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Thread: swapping primary gears xb12 to xb9

  1. #1
    I am looking for a little more low end grunt from my xb12r. I understand swapping the engine sprocket in the primary from the xb12 to one of an xb9 can make a considerable difference. This will be a change from 38 teeth to 34. Has anyone here done this? And, what did you discover?

  2. #2
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    Free bump for curiosity sake

  3. #3

  4. #4
    Senior Member 50dro's Avatar
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    As 09 showed...lots of threads on this. I just did it on mine and LOVE IT!!! You'll lose some top end but it's a blast everywhere else! :D

  5. #5
    Is it just the sprocket that's replaced, or do you have to replace the chain also?

  6. #6
    Senior Member 50dro's Avatar
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    both

  7. #7
    Yes, I found Artur's thread, after some digging, about the swap. I hopped on the Buell wagon late. There is a wealth of info out there but sometimes its difficult to find. I don't mind losing a little top end for a bit more grunt. My biggest concerns were how much top end I would lose for a gain in acceleration and front wheel lift. Punching the numbers my bike runs 80 mph at about 4k. This gives me a theoretical top speed of about 136 mph at 6800 rpm. Swapping to an XB9 sprocket and chain seems like approximately 11% change in gearing. Which should net about 4500 rpm at 80 mph. Top speed at 6800 rpm should be about 120 mph.
    I am just trying to verify my numbers are on the right track. I would like to hear from others who have done the swap. Thanks 50dro!
    I like to wheelie and ride the mountains. Riding the 421 "the Snake" this weekend with a friend who owns an 1100 Monster I determined my xb12r is too civil. I want a lot more aggressive asphalt chewing torque monster. So, those who have changed engine sprockets, was this a change you were happy with or would you just prefer to undo the modification?
    Thanks

  8. #8
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    Damn. Guess I won't be doing this one. Sounds rough 4500 at 80 is a no go that shifts the power band way down. I like my 134 top end

  9. #9
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    I did it and loved it! If you cruise in the city you will enjoy it. Really pulls that front wheel up! LOL If you are a highway cruiser or going on long trips the higher rpms will be a drag. All depends on the riding you do. I don't ride fast so top end is of no concern to me. But I sure do get there quicker! LOL I hate riding on the expressway so I enjoy the swap but if you cruise the expressway I would think twice about it.

  10. #10
    Senior Member 50dro's Avatar
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    Top speed at 6800 rpm should be about 120 mph.
    Confirmed! :p I think you'll like it a lot for the type of riding you say you enjoy.



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