Primary Gearing Swap

[Metzman]

I am curious if anyone has tried putting the XB12 38 tooth primary crank pulley in an XB9? I know this works the other way around, putting the XB9 34 tooth pulley on an XB12, which will give better acceleration at the expense of top speed. I realize I will also need the longer XB12 primary chain in addition to the crank sprocket.

I don't hot dog my XB9, so losing a little acceleration isn't a problem, and dropping the cruising RPM by approx. 400 to 500 RPM would give better highway comfort and efficiency.

I am seriously considering the swap, but wanted input from someone who has tried it first if available? Does it just turn the bike into a dog, or is it OK and still fun to ride?

My Buell is an all stock 2006 XB9R. I feel there is no lack of torque for the taller primary gearing, so it seems like a reasonable change. On a related note, how is the speedometer driven, from the transmission or from a wheel, or?

Thanks for the input...Metz

[konarider94]

Speedometer is off of the transmission output so you will be fine. Can't comment on performance. I have the 9 gearing in my 12 engine. It was a pretty noticable change so I imagine you would notice the opposite as well.

[squidbuellie]

I have done it to 3-4 xb9's it basically stretchs out your gearing by about 600rpms and gives you better gas mileage.
You still will be able to pull 1st gear wheelies with rolling on/off the throttle.
And if you want to do the swap? I have a couple of xb12 primary's

[Metzman]

Cool, thanks for the info! I will get back to you on the parts...Metz

[Metzman]

Does anyone know what the difference is between the primary sprocket/flywheel on the 03-07's is versus the 08 and up? Does the 08 and up work on the 03-07 motors?

Thanks...Metz

[UMDterp13]

I texted you back with links to that info