Author Topic: How much compression is too much?  (Read 1275 times)

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Offline Al Smith

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Re: How much compression is too much?
« Reply #50 on: December 31, 2011, 09:21:10 am »
I would be curious if somehow an engine could be spun up like an air compesser exactly how much it would raise over static .Of course with no source of ignition it would leave out the factor of a rapid expansion of the combustion to tighten the rings  .

I know for example that a 2100 Huskey thick ring version like I have is one of the toughest SOB's to roll over ever made .The highly sought after thin ring piston pulls a lot easier and evidently then relies on ring expansion because that's the one they want if they are making a cookie cutter .

I can't imagine trying to drop start the version I have unless you weight about 300 pounds and have gorrilla arms .

Like Kevins big Sachs or those couple of 084s' you just shove down on the handle and pull the rope ,they fired right up .That damned Husky you have to have a foot in the handle and a good grip on the d-handle  else it will  try and suck you backwards through the recoil .

Offline EHP

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Re: How much compression is too much?
« Reply #51 on: December 31, 2011, 02:36:22 pm »
I have both thick ring 2100 and thin ring , the only reason everyone wants the thin ring is the ring and piston does not break as easy as the thick ring but still the thin ring piston will break the ring land , on my computer program it has just about everything to do with this kind of stuff , it will even tell you if you punch in your porting numbers if your numbers make sense , if your ext or transfer ports are to high it will tell you so

Offline Cut4fun .

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Re: How much compression is too much?
« Reply #52 on: December 26, 2013, 03:12:02 pm »
Wonder what ole Aric aka Troutfisher is up to now days.  Good with the file and other chainsaw stuff.
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Offline KilliansRedLeo

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Re: How much compression is too much?
« Reply #53 on: December 26, 2013, 06:56:19 pm »
In the late 60s/70s one of the things we sometimes used a dykes ring on the race bikes, just wondering if that type of ring has ever been used on a saw? If so did it make any difference?
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Offline 660magnum

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Re: How much compression is too much?
« Reply #54 on: December 26, 2013, 11:46:58 pm »
The ERA of the Dykes has passed. Too much friction (during cylinder firing?) and doesn't last very long?

I remember 50 years ago that it was going to be the ring of the future.
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Offline KilliansRedLeo

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Re: How much compression is too much?
« Reply #55 on: December 27, 2013, 10:00:11 am »
660 you are correct about the wear! On the bikes less than 250cc we were replacing the rings every other race. 250 and greater we were doing a ring job every race. However at that time the big Husqvarnas were using an aluminum jug with a spun cast iron liner rather than the chrome plated bore on the Japanese types. So wear on the cylinder liner was not so much of a problem.

You knew when the ring needed to be replaced because usually the bike could barely pull itself unless WFO!
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Offline 1manband

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Re: How much compression is too much?
« Reply #56 on: December 27, 2013, 02:20:57 pm »
lots of good information.

think it was ehp(?) mentioned trapped compression ratio.  donno if its a common practice to cc the chamber.  could be worthwhile if someone knows what would be a good number to shoot for.  i sure dont.

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