Engine casing discrepancies

  • Is it normal for two casings to be different? Specifically the inlet porting? The right side case doesn’t match the left by about 8mm! It’s an old 3bn that I don’t know the history of (eBay). I’m guessing that they two different year casings.
    Is it best to match them or is it normal?..

  • Yeah, they aren't well matched out the factory are they 🤣

    There is a lip on the cases at the inlet. But they are fine everywhere else.

    I presume this was done for a reason.

  • @SpookDog it's fine from what I've heard but some file it down

  • Just to embellish a bit. These are 3BN 01 cases. I have some 3BN 03 cases that are totally different. The inlet port that ‘ups into the barrel’ doesn’t have the step, but does have a ‘flaired up step’ that I guess directs gas flow up into the barrel port. I’m just wondering how many different variations of 3BN engines there are?
    I’m guessing that the 01 & 03 numbers are the year?
    Cheers guys

  • Sorry! The ‘flaired up step’ is just above the crank. Not a step in the casing. It’s more like a spoiler or a ramp...

  • A picture says a thousand words...

    alt text

  • I agree! The bits I’m on about are internal though 😜

    How do you post upload pics from a phone. Do you still need to host the pic?

  • @SpookDog yeah you host the pic then copy the picture address then. Press the picture icon just above when you are typing a post then paste the address into the highlighted section

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