Honda CB250 K4 -72 racer mods
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Honda CB250 K4 -72 racer mods

This is a discussion on Honda CB250 K4 -72 racer mods within the Vintage Motorcycle Racing forums, part of the Caferacer.net Forums category; I bought the Honda three years ago and have raced it for two seasons now. In 2015 me and my son didn't change it much, ...

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Thread: Honda CB250 K4 -72 racer mods

  1. #1
    Senior Member Mike 40M's Avatar
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    Honda CB250 K4 -72 racer mods

    I bought the Honda three years ago and have raced it for two seasons now. In 2015 me and my son didn't change it much, only changed silencers in order not to get black flag, and changed shift pattern in normal race practice. Only minor problems, had to weld a broken ignition coil bracket and weld an alloy tank leak. Improved rubbers under tank. Season ended with a problem with exhaust too low. Result nothing more than new foot peg, brake pedal and hand brake lever. Plus some frame welding. Winter spent with changing exhaust and making a GRP diaper (bellypan). Season 2016 it run well except that we got oil on our right knee, could not find out why. This winter bike will get an overhaul and some modifications. Chassi behaves well, previous owners had lengthened swingarm, reinforced swingarm mount. Modified steering stem and usual frame welding. Front disc brake works well and the rear Suzuki wheel no problem. The 30mm Mikuni VM pair perform well.
    Thought it could be wise to check the engine so it was overhauled. Fairly good condition, only one broken piston ring and a broken valve spring. The improved camchain and tensioner was in good condition. The (not the fanciest) racecam was in mint condition. Another year I might polish the rockers. Right engine cover changed to a standard one because the oil lines to an external filter didn't fit with the new exhaust. Took some time matching head and carbs to inlets and exhausts.
    We decided to change from half to full fairing, so yesterday we made new fairing brackets and fitted the fairing. As nothing ever is as easy that you expect a new tacho mount was needed. New ignition coil mounting parts had to be made.
    Except for paintwork the bike is almost raceready.
    Problem left to solve is a smart quick detachable upper T-bracket between screen sides and centre steering nut.
    Any ideas?

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    Senior Member TrialsRider's Avatar
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    Senior Member monkey's Avatar
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    Construct your fairing stay bracket with a center post that mounts to the steering head tube and extends to the front of the fairing. Next attach fairing ear stays to the center support.
    You can get fancy by making the fairing stay be a quick disconnect with a pin. Do the same for the side stays. Pull three pins and remove the fairing.

    Using the top nut gets weird because it is another thing that has to be disconnected to remove the fairing.

    matt
    Tannermatic
    jcw likes this.
    latered

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    Senior Member Mike 40M's Avatar
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    Sorry, some trouble finding any pics at all. As it was on Arctic Raceway in -15.
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    Credit picman.co.uk
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    Senior Member Mike 40M's Avatar
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    How it looks today, fairing had to wait until epoxy has cured.
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    Not weather to take it out for a proper background
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    Senior Member Mike 40M's Avatar
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    With new fairing, only numbers left and possibly some paint.
    But as an old quite successful racer said: Paint ain't fast.
    So now I'll start setting up a 350 Norton racer. That's another story....
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  8. #7
    Senior Member Mike 40M's Avatar
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    Finally got the bike out of the workshop. Son didn't approve of my no-paint approach. So he did a bit of spraying. Could not do as much with the other bikes. Painting stinks.
    Name:  with fairing right.jpg
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    Senior Member CaTacL1sm's Avatar
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    a very swedish paintjob.

    you need an Ikea sponsorship now
    jesperbc likes this.
    Quote Originally Posted by alwhite00 View Post
    Fuck all of you guys. Get into your little circle jerk and have fun. Thought this may be a pretty cool message board but damn, you guys are assholes.

  10. #9
    Senior Member Mike 40M's Avatar
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    Sadly IKEA started in a part of sweden where people are very economical. Compared to them, Scots are big spenders. No chance of sponsorship.
    First start of engine this year. Checked and a minor adjustment of ignition timing after engine rebuild. Only problem was a silencer bolt that disappeared. Next weekend first practise.

  11. #10
    Senior Member Mike 40M's Avatar
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    Did a barnfind yesterday. Found a half-forgotten CB500/4 racer. Spent half an afternoon to get it running and raceready. Now we have two bikes ready to race.
    Nice to have a barn full of might-be-useful-things.

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