Kimjon

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Everything posted by Kimjon

  1. Welded both sides for extra over the top strength. I'm not too keen on coming off like @Muncie at top speed and braking my neck. And done! It's all getting a paint job later, so that will tidy up the ugly.
  2. Now jumping on to brakes. I've added a disc brake to this goped. It was missing its brakes, so I hacked off whatever brackets were there and started again: A few holes and a couple minutes with a grinder made this sexy bracket. Gotta love a good bracket! Tacked in place.
  3. Finished the manifold. I'm pretty sure its going to work. Here it is loosely in place
  4. Original manifold milled down flat, this will bolt to the motor. Port matching to the other manifold shape. A pulse port drilled in the side to run the fuel pump/diaphragm. Test fit...Fucking ugly as sin, but should be functional. I'll grind off any excess material later to try make it look a wee bit better than it currently does.
  5. I ordered a diaphragm style carburetor kit from eBay, it arrived in record time...But it would have been awesome if they'd sent me the right one. The manifold in the kit was for a completely different motor! It only has two mounting holes, but my motor has four. Countless emails, achieved nothing in the end...I just wanted the shitty Chinese manifold for fuck sakes...But in the end they offered a part refund instead, which leaves me no further ahead. So, solution:
  6. Exhaust then got VHT ceramic paint And that's about it for now.
  7. I further milled a step on top to add clearance, and used the dremel to smooth it out And then installed it, perfect! Follows the crank, allows a nice wide opening, flow is now going the right direction...think it's getting there now.
  8. Now they fit: But I don't like the angle, its to restrictive and the reeds hardly open. So hell bent on thinking I can do better than the factory i further milled the base to change the angle.
  9. On to the reed valves. In my opinion, they face the wrong way in these motors? The air/fuel is dragged in, up and around the massive reed support. I've flipped them around so that the air/fuel mix is pulled cleanly through them unobstructed. Fingers crossed this is the right idea??? However, problem is they don't fit! So I'll make them fit!!! Okay...truth be told it was never going to hold how I clamped it above and it moved on me, so take 2 below: Mmmmm pretty...
  10. Okay...more porting, followed by more porting... I'll do a bit more on the flow side and then polish it up again.
  11. Piston received a little love. It was black as black can be with carbon build up. Here it is after 10 minutes sanding: Still looked shit...so I broke out the random orbital, couple minutes on that, then on the buffer wheel...finally got the dome polished where it needs to be. That was way more work than anticipated.
  12. Here's a before and after photo to see the difference And after And hopefully that equally more flow, and will be one of many things that add up to more power. Next up for the motor is to calculate its port areas, timing, squish band and compression...then tweak those with yet more porting.
  13. Roughing it out Still a bit of work to do, but already a huge improvement. When I'm happy with the "flow" it will get polished up. The intake should be rough, the rest should be smooth
  14. Here's a view of the piston placed exactly where it ends up at BDC. note the skirt is to long and the sides of the barrel don't match. And here it is after matching Now it's a matter of matching to (barrel) to the cases.
  15. Here it is with the crank and piston installed. The open style of cylinder with a removable head allows me to port time the motor. I'll stick a degree wheel on the crank, turn it over and measure the degrees at which the ports open and close. Once I have this data, I'll know where improvements can be made.
  16. I'm going to flow the bottom end by porting/blueprinting it. Things like this lip the cylinder makes as it protrudes into the lower case will be reshaped to "seamlessly flow". The arrows I've drawn on indicate crank rotation. That sharp shelf in the photo above will receive a lot of work in this area. Any area like this will create poor flow due to an eddy forming in the low pressure area. The basic idea is that a motor is simply an air pump, and the more efficient that pump is...the more power you'll make.
  17. Jumping back to the motor. This motor was a $20 buy off trademe. It came on a totally fucked pocket bike, that was stored outside with no spark plug in the motor for God knows how long? In that time the motor filled up with rain water. I turned it over by hand and it pumped the water out. Luckily the oil in the 2-stroke mix saved the internals. But the bearings are toast! I used an old clutch to make a gear puller to remove the clutch on this motor. It was well stuck...but this tool popped it right off! With that out of the way, I stripped the motor right down. Externally its really suffered from its poor storage, but internally it all good. I'll probably sandblast it after porting, so it will look like new and its dirty past will be something we both pretend never happened
  18. Im jumping back and forwards a bit, but that's the reality of these projects. I tend to do as much as I can until I hit a barrier that stops me going any further...Then jump ahead and work on something else, to prevent losing momentum. So in saying that, back to the sprocket: I traced the brake caliper, as this will share the same PCD as the sprocket. Much easier to work with on paper, and soon I had the spacing sorted. I drew circular guidelines to locate the sprocket.Then used the centre to take all measurements from. I blacked out the area and scribed a diameter 65mm circle. This sprocket had 68 teeth, so been a nice even number the quarters equaled to 17 teeth. 68/4=17 And that split the diameter 65mm circle into 4. Giving a mark to centre punch and drill. Sorted!
  19. Shouldn't be hard to do. But may be easier with like for like?
  20. Then I made sure what's left of the gasket contact surface was given the best chance of sealing by sanding it flat. Next I stuck the cylinder in the lathe and made sure the sealing surface was true by turning a minute skim off the face. Then test fit the head. All's going to plan so far. I'll attack the bottom end tomorrow where I'll make some big changes.
  21. I made a paper gasket then marked out the port shape. Very much a case of trying to fit a square peg in a round hole! But the pulse back from the expansion chamber will love this smooth(er) transition, and make more power. Then realised that I could just use a circle template to do the same thing I ported, then kept checking with this template that all was good. Happy enough with this for now.
  22. Okay, got a bit of spare time last night to break out the die grinder and start porting the motor. This is the before, look how rough those ports are...the chamfer looks like it was chewed by rodents!!! It would still work and that's how they all look inside. Fundamentally these are good motors, the only thing letting them down is the QC (lack of) before sending it out the door. With a bit of work you can make them pretty tidy and add a bit more horse power in the process.