Author Topic: Yet another M90 Microcosm Hit & Miss thread  (Read 336 times)

Steamandoil (Tim)

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #30 on: May 27, 2019, 08:33:21 pm »
I need to find some pulleys so I can make it work! But under no load, it appears like its going to be a long lived runner. The rubber o-rings were hard to find but Amazon turned them up. Viton buna 70 20mm x 1mm. So far so good on the new rings although they may not be the same composition as stock. The stock rings got sticky and squeaky after a few million strokes. This caused a roaring and vibration that made the engine hit more often to overcome the stiction I believe. Heat probably added to the deterioration of the elasticity of the o-rings.

At any rate it still runs strong now on the original plug and about the fourth set of batteries.




https://youtu.be/-V4Jc4VpbEA
If you play with fire, you're gonna get burned.

IndianaRog

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #31 on: May 28, 2019, 06:21:42 am »
Tim, your little engine runs just as sweet and regular as one could ask...wow!  I have made a note of your O ring source so I can follow your lead should mine develop problems. 

Can you tell me what fuel you are using and what lubricant...then fuel/lube ratio.  I keep experimenting, and currently using 15 parts Zippo to 1 part Marvel Mystery Oil...runs well, but always open to other's learnings as the "manual" is pretty scant on these.

Rog
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Steamandoil (Tim)

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #32 on: May 28, 2019, 09:18:29 am »
Roger I am using about 4cc MMO to 60cc camping fuel white gas. When I pulled the piston everything was nice and oily (including the combustion chamber)
I think the fuel lube can be leaner still. I am also cutting back to oiling the crank and rod/wrist pin about once an hour. (30w) oringsandmore.com has about everything covered, I think 25 were just 3 or 4 bucks.

I'm at the point now where I don't think I can hurt it!
If you play with fire, you're gonna get burned.

Nick

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #33 on: May 28, 2019, 11:37:45 pm »
Very interesting Tim, you've got that one running perfect  8)
Nick

Steamandoil (Tim)

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #34 on: May 29, 2019, 11:53:16 pm »
Thanks Nick!
If you play with fire, you're gonna get burned.

RedRyder

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Re: Yet another M90 Microcosm Hit & Miss thread
« Reply #35 on: June 07, 2019, 06:08:52 pm »
If your new rings start to give resistance, you might get away with just sliding the piston forward enough to put a few drops of synthetic clock oil between the piston rings as they seal almost too well. Nice runner they are. I can't get mine to heat up either. They don't even need water in the hopper unless you make it work hard for an extended period.


They sure are fun!


Gil