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    Default sprockets and rotor math shit

    is there a 'standard' sprocket/rotor combination for an 883?
    bike came with 23/48 (it's on 02, but has chain conversion). i always felt like it doesn't have enough top end, but maybe I'm imagining things. up to 50 or 60 it runs great, but to push it faster it seems like the engine doesn't want to do it. maybe thats just how they run though?

    what's everyone else running? what should i expect from this set up?

  2. #2
    Bud
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    Did you do the conversion?
    Do you have a factory manual for your bike? I don't have one for it but a good starting point is to find out what it had from stock.

    Without that information I have to guess and there are too many variables for me to do that.

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    Quote Originally Posted by rus View Post
    is there a 'standard' sprocket/rotor combination for an 883?
    bike came with 23/48 (it's on 02, but has chain conversion). i always felt like it doesn't have enough top end, but maybe I'm imagining things. up to 50 or 60 it runs great, but to push it faster it seems like the engine doesn't want to do it. maybe thats just how they run though?

    what's everyone else running? what should i expect from this set up?


    I'm running a 22/48 from Led Sled in my 883.

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    bud

    it had belt stock, so i don't know how to convert that into a chain equation, or if the manual would even list those numbers.

    i suppose it has less to do with the particular motor/bike and more just the ratio of the two gears together. i know higher/lower on either one will change low end or high end, i just don't know what the 'standard' is, or what i should expect with this set up.

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    Quote Originally Posted by rus View Post
    bud

    it had belt stock, so i don't know how to convert that into a chain equation, or if the manual would even list those numbers.
    Here's what I've learned trying to figure out what sprockets I need.

    • Divide rear tooth #, by the front tooth # = Sprocket Ratio.
    • Increased ratio means you trade off low end power for lower RPM's at higher speeds.
    • Decreased ratio means you trade off higher speeds for more torque at lower speeds.


    Your bike (stock with the belt) had 61 rear teeth and 27 front.
    [61/27=2.25] Front sprocket does 2.25 revolutions compared to 1 in the rear.

    Now with chain drive, 48 rear and 23 front.
    (48/23=2.08) Front sprocket does 2.08 revolutions compared to 1 in the rear.

    Now compare the two - From stock, to what you have now.
    ((2.25/2.08) -1 * 100) = 8.17% increase in sprocket ratio.




    I think the PO went a little too far with the 23T, you're probably at really low RPM's at 60MPH but your bike just doesn't have the torque left to combat wind resistance go any faster.

    The closest sprocket ratio to what the belt had would be 48 Rear and 21 Front which is what the chain drive 883's came with.
    (48/21=2.28)


    I only know this because I recently put an Ironhead rear drum (51 Tooth sprocket) on my 91 Evo Sporty and need to find a 23T front sprocket to get my old ratio back. I'd trade ya but I'm thinking your front sprocket my be different than mine.. If they're the same I'd be down for sure.

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    thank you. math is not my strong suit.

    that would make sense. from what i recall (its been torn down for a bit) it doesn't feel like it's revving super high, it just feels like it doesn't want to go any faster. like the engine is maxed out or something.

    it's an offset sprocket, which i doubt is what you're looking for.

    if i can borrow your math for another second... what tooth could i switch to in the rear to bring it back closer to normal? pulling the front sprocket looks like it would be a pain in the ass, plus I'm pretty sure rear would be cheaper. i'd trade you, but i highly doubt you need an offset sprocket.

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    Thanks anyway, I wasn't sure if you had an offset sprocket or not.

    A 51T rear sprocket would be what you're looking for then. 51/23=2.21 (closest ratio compared to belt's 2.25). You may need to add a link or two to your chain depending on how tight it is now with the bigger rear sprocket.

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    awesome dude. thank you much.

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    never mind, asked google instead. thanks again.
    Last edited by rus; 01-14-2012 at 3:17 PM.

  10. #10
    Bud
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    [QUOTE=rus;253703]thank you. math is not my strong suit.

    that would make sense. from what i recall (its been torn down for a bit) it doesn't feel like it's revving super high, it just feels like it doesn't want to go any faster. like the engine is maxed out or something. QUOTE]

    When you say it doesn't want to go any faster do you mean it will gain MPH but slowly?

    Do you have a tach on your bike? We need to know what MPH your running out of power and at what RPM...

    I know an 02 883 should be able to run far past 60 MPH, unless there is a mechanical reason it won't. At some point all bikes will run out of throw your ass back power but they will continue to accelerate, your bike should be capable of running 90+MPH.

    Here are some links that may help you understand gearing;
    http://www.gearingcommander.com/
    http://www.gearingcommander.com/
    http://en.wikipedia.org/wiki/Mechanical_advantage
    Last edited by Bud; 01-14-2012 at 3:42 PM. Reason: Forgot Links

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    no tach.
    it runs great up till about 50-55, then it just feels like it sorta 'tops out'. you can get it faster, but you've gotta stay on the throttle hard and it'll slooooowly gain speed past that point.

    I've always suspected it was an issue of the ratio, just never got around to counting teeth to run it past anyone. looking on ebay for sprockets. gotta measure the inner diameter of the one Im currently running to see what i need to replace it with. should be a pretty cheap fix.

    appreciate y'all.

  12. #12
    Bud
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    Go to my last post and check out the links I added.

    I hit reply before I added the links so you may have missed them.

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    dude, thats so much more science than my feeble artistic mind can comprehend.

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    anyone know what years had rear sprockets with 2 1/8" inner diameter?

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    Chrome Flat Rear Sprockets:
    "- Available for 1973-'99 and 2000-up models in 48 and 51 tooth counts." Maybe give these guys a call to make sure they fit your bike?

    http://www.bitterendchoppers.com/DrivelineOffsets.html

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    yeah, I've found several places that sell them, but no one seems to list the ID. i feel like an asshole calling a shop and asking them about their $80 sprocket when i can find them on ebay for $20 all day long.

    i've googled the shit out of this question, but it seems that no one knows. i'm sure it's common knowledge to someone, just no one i've found yet.

  17. #17
    Bud
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    Quote Originally Posted by rus View Post
    yeah, I've found several places that sell them, but no one seems to list the ID. i feel like an asshole calling a shop and asking them about their $80 sprocket when i can find them on ebay for $20 all day long.

    i've googled the shit out of this question, but it seems that no one knows. i'm sure it's common knowledge to someone, just no one i've found yet.
    I have ordered three spacers for my 96 from Vulcan Engineering and all three times they sent me the wrong ID.
    I finally just put the last fucker on and ran it, it works fine. Got no idea why...

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