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  • October 20, 2020, 08:52:07 AM

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Author Topic: 4 Stroke reduced weight  (Read 682 times)

Offline Dennis Toth

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4 Stroke reduced weight
« on: April 14, 2019, 05:09:38 PM »
Does anyone offer machining of the crankshaft to bore out the center and reduce weight of 4 strokes?

Best,   DennisT

Offline Bob Reeves

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Re: 4 Stroke reduced weight
« Reply #1 on: April 19, 2019, 05:16:05 AM »
No reason to even think about it especially if it's a later model Saito, engine weight isn't an issue at all with the 40,56 and 62, with maybe a little consideration on shortening the nose a bit for a 72.

Offline Dennis Toth

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Re: 4 Stroke reduced weight
« Reply #2 on: February 06, 2020, 06:01:05 AM »
I disagree, people do extraordinary things in stunt to save 1/4 oz or less. If the crank on any of these 4 strokes could be lightened you could save between 3/4 and 1 oz., same strong steady power, less weight, that's a good combination. In stunt it is a big deal, just say'en. 

Best,     DennisT

Online Massimo Rimoldi

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Re: 4 Stroke reduced weight
« Reply #3 on: February 06, 2020, 06:52:56 AM »
Hi Dennis,

Be careful to lighten the engine's parts  , especially in a 4Stroke
A friend of mine (about twenty years ago) replaced the ball bearings of a 4Stroke with a smaller size to save weight.
He soon discovered that the ball bearings's life had decreased with their weight due to poor lubrication, but he didn't like how he found out.

Massimo

Offline Dennis Toth

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Re: 4 Stroke reduced weight
« Reply #4 on: February 06, 2020, 12:35:03 PM »
Massimo,
I understand about not going to far. Changing bearings to non OEM type particularly going smaller is going to stress things. With the crankshaft at least on the ones I've see it is solid steel. Since we don't need base compression in the 4 stroke boring out the shaft while leaving a reasonable wall thickness should be doable without changing the engine run. It seems like a simple way to reduce weight by up to an oz. but you need to have the proper machinery to do the job without cracking or distorting the shaft. Just seems a way to take a pretty good power plant and take it to the next level as it already uses about half the fuel weight.

Best,    DennisT 

Offline Dan McEntee

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Re: 4 Stroke reduced weight
« Reply #5 on: February 06, 2020, 06:57:20 PM »
   Tear your four stroke engine down and weigh the crank shaft. I think you may be surprised at how light it is already. The only thing that is heavy on most four strokes is the muffler, and much weight can be saved there by running simple tube mufflers like Saito makes for their engines. Just enough back pressure for a pressure line to the fuel tank. I would be VERY hesitant to go fooling around with such a quality manufactured part like a crank shaft on such a high dollar engine.
  But if you would like to take the point on this one and have the work done, I'll sure be glad to read about the results, one way or the other.
  Type at you later,
  Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Robert Zambelli

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Re: 4 Stroke reduced weight
« Reply #6 on: February 27, 2020, 01:21:23 PM »
I totally agree with Bob.
I've had around twenty planes powered with 4S engines and I've never had any desire to modify them.
I consider the SAITO to be the best for C/L flying.
There is absolutely no reason to modify a 4S engine other than custom venturis.
I have SAITO, ENYA and OS 4S engines. I really like them EXCEPT for the OS Surpass 40. I have had three of them and they are, in my opinion the WORST engines I've ever owned.

You might be surprised at the weight comparison.
Take a look at the ENYA 53 and the ST 60 weights.
And, the ENYA will run rings around the ST.

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