Gas/ oil mixture??

[robert graham]

Boscoe, did you mean the crankshaft reversed or the prop shaft?....

[boscoe99]

Both. There was no dog clutch. If the engine turned one way then the propeller shaft turned one way. When the engine turned the other way then so to did the propeller shaft turn the other way.

[BQUICK]

Yeah, they momentarily shut off then restarted running backwards. But if it stalled in the process....hence the nickname "dockbusters".

[robert graham]

Yeah, they momentarily shut off then restarted running backwards. But if it stalled in the process....hence the nickname "dockbusters".

Well, live and learn....I never knew about this.....

[99yam40]

On some old motors to get reverse you just spun the motor 180

I am supprized they have not put multiple gear transmissions in these things yet

[boscoe99]

On some old motors to get reverse you just spun the motor 180

I am supprized they have not put multiple gear transmissions in these things yet

Variable pitch propeller.

[greasyshaft]

I suppose a CVT would do the job.

[rodbolt17]

Have a 15sf 1989 Yamaha no owners manual.what mixture do i need . gas/oil.
there is a decal next to the gas plug in that reads 100/1 is this correct?

for the young pups
the dock buster used a direct drive transmission.

it also used a twin solenoid starter motor.

in the N(off position) motor dead.
however moving the shift lever to the FWD or REV position activated one of two solinoids.
that was the difference between fwd and rev.
just depended on which way the motor was started.

two strokes back in the day, unlike 4 strokes, simply did not care wich way the crank was turning at engine start.
they would,and still will, run either way.

[99yam40]

I remember driving an iron lug case tractor up a steep ditch with not enough throttle to it and it died and fire back up running backwards.
the oil bath air filter turned into the exhaust pipe and oil went everywhere.
Some motors do bot care which way they turn when running.
at least in the old days that was true

[ausnoelm]

Yes, correct, old time 2 strokes could run either way, I remember plenty turning over, then giving a bit of a "kick back" and suddenly forward gear was going in reverse, if you knew what was going on, you simply turned the engine off, and restarted it again, but this time, turning the right way.

[rodbolt17]

if you don't believe a 2 stroke can run backwards find an old OMC 55-60 3 cyl with the twin points and the amplifier ign.
remove the anti reverse spring.
watch it spit and run backwards.

[TownsendsFJR1300]

Yes, correct, old time 2 strokes could run either way, I remember plenty turning over, then giving a bit of a "kick back" and suddenly forward gear was going in reverse, if you knew what was going on, you simply turned the engine off, and restarted it again, but this time, turning the right way.

Back in the late 70's my friends yamaha YZ250cc two stroke (motocross bike-actually a 1975 model), would change crankshaft directions WHILE RUNNING (rev and decel).

Stick the engine in gear, slowly release the clutch, 5 REVERSE speeds!!!

ECM's were pretty new at the time, I don't remember what he did to fix it..