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Thread: Honda CB 125 single mods

  1. #1
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    Honda CB 125 single mods

    My Son has a box of 125 parts... GL 145 front end and a SL125 motor, chassis is a CB 125s.
    We are going to build this up from scratch.
    I have a flat top 60mm piston/sleeve kit and a few( bugger all really) clues....what mods can be done to Honda 125's....?
    Any input appreciated...this is the school holiday project....after we finish the 1776 Kombi motor....

    So far....I'm thinking of:
    Overcoming the head bearing problem..Looks sleevable....
    somehow making it batteryless.
    Upping the compression....not much meat there...thin copper head gasket..?
    Bronze swing arm bushes.
    Rearsets off the swingarm.
    The frame looks a bit spindly...bracing...?
    DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.

  2. #2
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    13th April 2009 - 22:30
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    You can get them as quick as a hot FXR but it needs a few mods.

    http://www.youtube.com/watch?v=PsEFKYULNDc

    See www.marshland.co.nz for contract details.
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  3. #3
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    17th February 2008 - 17:10
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    If you are serious you will talk to John Conner
    he ran the fun day (I think)
    knows all there is to know about these honda cb buckets (you guys from wellington christchurch are just to far away and havent been doing it as long or as well sorry)

    also he has spares and spares and is a realy nice guy

    just ask everyone with a fast bucket at Mt Wellington (most have used his dyno)
    "Instructions are just the manufacturers opinion on how to install it" Tim Taylor of "Tool Time"
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  4. #4
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    12th February 2004 - 10:29
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    The CB singles would run the cam bearing if there was an oiling problem. The cure was to machine the head and fit a roller bearing. Used to be fairly common. Pete Sales at Total Motorcycles may be able to help you out with who can do a good job of it. I'd just build it up and get it running well. Decide on exactly what you want from your initial build and go for it. Worry about the mods AFTER you have it all running and you have raced it a few times. Chances are you will discover something really really needs improving rather than what you might be thinking of now. As suggested John Connor may be someone to approach. He is in the process of building a CB single right now.

  5. #5
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    Cheers Guys, will probably put it together as suggested and see if it runs.

    I have my wifes old one but its probably a bit nice to bucket.
    She gave to a friend about 20 years ago and he went a bit mad on it....then went overseas and gave it back.
    Last ran about 10 years ago.
    Came with lots of spares...hence decision to go with Honda.
    I had a SL125 that I fitted a XR200 motor too....ah memories....

    http://www.kiwibiker.co.nz/forums/al...ictureid=35516
    DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.

  6. #6
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    Quote Originally Posted by Voltaire View Post
    My Son has a box of 125 parts... GL 145 front end and a SL125 motor, chassis is a CB 125s.
    We are going to build this up from scratch.
    I have a flat top 60mm piston/sleeve kit and a few( bugger all really) clues....what mods can be done to Honda 125's....?
    Any input appreciated...this is the school holiday project....after we finish the 1776 Kombi motor....

    So far....I'm thinking of:
    Overcoming the head bearing problem..Looks sleevable....
    somehow making it batteryless.
    Upping the compression....not much meat there...thin copper head gasket..?
    Bronze swing arm bushes.
    Rearsets off the swingarm.
    The frame looks a bit spindly...bracing...?
    Sorry if the motor isn't as described?

    Quote Originally Posted by Voltaire View Post
    Cheers Guys, will probably put it together as suggested and see if it runs.

    I have my wifes old one but its probably a bit nice to bucket.
    She gave to a friend about 20 years ago and he went a bit mad on it....then went overseas and gave it back.
    Last ran about 10 years ago.
    Came with lots of spares...hence decision to go with Honda.
    I had a SL125 that I fitted a XR200 motor too....ah memories....

    http://www.kiwibiker.co.nz/forums/al...ictureid=35516
    Like I said, should only need the timing reset and it'll go

  7. #7
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    Quote Originally Posted by wbks View Post
    Sorry if the motor isn't as described?

    Like I said, should only need the timing reset and it'll go
    I haven't even looked at it yet, I was refering to some spare parts I had.
    The early one piece head flog out the ' bearing' surface at the front of the cam.
    DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.

  8. #8
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    Quote Originally Posted by Voltaire View Post
    Cheers Guys, will probably put it together as suggested and see if it runs.
    I've been told getting the Valve timing on these correct makes a huge difference.
    Heinz Varieties

  9. #9
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    Quote Originally Posted by koba View Post
    I've been told getting the Valve timing on these correct makes a huge difference.
    lol....... Where'd ya hear that?

  10. #10
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    just get a gsxr1000 then u will be ok

    MFSC lives on!

  11. #11
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    Some good Honda single related info here, it's XR200 orientated but may be useful http://vincentcrabtree.co.uk/XR200.aspx
    "If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."


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