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Everything posted by Kimjon

  1. These chambers vibrate like hell, and eventually this will fatigue the metal. I added a support bracket, and a little tab to the muffler as well. Here's how I made the support bracket. All welded, and the muffler tab added too. This metal is super thin and a challenge to mig weld. You'll be going good like a welding God, then it blows a huge hole...but that's the game we play.
  2. Waiting around isn't one of my strong points, so to move this project forwards, I welded it straight this morning. I think it looks the part
  3. A couple more pics. the cardboard is a mockup of a rear fender I'll make/add. And the yogurt container is there to help me visualise a gas tank. Next up: I'm going to port the motor and add a larger carburetor with a diaphragm pump, so I don't have to mount the tank higher than the motor, then tidy it all up.
  4. I cut a port in the main pipe with a step drill to match, and welded it in place. Once again using a string line to centre it. Then I closed of the tip of the cone where the old muffler was, as the exhaust will no longer exit there. I'm going to curve it around and point it down towards the ground...but I couldn't help taping it on just to get a feel for how its going to look. I'll give it more time, as this look is growing on me. I may just weld it up like this?
  5. Then I fitted the muffler. I cut this off another pocket bike, welded an extension that was approximately 60% the size of the header pipe diameter to restrict exhaust flow.
  6. Going for a centrebleed pipe, so marked out location of bleed port. String line gives a centerline, just mark each side of the string. then find the tangent and mark that.
  7. So, some rules of thumb. The longer the header, cone/s and barrel length are the broader the power band will be over the useable rpm range, but less intense. Inversely: a shorter header, cone/s and barrel length gives a much sharper and more aggressive power band, but this only happens at a higher rpm. For this project running a centrifugal clutch, I'm keen to have a broad softer starting power band with a wide midrange. Well that's the theory...reality check to come.
  8. I feel like I'm winning on this one now, as the expansion chamber starts to take shape around the rear end. Cut, shape and tack: And then welded: I need to pick up a large bend to tie it to the other cone, but I have a plan (mates scrap bin)
  9. Struggling to get the shape I want, but nothing a hacksaw, welder and some more thinking time can't solve.
  10. On to the exhaust expansion chamber (yes that rather rusty one in the above photos). There's an entire science dedicated to these...and I've used none of it "designing" mine. What I have is a reasonable past history with 2-strokes, so I'm simply going by what feels right. At the end of this project I'll soon know if I did the right thing or not?
  11. Playing around with the proportions. I want to pay homage to the original, by keeping the look it had. I've seen some homemade variants of these using gravity fed fuel tanks stuck on top in the past that just kinda miss the mark style wise. It's a fine line getting something proportionately correct...fingers crossed it will look the part when finished?
  12. Welded up the engine mount: Then fitted this to the frame And finally popped the motor on for and overall first impression. So far, so good.
  13. So onto the build: Engine will be a pocket bike 49cc motor. I have a few of these now, parts are cheap and easy to get and they're pretty good motors for the money. I started by cutting up the pivot mount, just visible behind the wheel. Then I cut the engine mount out of the donor pocket bike also purchased from trademe for $30. I brought the pocket bike for the motor, but the extra bits like this also come in handy and can save a lot of work.
  14. Anyone with a keen eye will notice a few parts are missing, but for $23.50 what do you expect? However I see this as an opportunity to improve a few things that the original design didn't quite get right. 1) The original was only 22.5cc, it still did 20mph...but there's room for improvement. 2) The original had a tension cable that moved the motor directly onto the rear wheel, where a knurled friction drive would make contact with the rear tyre to drive it. This system wears out tyres, and slips in the wet. I'm going to look at a chain drive alternative. Those are the main impro
  15. Fast forward about 40 years and unfortunately I still can't justify/afford to rock up to a shop and buy a brand new one, however this fabulous opportunity presented itself on trademe. Now I know what you're thinking, but sadly I had to pay extra for the coffee cup...it wasn't included in the $23.50 I paid for it.
  16. Hard act to follow @Muncie with a fucking V-twin on a goped!!!, but if imitation is the sincerest form of flattery...then this is my lame arse attempt. So, ever since I was a kid I've wanted one of these It was called the "Bigfoot" and to a little boy growing up on a bush block with no concrete within about 5km, it appealed to me as something I could rip around the gravel driveway on. However the excessive price tag ment it stayed a dream, as I never got one (rightfully so, these things were something like $1500 to buy in NZ during the 1980's).
  17. Then did wallpaper, a desk and shelves: She'll pretty it up with girly shit later when completely finished
  18. Then I made the furniture for inside the office. Filing cabinets, used to make a storage unit/seat: Got to get some foam and material to do the upholstery for the seat.
  19. I put this side, but never found a use for it... if it's of use to you, you're welcome to have it?
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