Sportsman Flyer Build

Discussion in '4-Stroke Engines' started by Tom from Rubicon, Jun 6, 2016.

  1. Friday afternoon I wanted to start the rear wheel build by installing the OCC sprocket adapter.
    Only to discover that the adapter would not close. Turns out hub clamping sprocket adapters only fit on coaster brake hubs. I chose to use a free wheel and the hub flange is too large.
    Later that day Lynn (CustomMotoredBicycles.com) called to warn me about the problem. She is giving me full refund, and has a sprocket adapter that bolts to the hub using the 6 threaded holes intended for mounting a disc brake.
     

  2. bakaneko

    bakaneko Active Member

    Ah, now you can get disc brakes for the rear wheel? It will provide additional braking power though the drum brake in the front looks sturdy enough.
     
    Tom from Rubicon likes this.
  3. No my friend, that six hole hub pattern is what I need to attach the drive sprocket to. Remember, Lynn had a prototype universal disk which is not in production, at this time. Lynn in on it, so it is a matter of time. Lynn recommended drilling and rethreading 6mm. I thought that was a good idea. I didn't have a lot of confidence in the existing 5mm fastener arrangement Custom builds, are always a challenge.
    How you doing?
     
  4. bakaneko

    bakaneko Active Member

    Oh, I see. I am doing fine. The noise from my chain guide in the transmission gear box is kinda getting to me. It works great but the noise not so much. I might try something else or get steel ball bearings.
     
  5. Sorry I haven't any photos here yet, but then again I am dealing with another learning curve. My only other build is a HuaSheng 49cc powered Huffy-Davidson from a Bikeberry kit.
    This last weekend by fits and starts I disassembled an EZ-matic transmission.
    1/4" 6061 T6 plate had been purchased, so I layed out a pattern of the stock mounting plate and the power in put and power out put positions.
    Band sawed the outline, centered and drilled a 5/8" power in put hole.
    Made 4, 5/16-24 transfer screws to transfer the engines hole pattern with the engine vertical and the transmission 90 degrees horizontal. With transfer screws in the block
    Slid the mounting plate onto the transfer screws, and verified 90 degrees. Striking the plate to transfer the hole positions.
    Back out to the shop re-struck the prick marks to help a drill follow center.
    The rest was Duck Soup. Drilled and counter sink’d for flat head screws.
    Back in the house, dropped the plate on over the crankshaft. Screws all fell right in.
    Next is belt sanding to true the saw cuts and transferring the drivetrain components to be mounted up for final assy.
     
    Last edited: Jul 7, 2016
  6. Sizing up every thing, sorry there isn't a Right side view also. I'm on it MB buddy's
     

    Attached Files:

  7. Frankfort MB's

    Frankfort MB's Well-Known Member

    Sexy lookin thang ain't it???
    I always liked the drop loop frames, you can fit some crazy motor setups in them

    What kind of tires and handlebars you running?
     
  8. The weight of this new build needs to be addressed regarding tires. My wheels are Worksman 26X2.
    The choices are, Continental Retro 26X2 Cream Wire Bead or more likely Schwalbe Fat Frank 26X2.35
    Cream with wire bead.
    The Conti is $22 + shipping of $11.35
    Schwalbe on Amazon $31.18 free shipping.
    Handlebars will have to be addressed later unless I get some recommendations to consider.
     
    Last edited: Jun 29, 2016
  9. Frankfort MB's

    Frankfort MB's Well-Known Member

    If your going for the board track racer then look at 60's model female bike handlebars i think they look good for that low and close look:)
     
    Tom from Rubicon likes this.
  10. Frankfort MB's
    My hopeful design, is an upright sitting stance. To reflect the early style road motorcycles when they were still pedal started. This is a labor of love and a work in progress. I finally made the blank 1/4" steel disk that will use the existing disk brake mounting holes that were M5X.6 and are going to be resized M6 x 1 to increase strength. Transmitting engine power to the rear wheel via 56T sprocket. To satisfy my strength requirements a steel band may have to be heated and allowed to shrink around that part of the hub.
    Sorry I have not answered your handlebar question. But for sure I will not have to lean forward except when I want to.
     
  11. EZ-matic transmission back plate I made. Still a few holes to add. It seems stiff enough but 1/2 x 1/2 6061 stiffener bars can be screwed to the straight sides if needed. Next will the engine cradle for the loop frame. Intake manifold and exhaust manifold stub were ordered this last Tuesday.
     

    Attached Files:

    Last edited: Aug 19, 2016
  12. I have a rear facing intake manifold and flanged exhaust stub ordered and paid for $35.
    AGK was out of stock.
     
  13. bakaneko

    bakaneko Active Member

    Nice, nice. It is taking shape! Cool to see the parts come in and step by step build guide. Found this guy on YouTube; 212cc Predator engine and guy is wearing a Predator (from movies) helmet or mask, LOL. One thing, I always wonder is that this guy and others in the Southwest race these bikes on closed tracks. I wonder if they have any tips or build guides out there. Their stuff sure are impressive.

     
  14. The dude is ugly as hell but he's flying! I know in California where MB's are not street legal for environmental reasons.
    Racing on closed circuit tracks is what they do. You will have to search some of the other MB forums.

    Manifold parts came in the mail Saturday, tubing has to be trimmed and welded to the flanges.
    I have to decide whether to use the stock carb. or purchase a 19mm Mikuni. I have searched many forums and have yet to find definitive specs on the Mikuni.
     
  15. Sportsman Flyer style cradle engine mount to be made this coming weekend. The transmission assy. turned out good.
     
    bakaneko likes this.
  16. bakaneko

    bakaneko Active Member

    Its gonna be a hot one this weekend. Working in the garage on the bike is like sitting in a hot sauna. :(
     
  17. Saturday AM I ordered tires from Wheel & Sprocket in Appleton, Wi and SS flexible exhaust tubing from McMaster Carr.
     
  18. I got in touch with Pat Dolan of Sportsman Flyer this week and had him invoice me for his excellent 79cc Predator Engine Mount System. I also ordered his tank graphics.
    The engine mount will get this build going. With the engine mounted it will allow me to set up the rest of the drive train and hope I get no surprises.
    Also, tires and SS flex tubing arrived.
    I still have to finish gov. removal before I forget how to reassemble the engine.
    AGK has a great video on the 79cc Predator. I learned things not found in the owners manual.
     
  19. Another "What the heck " today. After pulling 6 hrs overtime came home, tapped out the head bearing cups in the Worksman Drop loop frame and intended to install the Monark supplied bearing cups. Nope. Monark bearing cups are 1/32" or .75mm smaller on the OD ( 1.312 VS 1.281" ) than presses into the head. I knew from the start that challenges would arise.
    But this is stupid. It seems my only logical recourse is to machine custom bearing cups that accept Monark bearing and press fit into the Worksman frame head. Producing a tubular shim for the Monark bearing cups even though my machinery could do it. I don't have the steel which would have to be 4140 pre hard to withstand the turning forces 1.312" min. OD 1.281 Max. ID. There are enough challenges in this build.
    I told my wife " This is the year to string Christmas lights on the bike tree.
    Give you one guess how that went over.
    All for now stay busy.
     
    Last edited: Aug 12, 2016
    bakaneko likes this.
  20. bakaneko

    bakaneko Active Member

    There is always something right.
     
    Tom from Rubicon likes this.
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