Geared Outboard

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David Dias

Active Member
Joined
Oct 14, 2009
Messages
44
Hi,

This is a geared outboard using a OS lower end and a gearbox. Turns very easily a prather 235. The engine is a STS on road with a silver bullet pipe. The first test was with a dumas hot shot sprint 7.5 and

it´s very promising. Now I will try with a JD WOF 34 and with a Shaman





















The video engine .21 runing on Dumas 7,5cc:

 
very nice David, so what's the gear ratio?,,what speed your getting? keep posting..

jul
 
When I built my .12 geared outboard,I figured out the ratio based on the rpm of the .12 engine versus the rpm of the .21 engine. My goal was to use my best .21 props on the .12 engine. My Sirio .12 engine will turn about 40,000 rpm and my CMB.21 will turn about 30,000 rpm. I wanted the prop to turn the same on my .12 as it did on my .21. It is much easier to find props to use this way. I am currently working on a .21 Orion CRF geared outboard to try on my HTB290. The Orion CRF series of engines are the hightest turning engines I have found. The CRF has the crank intake hole drilled at an angle so the crankshaft acts like a "supercharger".

Bob Kensill
 
When I built my .12 geared outboard,I figured out the ratio based on the rpm of the .12 engine versus the rpm of the .21 engine. My goal was to use my best .21 props on the .12 engine. My Sirio .12 engine will turn about 40,000 rpm and my CMB.21 will turn about 30,000 rpm. I wanted the prop to turn the same on my .12 as it did on my .21. It is much easier to find props to use this way. I am currently working on a .21 Orion CRF geared outboard to try on my HTB290. The Orion CRF series of engines are the hightest turning engines I have found. The CRF has the crank intake hole drilled at an angle so the crankshaft acts like a "supercharger".

Bob Kensill

Hi,

Nice can you add some photos?

Thanks

Best Regards

David Dias
 
When I built my .12 geared outboard,I figured out the ratio based on the rpm of the .12 engine versus the rpm of the .21 engine. My goal was to use my best .21 props on the .12 engine. My Sirio .12 engine will turn about 40,000 rpm and my CMB.21 will turn about 30,000 rpm. I wanted the prop to turn the same on my .12 as it did on my .21. It is much easier to find props to use this way. I am currently working on a .21 Orion CRF geared outboard to try on my HTB290. The Orion CRF series of engines are the hightest turning engines I have found. The CRF has the crank intake hole drilled at an angle so the crankshaft acts like a "supercharger".

Bob Kensill

A Orion CRF???????????????

Never heard of it.

I guess I need to google on that one.

this?? :

http://www.google.nl/images?hl=de&q=orion+crf&um=1&ie=UTF-8&source=univ&ei=_N7cTMzILYWVswamgNGSDA&sa=X&oi=image_result_group&ct=title&resnum=2&ved=0CCsQsAQwAQ&biw=1217&bih=786

But interesting Bob.

Ronald
 
Last edited by a moderator:
Going to run my .12 outboard today. Will take some pics of both boats. The .21 boat is not ready yet but will test soon.
 
Here are a few pics of my geared outboats. The grey boat is a Graupner Formula One. It is running the Sirio .12 engine that I used to set the A outboard tunnel SAW and Oval records. The Oval record still stands. The white boat is the Leecraft XT120 during the Oval record attempt. There are three more pics. One is the powerhead of the .12 Sirio. Next is the Orion .21 CRF powerhead. Last is the .12 Orion CRF next to the .12 Sirio. Notice the grooved flywheel on the .12 CRF. That is the supercharger drive pulley,but that is another story.
 
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