Search results

Oh, the humanity! So, I haven't hooked up an ignition to a motor, but I have worked on power electronics. Your ground path is torturous. High-frequency pulses (like what happens when you spark a coil) like to go in straight lines. If you give them a bunch of wires that go every which way...

Each bit is going to have it's own requirements. I'd expect that if you were going to machine the whole thing from scratch that you'd be using a lot of 2024 and 6082 (or 6061) aluminum, along with various alloys of steel. Personally, for an engine that I was going to actually use I'd plan on...

I was totally not thinking of either the fact that a one-lung 2-stroke is going to have a very intermittent velocity (not to mention reverse flow in some circumstances), or that your engine is probably slower than a screaming modern Schnuerle ported production 2-stroke. Carry on, you appear to...

.15 is 2.5cc -- that's an order of magnitude smaller than 20cc. If it were pure suction feed, you could use a carburetor off of a 20cc glow engine (there were a few that big). But looking at that fuel pump, I'm thinking you may just need a carb with a float, and that's a different story. I...

With regards to @petertha's comments: I would be fully in favor of instrumenting the thing and measuring pressure -- except I don't know what it should be! I just do the flip test, accompanied by pulling the thing through compression by hand. If I get a nice springy "pop" when I flip it, and...

Well, the jury won't really be in until you run it for a year straight, then tear it down and inspect for wear. :)

I forgot that - I fly almost exclusively two strokes, in which the fuel pools in the crankcase on a heavy prime, giving you enough for a short burst rather than just a couple of pops.

Uh...

A photograph of the heads may help. Glow plug engines work because the plug wire is platinum, which catalyzes the methanol-oxygen reaction. It doesn't always work without sufficient heat, which is why you need to apply power to the plug (unless you have a really high-compression engine -- one...

I only re-read the story of the broken valve rods today - while 1/8" may be a bit light, it certainly seems that the main problem is the eccentric fit. Did you consider just fixing the problem in the assembly as designed, then arranging for a better rod-eccentric fit before attaching that...

I liked working at FLIR Systems, because when you got a part back from the model shop, you got your drawing, too -- with all sorts of annotations and corrections. In red. It was great. After the second time I gave them a nicely detailed, incorrect drawing, I just started giving them rough...

That's an interesting comment on running in. Car engines manage to run from scratch (well, except for formula 1 engines -- apparently you need to pre-heat them for 30 minutes before you dare start them). But back in the 1990's our ace engine rebuilder would build 'em to last forever -- and...

Particularly after reading the relevant Wikipedia article I'm pretty sure that 90% of the answer is "because it cools the incoming charge and prevents detonation", with a teeny bit of "oh, and it cools it (like an intercooler) so you can stuff more charge in there". It's one of the cited...

If no one's tried it, here's my guess -- I think yes, but they're designed to operate on 5 volts and spin up to 5400 RPM, so you'd either need to rewind them (lots of work with fiddly little bits of wire) or gear them way up. And they're basically 3-phase AC machines, so you'd need to rectify...

Yup. The best 2020 meme I've seen so far is the claim that "2020 hindsight" isn't actually folk wisdom, but a warning from the future that we were all just unable to interpret.

Grind on one? Granted, if I ground on a piece of metal to see what it was, I'd have to spend an hour looking at YouTube to know what the @#$% the sparks meant. But I know it's informative.

I think different engines had different crank timings -- it's part of the charm. I also think that engine has lots and lots of very little very fussy parts. I'm pretty sure I'm not a good enough machinist to even think about building that!

That ended up being a link to the file on Mago's computer -- which will work fine for Mago. It just won't work for the rest of us. You need to use the "Attach files" button, below and at the left side of the screen where you enter text.

I'm drooling over your handy 45 degree angle tool. BTW.

A couple of suggestions from a professional circuit designer: First, check to see if you need heat-sinking on that TO-220 case transistor. The best way to do this is probably to run the circuit at full speed or more, under load (i.e., with a spark plug), for a few minutes. Then shut it down...