25HP Yamaha powerhead-E bay

[STEVE FRENCH]

http://cgi.ebay.com/ebaymotors/ws/eB...1123&viewitem=

Anyone know if this is a "loop charged" or "deflector" piston motor?.....(Looks like a "minnie-me" 45 OMC!)

Twin carb ??

19P

[sax]

http://cgi.ebay.com/ebaymotors/ws/eB...1123&viewitem=

Anyone know if this is a "loop charged" or "deflector" piston motor?.....(Looks like a "minnie-me" 45 OMC!)

Twin carb ??

19P

By the way the port runners are cast in the block, I would have to say it was a looper.

[mdaspit]

http://cgi.ebay.com/ebaymotors/ws/eB...1123&viewitem=

Anyone know if this is a "loop charged" or "deflector" piston motor?.....(Looks like a "minnie-me" 45 OMC!)

Twin carb ??

19P

How about you guys give me a quick lesson in what's the difference?

[Art K]

Yamaha 25

This is a legal motor In NBRA C- mod class. It is loop charged and has dual carbs. I have not seen one run yet. Dick Falbe coincidently called me today and told me that Jack Kugler just completed a 25 Yamaha for him that they had been working on for the last couple of years. Said it has been on the dyno and shows real promise. NBRA allows Yamoto 102-202- 302, Merc 25 & Yamaha 25 With any 14-15 gear ratio lower unit. Any expansion chamber. Any ignition system on the Merc & Yamaha. I have built a Merc but only run it the last couple of years a couple of times. Too many other classes. But the 2 times we have run it ran very good. Got a full time driver for it this year. Hope fully we will get it worked out now.
Art K

[STEVE FRENCH]

How about you guys give me a quick lesson in what's the difference?

Loop charged has flat top pistons and runs well with expansion chamber(s)......This also means they are quieter than a deflector piston motor with open stack/megaphone......Most deflector motors have a bridge or dam on top of piston that works with port timing.

From what I've seen/learned, a loop charged motor has more power potential and quieter since they will produce power over a wider rpm range with a chamber.

Anyone care to go into detail?

19P

[sax]

How about you guys give me a quick lesson in what's the difference?

Here is a very simple and to the point explanation of schneurle porting
better known as loop scavenging:

http://www.doddington-kent.org.uk/pl.../schnuerle.htm

[mdaspit]

I'm easily confused

Here is a very simple and to the point explanation of schneurle porting
better known as loop scavenging:

http://www.doddington-kent.org.uk/pl.../schnuerle.htm

Non schnuerle ported engines or 'loop scavenged' engines have only one port opposite the exhaust port

If I read this correctly, schnuerle engines are not "loop scavenged"...Right?
Does that make them "deflector type" or can you have a non schnuerle
engine without deflector type pistons?

[David_L6]

The explanation at that site is a bit confusing. Most people would call Schneurle porting and loop charged the same thing. Try this link and see if it clears up anything.
http://en.wikipedia.org/wiki/2_strok...flow-scavenged

[mdaspit]

Thanks

The explanation at that site is a bit confusing. Most people would call Schneurle porting and loop charged the same thing. Try this link and see if it clears up anything.
http://en.wikipedia.org/wiki/2_strok...flow-scavenged

Oh yeah, that's a great site, cleared it right up for me, complete with animation.

Thanks a lot-