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HomeAircraftHelicopterMain Discussion › Nitro Engine corrosion from gummed fuel
08-06-2017 05:44 PM  12 months agoPost 41
utahbob

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St. George Utah

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if there's scoring
It could be alot to remove maybe .001 or more..if honing to just get the glaze out and restore crosshatching it could be a few tenths..I've tried doing this stuff before..what happens is you get tired of taking the stuff apart and puting it back together a bunch of times..then you realize you'd rather be flying more than wrenchin!..

I do a great decending funnel!

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08-06-2017 06:22 PM  12 months agoPost 42
EEngineer

rrProfessor

TX

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Honing doesn't work with an ABC or ABN engine...as the sleeve's diameter varies slightly from bottom to top....as does the piston diameter.

With a ringed engine, as material is removed from the cylinder sleeve from honing, the piston ring must expand more and more...depending upon the ever expanding sleeve diameter from the honing process....to seat against the sleeve for compression.

And the piston ring can only expand so much...

When replacing the piston ring, the ring is expanded to slip over the piston to be seated in the "groove"....during this process, the ring is not circular, it is slightly elliptical...and then "springs" back to it's circular shape.

One certainly cannot use an old ring on a honed out cylinder in an attempt to bring back proper engine performance....a new ring with a new sleeve is required....

Also, at top dead center, the sleeve's diameter may be ever so slightly smaller than at bottom dead center for proper combustion purposes....and honing can mess this up.

Logo 600SXs, 800XX, TDR IIs

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08-06-2017 10:26 PM  12 months agoPost 43
InvertedDude

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USA

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The numbers game
I did a quick compression test with a new engine and the junk engine. Using the starter shaft (R50) moving it over with my fingers. This doesn't past scientific test, unless anyone got a way to measure it.

New engine was kind difficult to turn over with my fingers but I could do it.

The junk engine was easier to turn over, I would say maybe 20% easier.

There is no question I lost some compression, but what amount of % compression unless tested?

This is what I can confirm to you all. It flies and flies well while remaining at a controlled temperature in my helicopter. FF and hovering is great, I had to back off my throttle curves in idle 1 up. Is it the most powerful engine? NO...but it flies while you wait for parts in the mail.

That was my whole purpose here, not getting into the numbers game.

It will push a trainer 40 plane straight up into the air, there is no doubt about that in my mind. I can't wait to get some videos so we can all laugh at it!

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08-06-2017 10:56 PM  12 months agoPost 44
JuanRodriguez

rrProfessor

The Villages, Florida

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Main purpose of the whole exercise is to have fun and enjoy the hobby....

Sounds like you're doing just that !

Carry on......

Been there, done that and old enough to know better.....

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08-06-2017 10:57 PM  12 months agoPost 45
InvertedDude

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USA

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JuanRodriguez
Exactly my friend! I appreciate you!

If I was anywhere close to you, I would fly with you!

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HomeAircraftHelicopterMain Discussion › Nitro Engine corrosion from gummed fuel
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