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Thread: 20 tooth front sprocket on '16 SR400

  1. #1
    Junior Member
    Join Date
    May 2017
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    Downeast Maine
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    2

    20 tooth front sprocket on '16 SR400

    Has anybody bumped the front sprocket on a SR400 up to 20 tooth?

    Looking to drop engine RPM at highway speeds to help cut the vibration a little.

  2. #2
    Junior Member
    Join Date
    Mar 2017
    Location
    Sydney, AUS
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    10
    That's one bigger than standard. Yes i did do it, there was a small change, nothing drastic.
    No mods were required to the casings, even the standard chain still fit.
    For my mind, it mostly made 1st gear better as standard is too short. Highway improvement was negligible.

    Also changed to a 51T on the rear later, now that's nice cruising, beware of big hills though.

  3. #3
    Yes simple change and they're available...

    SR
    ...'Any unnecessary items on the bike, that it doesn't really need, shouldn't be there!'. (Café racers creed). SR..

  4. #4
    I put one during breakup period, bike had around 500 miles on it, gearing felt too short for my taste, been driving it so ever since and don't plan to go back.
    I'm rarely driving over 65 mph, but almost always when have a chance around 60 in 5th, so it fits perfectly to my style.
    To me is important that it drops rpm for 250-300 at given speed, seems not much but makes difference on long runs.

  5. #5
    SRMario wrote: it drops rpm for 250-300 at given speed, seems not much but makes difference on long runs

    May not seem much, as you say, but is around 4 or 5 revs per second: A useful reduction.
    If coupled with a 55 rear sprocket as well, this makes for nice cruising, (4,000 revs at 60mph) and you can still get up hills.
    Steve

    Edit: Also got rid of bad vibes in 3rd gear!
    Last edited by SteveP; 06-14-2017 at 03:30 PM. Reason: Additional info

  6. #6
    Quote Originally Posted by SteveP View Post
    SRMario wrote: it drops rpm for 250-300 at given speed, seems not much but makes difference on long runs

    May not seem much, as you say, but is around 4 or 5 revs per second: A useful reduction.
    If coupled with a 55 rear sprocket as well, this makes for nice cruising, (4,000 revs at 60mph) and you can still get up hills.
    Steve

    Edit: Also got rid of bad vibes in 3rd gear!
    That would be even nicer combination Steve.
    If you've tried it, please say how the 4th responds with 20/55,
    is it useful enough for overtaking and what max speed you get in 4th at 6000 rpm?

  7. #7
    If PHPaul doesn't mind me replying to SRMario on his thread:

    SRMario wrote: please say how the 4th responds with 20/55,
    is it useful enough for overtaking and what max speed you get in 4th at 6000 rpm?


    It's easy to do 50mph and more in 4th with 20/55. Very good for overtaking.
    I never rev to 6,000rpm!
    Steve

    Edit: Does 40mph at 3000 revs in 4th gear. Equates to 80mph at 6000 revs!!
    Last edited by SteveP; 06-17-2017 at 07:03 AM. Reason: Additional Info

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