Has Anyone Mid Frame-mounted A Subaru/Mits/Honda/Tanaka Engine?

Discussion in 'Frame Mounted Engines' started by 5-7HEAVEN, Apr 24, 2010.

  1. 5-7HEAVEN

    5-7HEAVEN Guest

    With the advent of the SBP shift kit, has anyone frame-mounted any of these engines and run them through the bike's gears? Scooterguy mounts his engines a little higher in the frame. I'm thinking a little lower, nearer to the pedals.

    Midframe seems like the next combination to use. The chain length would be short, and a 5:1 gearbox would bring the gearing up to speed. High-performance expansion pipes would have more room to clear the bike's frame.

    Anyone doing this?

  2. 5-7HEAVEN

    5-7HEAVEN Guest

    It Might Be Possible.

    I've been in contact with Pablo and Jim at SBP. They MIGHT have all the parts I need to frame-mount my Mitsubishi/Tanaka/GP460 engine and run thru the gears. Jerry at Scooterguy supplied me the chainrings, freewheel, #25 chain and 5:1 gearbox. Thatsdax.com is shipping my 1/2" jackshaft axle, another vendor has my sprockets on the way. Bearings and collars are from BMP friction kit.

    Waiting for parts to arrive. School finals are next week, so I should have time after that to work on my bikes.
  3. moped-dan

    moped-dan Guest

    I've been dreaming about a setup like this.. Really looking forward to see what happens.
  4. 5-7HEAVEN

    5-7HEAVEN Guest

    I've hit a snag.:ack2:

    The #25 sprockets arrived today. They do not work with the chain that scooterguy supplied. I checked Scooterguy's website, and he uses 8mm chain and sprockets!


    My mistake. I thought scooterguy's drive was #25, but it's 8mm drive...including the gearbox sprocket, which I won't be able to use.

    I COULD fab a plate onto the SBP motor mount and run the 8mm chain directly from the 5:1 gearbox. That way, the engine will fit, but stick out as much as the scooterguy setup, only lower.

    I DID see a#25 sprocket at an online website, with 6-pinion splined-bore for the 5:1 gearbox. It's 15-teeth to match a 15t on the jackshaft. now I need to locate a 15t with 1/2" bore that'll run an 8mm chain. If I DO find that sprocket, I'll be able to use the SBP jackshaft and move the engine inward for better clearance and balance.

    If I don't utilize the #25 sprockets, jackshaft and bearings, I'll use it on my other project, which is:

    Last edited by a moderator: Apr 29, 2010
  5. 5-7HEAVEN

    5-7HEAVEN Guest

    Thanks, man. Exactly what I was looking for. Right now, I have a Tanaka 47R engine on a Scooterguy frame mount. The next design change might be to move the engine into the frame. Sadly, the engine won't fit into this bike's frame, so it'll have to be another bike, another time.
  6. no problem, have you seen this as well?


    im intrested also in a in frame mounted system that drives the crank for a robin subaru eho35

    but cant think of a gearbox, only this http://www.funbikes.co.uk/Midi_Moto_Gearbox(324).aspx
    but i dont think the reduction is sufficient.

    any chance of a drawing?

    from your mention of jackshaft i sketched this (please see attached)

    i Think ill go for something like this with a 5:1 gearbox


    dont give up

    Attached Files:

    • j.JPG
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  7. 5-7HEAVEN

    5-7HEAVEN Guest

    Looks like a sharp install. Bike might need a larger rear sprocket, though, if that's a pocketbike engine and gearbox.

    Your drawing looks very similar to Scooterguy drive kit, which is what I'm using. A 5:1 gearbox and SBP shift kit might work perfectly for you.


    JMO, along with the SBP kit, this 5:1 gearbox is the key component that makes the utility engine-frame mount possible.
    Last edited by a moderator: Jul 3, 2010
  8. yeap i think so just need to find a way of making it stealth people are pretty hostile to them where i am :(

    do you have a picture of your latest setup?

    p.s. what is a JMO?

  9. 5-7HEAVEN

    5-7HEAVEN Guest

    JMO(Just my opinion), a rackmount might be easier to conceal the engine.:detective:
  10. ocscully

    ocscully Member

    I've been riding one of the SBP 4-stroke shift kit bikes for going on 4 months now and have given some thought to also setting up another bike using the EOH35. My current set up is the Honda GXH50 with the Grubee III gearbox. This gearbox is only 3.7:1 . If what you are looking for is to mount the motor low in the frame I think that Dax's 3.25:1 Duplex Chain reduction box would be what you are looking for. (see photos) This unit would be a direct mount up to the EOH35, and the output sprocket can be for #41 chain which would be compatiable with the SBP Jackshaft sprockets/cogs. This would make for a much narrower motor package. I also think that you would have more that enough reduction using this Dax unit as well.


    Attached Files:

  11. Thanks OCscully, i checked gear ratios and i think it may just work, please tell me if im incorrect :)

    just want to check widths now on my frame :)

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  12. ocscully

    ocscully Member

    I'm assuming (perhaps incorrectly) that you are going to purchase one of SBP 4-stroke shift kits to use as the base for your set-up? I'm also assuming that you are wanting to use #41 chain (1/2" pitch)? Dax offers a 10t PTO driver (power take off) that fits the output shaft of the 3.25:1 reduction box. So using the calulator 10 in the first field and 32.5 in the second field gives you 3.25:1. then the output of the box is a 10t then 10 again in the third field which will drive a 17t driven on the left side of the jackshaft, so 17 into the forth field, this equals 1.70:1 reduction. The right side of the jackshaft has a 9t driver on it so 9 goes into the fifth field and the driven sprocket on your crankset is a 48t so 48 goes into the sixth field. this equals 5.33:1, for a over all reduction of 29.47:1 before you factor in your multi speed freewheel/cassette. I ran some #'s using the 36t to an 11-34 rear cogstack and think that the ratios might be a bit on the high side. You would probably find that using a 30t on the front chainrings to be a more suitable range. If you want to run the #'s your self just input 10 into the first field and then 294.7 into the second to get your 29.47:1 reduction then you can input any combination of front chain rings 30t, 36t into the third field and any # of cog sizes from 11t - 34t into the forth field. Leave the fifth and sixth fields at 1.

  13. Hi oc,

    i have machined a 8t sprocket for a 1" chain ( i say machine it was more like a few afternoons, "hand crafting" a sprockt with a template and angle grinder :dunce:), i already have the gb. The only thing ill be buying is http://eclipsebikes.com/chainwheel-cranks-p-1008.html (frewheel crank) and some sheet metal and hardware for the mount. if anythink im worried how it will feel? but i dont think there any calculators for that :rolleyes7:

    i think ill just "get out and ride" once its ready :)
  14. 5-7HEAVEN

    5-7HEAVEN Guest

    Still thinking about center-frame mounting either my Tanaka 47R or GP460 engine. Right now, the Tanaka is a few inches from sitting on my lap, using a medium frame and Scooterguy mount.:whistling:
  15. Garp

    Garp Member

    Yes, It can be done. Check it out.
  16. 5-7HEAVEN

    5-7HEAVEN Guest

    I like your setup. Looks like a Puch.:detective:
  17. Garp

    Garp Member

    Thanks 5=7
    My first bike was a Puch, maybe it inspired me.

    Attached Files:

  18. 5-7HEAVEN

    5-7HEAVEN Guest

    You must be doing something right, if Puch and Tomos mount their engines the same way.:idea: