ASK THE MXPERTS: Can I Gear My 2003 YZ250 Two-stroke Up By Three Teeth?

January 8, 2009
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YOU ARE GEARING IT TO THE MOON

Dear MXA,
     I’m the proud owner of an immaculate 2003 YZ250 two-stroker. I’m looking for a way to make the power a bit more manageable. The current gearing is 14/51, which is okay for tight MX tracks, but do you think 14/48 gearing would be okay, as I am 41 now and sometimes find it a bit of a handful. Would it be a good idea to use a flywheel weight in conjunction with this gearing? The bike has a new top end, Pro Circuit pipe, VHM cylinder head (with standard insert), VForce3 reed and a freshly packed silencer.
 
   
     Your plan isn’t a bad one, but you have set your sights on the Bonneville Salt Flats as opposed to a motocross track. Stock 2003 YZ250 gearing was 14/50 (which is 3.57 gear ratio). You are currently running a 14/51 (a 3.64 ratio). The 14/51 is what most 2003 YZ250 racers ran back in the day. Your plan to run a 14/48 would give you a 3.43 ratio. That is tall…very tall. You would find yourself using first gear a lot (and Yamaha increased the gap between first and second a great deal for the 2003 model–to get second gear closer to third to make the gap less between the second and third).

   If you want to make your bike easier to ride, we would suggest going no taller than a 14/49. The flywheel weight is a great idea and something that worked very well on the 2003 YZ250. If it was us, we’d try the flywheel weight first (about 8 ounces) and then gear it up in increments (you may still have your stock 50-tooth rear sprocket).

Send questions to mxa@hi-torque.com

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