Anyone running 13/48 gearing?

Need to gear to get over 70mph in the open desert, what speed can I expect with 13/48?  I max out at about 64 mph with 13/50

Need to gear to get over 70mph in the open desert, what speed can I expect with 13/48? I max out at about 64 mph with 13/50

you'd be going about 60. Smaller sprockets = quicker acc. But lower top speed. Larger tooth sprockets = higher top speed but slower acceleration,

Try 13/52

Not sure about that YZF, here is statement from motosport.com:

 

For Faster Top Speed (more top end)

  • Use a larger front sprocket or smaller rear sprocket. Again, changing the front makes a larger impact to your gearing than changing the rear.
  • Creates a higher gearing ratio. Higher gearing ratios work well in high speed situations such as desert riding, sandy motocross type tracks or anywhere that doesn’t have very many tight turns.

Gear_Ratio.jpeg

Edited by jimmyh

Not sure about that YZF, here is statement from motosport.com:

For Faster Top Speed (more top end)

  • Use a larger front sprocket or smaller rear sprocket. Again, changing the front makes a larger impact to your gearing than changing the rear.
  • Creates a higher gearing ratio. Higher gearing ratios work well in high speed situations such as desert riding, sandy motocross type tracks or anywhere that doesn’t have very many tight turns.
Gear_Ratio.jpeg
the front sprocket is correct but that corresponds with the rear, lower gearing means better acc. And more torque higher means more top end.

Right so 13/52 as you recommend would have lower top speed. It's math

Right so 13/52 as you recommend would have lower top speed. It's math

no it should have a higher top speed.

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Right so 13/52 as you recommend would have lower top speed. It's math

ok also why does WR250F stock hit 90 (geared 13/52) and a stock YZ250F hit 65 (geared 13/48) and the YZF hits that A LOT faster than the WRF?

Well I have two ways of thinking about this and I can't figure it out... But yeah nvm. You were right but still the WRF and YZF stats don't make sense... Unless, does the WRF have six gears?

If you see the chart I posted, you can see all the combos. Higher FDR=lower top speed. Just like the diff on a car.

Back to KLX world, anyone have gearing suggestions for more top end?

Smaller drive (front) sprocket = more torque but less top speed.

Smaller driven (rear) sprocket = less torque but more top speed.

Tires also play a part. A taller rear tire = more top speed but less torque.

I run 12/50 and top out around 72-75 mph. That is with a 120/100-18 rear tire.

A 13/50 should yield nearly 75-80 mph if your bike is running like it should.

Are you running out of power or engine rpm? The gearing may not be what is holding you back.

But the simple answer to your question is that a 13/48 or 14/50 gearing combo should put you above 80 mph.

Jimmy, i would run 14/48 if i were you. You could even get away with just the 14t sprocket...its a much easier swap than a 6 bolt rear sprocket every time you re-gear. An extra tooth up front is equal to going down roughly 3.5 teeth out back. Its also much cheaper to swap out the front rather than spending up to 4x as much for a quality rear sprocket.

Edited by KLX450-DIRK

I think I'll go full out and do the 14/48 and see if I can handle this long gears. If it it too tall I can swap back to the 50 or swap back to the 13 with the 48. I run a pretty meaty 120/80-19 tire, my chain is maxed to get the tire to fit. Smaller rear sprocket would give me some room.

Smaller drive (front) sprocket = more torque but less top speed.

Smaller driven (rear) sprocket = less torque but more top speed.

Tires also play a part. A taller rear tire = more top speed but less torque.

I run 12/50 and top out around 72-75 mph. That is with a 120/100-18 rear tire.

A 13/50 should yield nearly 75-80 mph if your bike is running like it should.

Are you running out of power or engine rpm? The gearing may not be what is holding you back.

But the simple answer to your question is that a 13/48 or 14/50 gearing combo should put you above 80 mph.

what RPM are you at hitting 80mph on stock gears? 13/50

14/50 with a 140/80/18 tire and I max out at about 84 on the GPS.  I would run 14/45 in the Baja.  It would be good on mileage and still make good power through the soft stuff.

I'm planning on prerunning the 1000, not race this year. 1.130 miles with a buddy and a chase truck just for fun. Just want to finish it and consider racing another year.

Near 10,000 rpm's.

With my current setup I am running out of engine rpm's, not power.

I agree with the previous post that if you want to run 80 for an extended period if time then somewhere between 14/47 to 14/45 would be the better choice.

Near 10,000 rpm's.

With my current setup I am running out of engine rpm's, not power.

I agree with the previous post that if you want to run 80 for an extended period if time then somewhere between 14/47 to 14/45 would be the better choice.

I guess that makes sense, I'm hitting about 68 at 8,500 on the beach. I have my Trail Tech Vapor lighting up at 8,000 and I am pretty easy on my engine. Besides riding in Baja, I run 12/51 here in my local mountains, mostly riding under 50mph.

 

Need to gear to get over 70mph in the open desert, what speed can I expect with 13/48?  I max out at about 64 mph with 13/50

 

I agree with Dirk or Crazy Al for desert racing, but the original question is a simple math problem who's answer is 66.666mph.

Somewhere around here I did a spreadsheet going from crank through all the gear reductions to the rear wheel to see MPH at any RPM, any gearing, and any tire size. Pretty cool.

Wiely, using the chart I put up earlier: stock is 13/50=3.85  I am going to 14/45=3.21

 

This is a 16.6% increase.....so theoretically 16.6% more speed on each gear.....correct?

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