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Project The Mistress. BSA B31 350cc

Discussion in 'Other Projects - Other Bikes (non 250's)' started by Evo, Apr 9, 2017.

  1. Evo

    Evo Well-Known Member

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    IMG_1561.JPG IMG_1608.JPG IMG_1625.JPG IMG_1755.PNG I have a new mistress in my life. A 1950 BSA B31

    Saw this on gumtree late November last year and knew I had to have it. So after waiting for it to be trucked over to Adelaide and arriving 2 days after I left on a 6week overseas trip ( i swear I thought about this bike everyday we were away) I finally saw it for the first time late January.

    It was a big risk buying an unseen bike but was more than happy with it and had been given a very realistic discription by the seller.

    Long story short I did the following.
    Gearbox oil
    Clean out oil tank, new oil (3 changes)
    Primary drive case gasket and oil
    Clean the chain and oil
    Cleaned the carby. New seals and gaskets
    New battery
    Checked brakes
    New fork boots
    New spark plug
    Fresh fuel

    After about 5 kicks she came to life. So much relief.

    Got rego for it the other day and took it out for its first (legal) ride yesterday with a massive smile on my face. Can't wait to take it out again

    I realise this is not the typical bike on here but I'll think I'll hang around as there is such a wealth of friendly knowledge around here.
     
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  2. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    That's awesome , congrats on buying such a cool bike
     
  3. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Brilliant mate .... always great to see old school and not made in Japan :D
     
  4. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Nice.
     
  5. risky

    risky risky

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    very nice
     
  6. Brizfox

    Brizfox Well-Known Member Premium Member Contributing Member

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    Jesus that looks good.
     
  7. Wozza

    Wozza Active Member Premium Member Contributing Member

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    Oh My that brings back some memory's :) nice bike use to love mine but had to sell her back in the early 90's :( As I could only bring one bike when I moved to S.A img040.jpg
     
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  8. Evo

    Evo Well-Known Member

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    So started to pull the engine apart for a general checkover and to remove the Magneto as it needs a referb. The more I pulled apart the more I discovered. Drilled out timing gears, ground rockers and then discovered it has been bored out to fit a Triumph T140 piston to make it a (roughly) 400cc. This would also explained the larger than stock carb its running.

    Someone has done some work to this engine in the past

    IMG_2134.JPG IMG_2135.JPG IMG_2139.JPG IMG_2140.JPG
     
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  9. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Nice, cant complain about that.
    Look's like the head has had some port work done as well, or at least the intake has, i reckon the short return's would have been cleaned up too
     
  10. Evo

    Evo Well-Known Member

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    Yea, the intake has been done but it needs a good clean up to see exactly what has been done
     
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  11. gregt

    gregt Active Member Premium Member

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    There used to be quite a few iron BSA singles active in Classic racing here. The recipe as you have it was quite common. They go quite well too.
    The big question is - what numbers are on the cams ?
     
  12. Evo

    Evo Well-Known Member

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    Yep that's the next thing to look at. Hoping the bloke who did this didn't do all of this without replacing the cams with goldie ones or the like
     
  13. tarmacsurfer

    tarmacsurfer Well-Known Member

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    I like that a lot!
     
  14. Evo

    Evo Well-Known Member

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    IMG_2738.JPG IMG_2739.JPG IMG_2740.JPG So long story short I put in new rings and she is running sweet (for now, let's hope it continues) also a new set of tyres. Took it out this arvo for a bit of a shake down.
    Did the obligatory Jetty road then espy cruised it back to Brighton (the Adelaide guys will know) all went well till i felt the battery holder hit my leg. Pulled over put a cable tie in did a U turn and fount the bolt in the middle of the road. Not bad at all considering.
    Had a massive smile on my face the whole way
     
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    Last edited: Sep 19, 2017
  15. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Nice work!
    And a top day for it too.
    You're only just down the road from me, i'm at South Brighton
     
  16. Evo

    Evo Well-Known Member

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    I'm also at south brighton. Small world

     
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  17. Mike Fulcher

    Mike Fulcher Member Premium Member Contributing Member

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    85' Yamaha SRX 250, 87' Honda VT250, 86' Suzuki NZ 250, 87' Honda CBX 250, 74' Yamaha AGR100R Racer
    An awesome old classic, these bikes can be modified very successfully for the modern classic racing scene.
    One advantage with the older cast iron cylinder heads is there is almost no restriction on how open you can enlarge the intake & exhaust ports. with modern camshaft theories its not that difficult to design your own what call scatter profile patterns, and machining up cams is not that expensive these days.
    Come on guys, whats your thoughts?
     

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