Stock DS...20x11x9 rear tires, 16 tooth front and 40 tooth rear sprockets. Stock REV limit is 7700.

 

Using the above post information, a stock DS650 (once again ignoring drag) gives a top speed of 75.41mph. Now, change the tires to 22" and the speed goes up to 82.95 provided the DS can pull the larger tires.

 

I thought something sounded fishy about those 100MPH claims from the "stock" DS that won Baja. So, with 17/42 gearing at 8500RPM working to 92 MPH, and my dyno charts showing 38 HP[and dropping] at the same 8500RPM for a DS with a pipe and ignition box, how did they get the power/rpm to run another 7-8MPH faster? The way my chart shows power dropping at about 4 HP per 500 RPM, I wonder what power level/RPM they would have been at to pull 100MPH?

If I'm guessing correct, they would have to have been running around 9173RPM.? Thats around 33HP if the power dropped off at the same rate[I stopped the dyno run at 8500RPM because it was already well past peak]. By the way, it would be around 22FT/LBS of torque at that RPM as well.

 

I don't think a DS-650 (or Raptor or Banshee for that matter) will pull high enough gearing to hit 100 MPH or even 90 MPH stock. Maybe with special low rolling resistance tires and cut fenders or other aerodynamic tricks but certainly not stock. With stock gearing on my modified Banshee I could hit 82 MPH and with a 1 tooth larger counter sprocket only bumped it up to 84 MPH.

 

from past experiance, any thing over 85-90mph on rough terrain or even semi-rough terrain and YOU WILL SWEAR YOUR DOING A 100mph!
those speeds are freaky especially with a twitchy front end , the baja team claimed to hit those speeds on long flat deserted asphalt stretches, I think 90 was probably tops.

 

LT5001987...please feel free to spread the knowledge...most of us enjoy informative posts.

It would be nice to have wind drag #'s for a sport quad at 60MPH, 70MPH, and 80MPH. I bet the drag would almost double from 60 to 80 MPH.

I have a spreadsheet I have made up (straightforward...no frictional/wind losses). If anyone wants to mess around with it....just ask.

 

Garyc660r, you got it. I wish I could find a reference but, essentially, wind resistance is not linear at all; it's more of a exponential progression.

 

<< If roostina10lbbike is going to get snotty about it and play &quot;who's more macho&quot; then I bow out as I don't play that. All I come to these forums for is to share information and learn a thing or two. If no one wants my input than I won't come anymore. >>



Very well said. I think that everyone here appreciates your input, and your mature attitude.

roostina10lbbike, maybe you will think twice next time you post that way. You never know when you're smart remarks will come back and bite you in the &quot;you know what&quot;.

-Josh

 

If anyone is interseted, I put a gearing calculator(mph) on my web site already setup with drive ratios for the ds650.

 

Its hard to figure TIRE GROWTH.It will not show it on a dyno ether,the bike is straped down.