Ok, I was looking at some old posts, and I saw one about using a 17th front sprocket, and a 37 rear. I typed that in on Markynark's speed calculator, and The top speed at 8500 RPM in 5th gear is 98mph!!! is that true?

What gear ratios is everybody using, and what kind of riding do they do? I was thinking of doing the 17/37 when I get my new Baja, but will it be ok for my riding conditions? -Fast trail riding, a little mud, some drag racing, and going fast!!!

 

Oh yeah, and with that sprocket ratio, raise your rear tire height to 22in and the top speed is 105mph!!! that seems like a cheap way to go fast when you need it, then just change the sprockets when u wanna trail ride. does anybody do that?

How hard is it to change sprockets?

 

well, I went back and fooled with the calculator, and figured the speed goes up 1mph fpr every 100 rpm's. 7700rpm is 86mph, and 78--rpm is 87mph, and, well, u get the point

 

Adam - the gearing you speak of will not be ideal for trail riding, and your holeshot for dragging will suck. A stock motor with stock 20" tires couldn't pull 8500rpm in fifth gear, even if it did have an aftermarket CDI, unless it was downhill, so the top end with that tall gearing would never be reached either.
I run stock gearing for 20" radials on trails, sand paddles, dragging, you name it. I have a 17 tooth front sprocket, but didn't leave it on long. If all I did was wide open riding, maybe I'd stick with the 17 tooth front, but I think I'd rather have 22" tires and stock gearing if I rode desert all the time.

 

What he said.
I run the stock rear, a 15 up front and 22inch paddles. Slightly lower than stock but in the sand the top speed difference was negligable plus You reach it faster.
I had an old Dodge charger once that would do about 140 but it took four miles to get there. Gear for the range of speed you spend the most time in.

 

Oh, one more thing, the sprockets are not quick to change like a Honda. The countershaft sprocket has like a 30mm nut on the end of the shaft that gets torqued to an ungodly spec, like around 140ft.lbs. or something like that, and then tabs have to bent around it. Changing from one place to antoher would get old real quick....by the time you slack the chain, remove the cover and crankcase guard, unbend the tabs, change the sprocket, torque the nut, bend the tabs back (if you didn't destroy it already), put the cover and guard back on, tighten the chain, you just burnt up a good half hour. And you gotta have the tools.

 

Greg Row used 17-37 for the Baja and the top speed was over 100mph. That was with a stock motor only a pipe, 22in Bandits in the rear. I run a 17 front and the stock rear with the Bandits and put on a 15 for the Dunes!This is for Desert racing. For trail riding I think you would want a 16 front.

 

Greg Row also had a rev box on that DS, and they had to replace the clutch halfway through the race because it couldn't handle the slamming on that tall of gearing.
The 17-40 DSRide is using for desert seems more reasonable...

 

I run 16/37 in the dunes but run 17/37 with 22" tires in the desert.

The rear sprockets a pain, but the front is cake after you've done it a few times.

Oh yea, keep extra washers handy!

 

They replaced the clutch because the person riding the DS was feathering the clutch. I am the only one I know racing desert with the stock rear and no one else has had to replace a clutch. I will ask Greg about the Rev box. I was told not to use it. The DS needs to be short shifted. When you get the RPMs up the power flattens out. BMW racing and Bombardier racing both said not to increase RPMs. Best person to talk to would be TimmyBoy. He has talked to both BMW and Bomb.