oct 31, 2013 4:59 pm

Looking for some advise.
We have been doing some rebuilding on Jordans snomoquad. It is now longer (90" wheelbase) lighter (350#) and alot stronger than it was when we acquired it last year. We have rebuilt almost the entire chassis, changed it from a 600cc Ski-doo to a 700cc Yamaha SRX triple, moving the motor 3" forward and adding 8" to the chassis behind the motor. The SRX is rated at 142hp stock. It will have a 90" wheelie bar before we begin racing it next year. And yes I know that once we get it tuned in we are going to need more rear tire.
Looking for advise on rear sprocket size, material and source. My thoughts were somewhere a round a 92 tooth.

Before
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After we front halved it, still Ski-doo powered
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After we back halved it to fit in the SRX motor
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First test run (no footrests!)
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Last edited by chainreaction on Sat Nov 09, 2013 3:05 pm, edited 1 time in total.
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Re: snomoquad sprocket

Postby THE BOSS » Thu Oct 31, 2013 5:35 pm

I'll have to check with the snomo dudes for sure, some run big on rear, some don't, they all end up with 600 to 700 ratio and that depends on the HP
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Re: snomoquad sprocket

Postby THE BOSS » Thu Oct 31, 2013 5:35 pm

I'll have to check with the snomo dudes for sure, some run big on rear, some don't, they all end up with 600 to 700 ratio and that depends on the HP
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Re: snomoquad sprocket

Postby Triple Threat » Mon Nov 04, 2013 8:12 pm

Most snowmobile bikes I have seen have a 80-82 tooth rear sprocket with a 12-13 tooth front sprocket, but there are some odd ball setups. I have a 71 rear and 14 front with about 85 inch rollout tire. Shocker on the other hand I think has a 92 tooth rear with 12 tooth front with a 96 inch roll out tire. You can get almost any gear setup to work consistently once you get the clutching tuned in.
Sprocket specialists make sprockets up to 71 tooth
Rebel Gears makes up to 96 tooth, I haven't seen anything from them but was on another ATV forum for a similar question.
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Re: snomoquad sprocket

Postby dano » Mon Nov 04, 2013 8:39 pm

Had a stock zrt 800 based biked before @ 148 hp and the 12-80 gear combo worked really well with a 26 inch tire.
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Re: snomoquad sprocket

Postby chainreaction » Thu Nov 07, 2013 7:06 am

The bike currently has 12-64 for sprockets and runs on 24-11-10 12 paddle Skat-trak Extreme paddles.
I run 12-72 on Chainreaction and figured around 72 would be a good starting point for this setup. I was leaning towards closer to 82 though. The 72 is a Sprocket Specialists item.
We have a couple of racers, (our two fastest snomo's) that both run around 92 rears. They seem to come off the line easier without such a violent launch. I know alot of that has to do with the clutch tuning though.

What were you running for numbers at 148hp? Approx weight?
I'm always looking for benchmarks to have a realistic idea of where we should end up when we start getting the setup ironed out.
Last edited by chainreaction on Sat Nov 09, 2013 3:01 pm, edited 1 time in total.
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Re: snomoquad sprocket

Postby dano » Sat Nov 09, 2013 7:52 am

Bike ran 4.2's at @ 76 mph but it was a dune bike had full suspension and weighed 499 pounds its self.
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Re: snomoquad sprocket

Postby chainreaction » Mon Jun 16, 2014 7:18 pm

We have finally gotten the bike to the track. At the first race we had a number of first outing gremlins to contend with. As we worked through them we quickly hit the limit on the tires. From 60' on it was blowing them away. Jordan did manage to go 4 rounds before he pulled the bike from competition due to steering issues.
Second race, now with bigger tires 26x12x12's, got through time trials, but still not hooking up second half of the track. It is launching violently and by around 200' the ass end is starting to skate around. It seams to be shifting past the tires ability to keep up. Tried 7psi, 10 psi and 13 psi. no major difference. I'm thinking we are ready for a bigger rear sprocket and some clutch tuning. Have worked it from 4.58 to 4.48 to 4.41

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