Another version of how not to build a model engine

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sorveltaja:
About that bearing disk, that I mentioned earlier; it really isn't 'bearing' disk, as it's a static part.
Since I don't have suitable size steel stock, I'll make that disk by stacking an M8 washers, and silver solder them together:

before... ...and after.

The disk in place:

It needs to be shortened, so that it can be attached to crankcase backplate.

If my memory serves, this kind of system has been used on glow engines.

NickG:
sorveltaja,

I think the nut would have been a fine way of stopping it coming off. It shouldn't have come undone, the only reason I can think it did was if the conrod was slightly thicker than the length of the crank pin, it should have been the other way around.

Still, your new method should work as long as there is no binding between rod and that disc.

Nick

sorveltaja:
Nick, the recent nut-system should have worked, as my purpose was to make a slow runner. But the engine runs at too fast speed, causing more vibrations, than I ever expected.

But it's just one of those bugs, that needs to be stomped.

Here is the bearing plate attached to backplate. Fastening is done by two M2 screws:

And here are the plate + crankcase backplate in place:

So it's about time to re-assemble rest of the engine :ddb:.

sorveltaja:
Before assembly, slots for primary gear and flywheel's grub screws needs to be done:

Testing that they fit ok:

bogstandard:
In all honesty S, your over revving just might be because you have a too large carburettor throat. I would try about half the diameter you have now and see if it makes a difference, you can always open up in stages of 0.1mm until you reach a good compromise. On small engines like yours, 3mm or 4mm would be classed as a racing bore, designed for getting the engine into a higher rev range by over fuelling it.

The reason I suggested sewing needles is because they have a very shallow taper, so allowing you to use a coarser thread for adjustment, plus they will be much smoother than a needle you make yourself.

Bogs

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