Can an 80 cc 2-stroke be mounted on its side?

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NickDK

NickDK

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I have built a ton of motorized bicycles and I am finally moving on to motorizing a small boat. I salvaged an old 10 HP Lower Unit and welded a 44 tooth sprocket to the flywheel, which is horizontal to the ground. Therefore, I am going to have to mount the motor on its side. Obviously, I would need the carburetor to be mounted normally, but that is easy.

Will running an 80 cc 2-stroke on its side (i.e. magneto cover is lying flat, horizontal to the ground) cause damage to the engine or gearcase? Thanks!
 
Allen_Wrench

Allen_Wrench

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Feb 6, 2010
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As long as you find a way to mount the carburettor so that the float is on a horizontal plane parallel with the surface of the Earth (i.e. mount the carb upright somehow, like it's supposed to be) you could even mount the engine upside down. A two-smoker doesn't rely on an oil pump to keep it lubed, so provided you don't run out of fuel, it should be fine.
 
NickDK

NickDK

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Thanks for the reply. That is what I figured. My concern was that maybe the 2-strokes rely on gravity to some degree to pull oil to parts of the crankcase or gearcase. If this is the case, then my fear is that the engine might burn up if these parts are starving for oil. Can anyone confirm or deny this hypothesis?
 
DaveC

DaveC

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Jul 14, 2010
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Old Lawnboy 2 strokes seemed to last a long time with a vertical shaft. Only problem you should have are the normal HT ones ;)
 
rustycase

rustycase

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May 26, 2011
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I can see it now.

Gilligans Island Redux.

Hope it's got enough fins for boat use.
I'd sooner run a vert shaft lawnmower 4 cycle engine. They are all over the place! and cheep!

Good luck,
take yer cell phone with yah!
rc
 
wayne z

wayne z

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Dec 5, 2010
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That may be too much reduction.
Most outboard engines crank up to about 6000 rpm or so, and the lower unit drive shaft and prolly prop too is also turning at that speed.
With that sprocket and engine. the prop prolly wont turn but abt 9oo rpm or less, at full HT rpm.

Actually a 42t on the motor and a 12t on the unit would be closer to right as for rpm at the unit.

I have seen several of these outboard conversions with vertical mower engines, direc drive. They all worked well.
 
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cannonball2

cannonball2

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Oct 28, 2010
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Heres a few pics similar to what you are doing. Its a Briggs Intek 6.5 hp turning a 1950 Scott Atwater 7.5 hp lower unit if found at the dump 20yrs back. Works very well. Its in an old Cal 21 sailboat hull. I rebuilt the lower unit. Fabbed the rudder and steering. The Briggs drives it directly via a lovejoy. Under the engine box is a 20 amp belt driven Denso alternator to keep the boats batteries charged. Cruises at hull speed @ 2100rpm, burns about a quart an hour.
 

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happycheapskate

happycheapskate

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Nov 26, 2009
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Sounds neat. I'd like to see how it turns out. How are you going to start it? Are you going to get a happytime type pull-start? The instructions that came with my Grubee said the motor could be used to re-power lawn equipment or stationary power equipment, so I don't see why it wouldn't work. Maybe put the gear case on top so the clutch doesn't end up greased. PS, maybe seal the magneto case with something, I've heard of riders getting a little water in them from the front tire and making for a long ride home.
 
Saddletramp1200

Saddletramp1200

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May 7, 2008
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My only worry is getting oil to the top side crank shaft bearing. Also over time a build up of oil in the case. But after talking to my Uncle he said if the gaskets are sound, should not be a problem. You may want to look into a diaphram type carb for it tho. Marine 2 stroke motors work off pressure from the fuel tank. Here we go again, boldly into the unknown. I love it. :) Good luck and keep us posted. (c)
 
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happycheapskate

happycheapskate

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You can get small vaccuum operated fuel pumps for 1/4" fuel hoses, for $15-30 from almost any go-kart racing or lawnmower shop.

http://www.heeters.com/images/snb42-5315.jpg

Saddletramp1200 said:
My only worry is getting oil to the top side crank shaft bearing. Also over time a build up of oil in the case. But after talking to my Uncle he said if the gaskets are sound, should not be a problem. You may want to look into a diaphram type carb for it tho. Marine 2 stroke motors work off pressure from the fuel tank. Here we go again, boldly into the unknown. I love it. :) Good luck and keep us posted. (c)
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