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Cb400 sprockets

Discussion in 'Modifications and Projects' started by vdog23, Apr 25, 2014.

  1. Hi all,

    I have a 2008 cb400 and I'm thinking about changing my sprockets to reduce the revs at highway speeds.

    I live in the country and 80% of the roads I travel on are 110km/ph and at that speed the bike I reving to 7000rpm which is where vtec roughly engages.

    So I would like to reduce these revs so that the bike is less strained at these speeds and not constancely on and off the vtec.

    I also love the response of the bike so I don't want to hurt that to much if possible.

    So if anybody has any experience with changing sprockets and achieving these sort of results please let me know what you changed and how it changed your bike.

    Thanks for reading and I look forward to any help anyone can give me.

    • Informative Informative x 1
  2. Cheers thanks for the link
  3. Without knowing the specific details of your bike, I would suggest that a quick, easy and inexpensive mod that might achieve what you are looking for would be to simply go up one tooth on the front sprocket. You would likely not have to change the chain length at all, simply adjust chain tension to suit, and front sprockets are cheaper than rears.

    According to the website http://www.gearingcommander.com/ referred to earlier, this one change would drop your revs by 6.25%.

    Hope this helps,

  4. The Wife's TU250x will go from T15 sprocket to a T16 sprocket in the front next week
    part 25$, labour $50.

    Simply it Will turn 5th Gear into 4th gear and give her a better top end for a 250cc and much quieter.
    and 1st 2nd and 3rd gear will now be usable :)

    Plenty of youtube videos maybe there is one for your bike.. good luck
  5. Thanks for the feed back everyone.

    I would been interested to know the official results that you get from the tu250x when you get it done nickvt400.
  6. The TU250X is booked in next tuesday for Sprocket change and service
    I will let you know what the wife thinks of it when its done..
    TU250x is really geared badly for highway.

    Remember that your Speedo may be effected and may show you going faster than you really are
    depends if speedo works on front wheel or gearbox.

    youtube for TU250x t15-> T16
  7. Update.
    Wife loves the new sprocket gives the bike more oomff
    Better top end and gear changes etc
  8. Hi there new here and just trying to become part of the community.
    I found a big write up on the CB400 on the Singaporebikes site.
    Please check with your mechanic that the sizes are the same for Australia but here is a Copy and Paste bellow.

    If you just made the adjustment by 1 size surely it wont affect the acceleration too much?


    Stock chain setup for CB400 is 525 chain/sprocket.

    Front15 Rear44 ( For Revo ).
    Bigger rear or smaller front sproc for pick up.
    Smaller rear or bigger front for top end/expressway cruising.
    Changing rear sproc is better because front sproc affects the ratio a lot.
    Smaller front sproc or bigger rear sprocket results in better acceleration but lousy top end.
    ( Good for urban/city riding )
    Bigger front sproc or smaller rear sproc results in better top end but slower acceleration.
    ( Good for touring or long journey trips, good for daily expressway users )
    ( This setup saves fuel as engine will not be that stress compared to urban setup when travelling on expressway)
  9. Im new here. I just got the tu250x myself and I'd like to know if there's any places online or around the gold coast south Brisbane area or online that sell aftermarket parts such a exhausts' handle bars, grips, foot rests and engine parts for the tu250x. I'm new to bikes. Moved from driving an 1993 r33 series 2 gtr.
  10. Responding to an old post but thought i would share my recent experience.
    My 2010 Honda CB 400 was always a bit tiresome on highway trips with the revs high in the 110/120 k range in 6th.
    A bit of research seemed to suggest going up a tooth or 2 on the front and down about 4 teeth on the rear.
    The original sprockets are 15/44.
    I opted for a 17 on the front but unfortunately room around the front casing wont allow this size.
    I went for a 16 front 40 rear.
    At the same time i fitted a new chain.
    Job was fairly straight forward with a bit of a struggle getting the back wheel back on with the brake housing locator thingy.
    Bike is transformed with much more relaxed cruising.
    Seems to still get off the line quick and all gears have an extended range.
    Speedo is about 15 / 17 % slow.
    Have checked it with a GPS for now and marked 50 to 110 with small white paint pen dots on the speedo glass.

    Have to get the speedo recalibrated some time.

    Anyone know how I can get this done ?
  11. There is a company here in Melbourne called Ringwood Speedometer Service, 693 Whitehorse Rd, Mitcham VIC 3132, ph 03 9874 2260
    Long way from Perth I know, but if there is no local to you equivalent they might be able to sort you out.
  12. You can buy a speedo healer for the cb400 simple plug and play.
    Easy to program .
  13. More better than my idea.
  14. Hi Mate
    Just bought a 95 CB400SF and the first thing i noticed was high RPM at highways, searched and came across your post

    just wondering how is your conversion of 16/40 from original 14/44 doing, what is the RPM at lets say 80KMPH, how is the power output at top gear, how does it perform overall?