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West Wight Potter Mailing List maintainer
dfarrell@ridgecrest.ca.us
List hosted by www.tscnet.com
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eric,
i've got the manual for my tohatsu 2.5.....at home. when i get home from
this trip (apr 2) i'll check it out and report back.
Ken Silverman, poop-15, "vegan lorax", bothell, wa
On Tue, 21 Mar 2000, Eric Johnson wrote:
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> West Wight Potter Mailing List maintainer
> dfarrell@ridgecrest.ca.us
> List hosted by www.tscnet.com
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> >The crankshaft is used to take the motion of the piston and rod and convert
>
> >it to a cercular motion to drive the prop.
>
> Thanks for clarifying that, but I don't think anyone was disputing that :-P
>
>
> >the crankcase on the otherhand is
> >under presure when the piston comes down and vacume as the piston goes up.
>
>
> on a 2-stroke, yeah, as SF pointed out. I was thinking 4-stroke earlier, and
> every 4-stroke engine I've ever owned has been generally under crankcase pressure.
> Now that I think about it though, i suppose a 1-cylinder 4-stroke might create
> a little crankcase vaccuum on the compression and exhaust strokes, since theres
> no other cylinder on a power or intake stroke to cancel the volume displaced
> by the moving piston.
>
> I had forgotten about the pumping action of the crankcase in a 2-stroke. The
> vacuum there certainly could drive a fuel pump. But I just never noticed having
> a fuel pump on my tohatsu, and the owner's manual does not speak to a fuel pump,
> nor can I find replacement pump parts in any of the online sources. If there
> is one, i'm sure its in there somewhere (maybe integral to the carb?). I had
> just always assumed that the venturi in the carb would be enough to suck the
> small amounts of fuel used by a small outboard up the short fuel hose. Does
> anyone here have an actual service manual for one of these small outboards (specifically
> the Tohatsu/Nissan) that tells for sure?
>
> The upshot of all this is, of course, that if these small outboards don't require
> a fuel pump, whoever wanted to try using an external tank may be able to do
> so with some simple fittings.
> http://www.nwlink.com
>
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