gearing attak

[BubbaGoFast]

Cool thanks LB. That's about what I figured on one on top equals two on bottom but it wasn't official, just figured 20/40 would be exactly that so I figured that I had to be close. So thanks for confirming the other question I had is I didn't think that yamaha made a 37 bottom 38 was smallest but not 100% positive on that. Well you guys are awesome I've used this site for about 2 years and I just finally became a member. Talk to you guys later. Oh that's right I tried 24/39 but you say that is too tall so should I go to 24/40 for the straightest chain and then clutch from there?

 

[Charged RTX]

I am not sure why everyone is so concerned about a "straight chain" . The tensioner side of the chain only has the the amount of tension you set with the tensioner. it takes no power to move that chain over the tensioner.The other side is what tightens under load and turns the gears. If you consider you are spinning a 40lb track, clutches, belt, crank, cams, internal gear reduction with chain, cam chain, pumps, shafts etc. The bend in your chain makes about as much difference as what you ate for lunch!

 

[LazyBastard]

Cool thanks LB. That's about what I figured on one on top equals two on bottom but it wasn't official, just figured 20/40 would be exactly that so I figured that I had to be close. So thanks for confirming the other question I had is I didn't think that yamaha made a 37 bottom 38 was smallest but not 100% positive on that. Well you guys are awesome I've used this site for about 2 years and I just finally became a member. Talk to you guys later. Oh that's right I tried 24/39 but you say that is too tall so should I go to 24/40 for the straightest chain and then clutch from there?

I would suggest that if you are looking for fuel mileage, that you don't worry about the gearing or anything going on in the chaincase and rather focus *just* on the clutching. Lightening up the primary spring, possibly lightening up the weights, and switching to a softer drive belt that doesn't slip as much can probably help you increase your mileage. Also, reduce the tension on the secondary as much as you can without causing excess belt slippage (detectable by heat), maybe going with a pink or silver secondary spring instead of the stock white.

If you want to go for performance or increase your ability to power out of deep snow, then you might be inclined to lower the gearing first.

 

[BubbaGoFast]

Thanks for the info. The reason I go with a straighter chain is for durability I know Yamaha's are very dependable and durable but we (the group I ride with) have been known to ride hard which is fine but when you hit the extremely rough trails you know big moguls. If you still crank through them chains have snapped before, and at higher speeds for the condition. It either locks up track and sends you crashing (happened to my brother) or blows the case to smitherines which happened to me. And I check my chain tensioner about every 500 miles. On another note thanks for the gas mileage suggestions I will check into clutching (I've always had someone do it for me so now I will research so I can learn myself) but I am glad you guys set me straight on mileage cuz performance is more important to me I guess I can't have the best of both worlds. I suppose if distance on a tank of gas becomes more of a problem then I'll just get a tour buddy.
P.S. My brother said to gear it back down and clutch it just like you said LB.

 

[LazyBastard]

Ah ha. Chain durability is best achieved by using bigger gears, both on top and on bottom. The bigger the drive (top) gear, the lower the torque on the chain. The bigger the driven (lower) gear, the higher the torque on the driveshaft. Upsize as much as you can and you can maintain the same gear ratio, but reduce torque on the chain. This is also more efficient in terms of the dynamics of the chaincase, and can get you *marginally* improved performance and fuel mileage. I say marginal because it is doubtful that you would be able to detect it. If you see my sig, you can see that I'm geared 23/42. Stock was 24/38, and I could have gone with a 20 or 21 on top of the stock 38 for a similar ratio, but decided on the 42 in order to keep the torque down on the chain.

Note that the 42 bottom with reverse is a $150 aftermarket part, plus it required a 72L chain and slight lathing of the teeth of the reverse drive sprocket.

 

[BubbaGoFast]

Awesome posts. I will probably go to 24/40 that way I don't have to turn down the teeth of the reverse drive sprocket and would be tons more expensive due to the fact that I only have the 22,23,24 top gears and 38,39 bottom 68,70 length chains but to buy a 25, 42 tooth and 72 or 74 length chain (because the gearing would be lower so to achieve gearing that I would like I'd need a 25/42 probably need 74 link chain) would just be too much for me to justify with a stock sled. Well it's stock now at least. See normally I buy a new sled every 2 years but not this time, I'll keep er for a little while longer not sure how long?

Probably should of never changed my gearing anyways except to 24/40 rather than messing around and causing myself a lot of headaches, cuz I didn't understand what I was doing anyways.

 

[Randy J Beyer]

Bubba why you wanna go fast ? Just kidding !!!!

Welcome to the best site ! Lazy bastard is the site
gear head with good facts and wont steer you wrong !

Also prefer Large Lightweight gears that are strong
with straighter chain if possible?

Lazy Bastard what was the gear ratio of Marv-Jorganson world
record setting run of 192 mph on ice ? Anyone know the answer ?

 

[LazyBastard]

Lazy Bastard what was the gear ratio of Marv-Jorganson world
record setting run of 192 mph on ice ? Anyone know the answer ?

You got me...

 

[fourload]

Close to 1 to 1 I bet. (Top and bottom sprocket the same.)

 

[Charged RTX]

I would go 23/39 very good all around ratio and free!

 

[SharkAttak]

so what's the best gearing for quickness and top speed, the stock gearing?

 

[Charged RTX]

23/38 if you are on ice and fairly stock. If you are on snow 22/38.

 

[LazyBastard]

Depends on how much traction you have and whether you are looking for bottom end or top end. You can't gear "for quickness and top speed", you can gear for "quickness", you can gear for "top speed", or you can compromise and gear for neither. Note that top speed requires the power first, gearing second. You can always add "quickness" by gearing lower, IF your traction supports it. If you are looking for top speed, you can gear stock or 1:1 and it won't make any difference unless you add enough power to get you there. In stock form, there isn't nearly enough power (needs an extra 50 or so hp) to get you to the top of stock gearing. Drop the equivalent of a couple teeth on top and you can go just as fast. Overdrive and drop the equivalent of 3 teeth on top like I did. If you don't have enough traction though, gearing that low will make you just sit there and spin. Don't forget to reclutch when you regear, otherwise you'll be disappointed.