Since acquiring a Tohatsu M9.8A and trying to find information about it, which is mostly non-existent, Paul and Sea Rider helped convince me that it is indeed an obsolete one-of -a-kind.
I got an A model parts book and Sea Rider posted a Model B parts book for comparison.
Thank you both and others who responded.
They were right, (as I expected), this A model is obsolete and truly one of it's own kind!
After working through comparing all the parts diagrams, I don't think there is a single part that would interchange except screws or bolts!
So in case anyone is interested, here is my take on the original, and the differences.
The A model was basically a 'prototype' without most of the common features of an outboard motor, especially the powerhead.
A uses a dirt bike style carb with a central slide and no attached fuel pump.
B is a more typical OB design carb and pump.
A has a mag with points. B has SSI
A has no spark advance on the mag mounting plate connected to the throttle or carb
B has the typical moving advance plate integral to throttle and carb.
A has 2 individual coils, B has a double coil unit.
A appears to have only bushings on the top end of the rods.
B has needle bearings throughout.
A throttle is one cable to the carb slide only.
B throttle is 2 cables and linked to the mag plate.
The castings and hence the gaskets are all different shape, none the same.
Both have reed valves but slightly different shape and housings.
Recoil starters look similar but are different.
Everything below the powerheads is different, including the impellers.
Obviously Model B came up to more common OB design.
So much for finding A model parts from B model or newer ;-(
It has been an interesting venture for an OB newbie, just thought I would pass on what I found in case it might help someone else.
Again, thanks to all here who continue to help me figure this boat stuff out.
I got an A model parts book and Sea Rider posted a Model B parts book for comparison.
Thank you both and others who responded.
They were right, (as I expected), this A model is obsolete and truly one of it's own kind!
After working through comparing all the parts diagrams, I don't think there is a single part that would interchange except screws or bolts!
So in case anyone is interested, here is my take on the original, and the differences.
The A model was basically a 'prototype' without most of the common features of an outboard motor, especially the powerhead.
A uses a dirt bike style carb with a central slide and no attached fuel pump.
B is a more typical OB design carb and pump.
A has a mag with points. B has SSI
A has no spark advance on the mag mounting plate connected to the throttle or carb
B has the typical moving advance plate integral to throttle and carb.
A has 2 individual coils, B has a double coil unit.
A appears to have only bushings on the top end of the rods.
B has needle bearings throughout.
A throttle is one cable to the carb slide only.
B throttle is 2 cables and linked to the mag plate.
The castings and hence the gaskets are all different shape, none the same.
Both have reed valves but slightly different shape and housings.
Recoil starters look similar but are different.
Everything below the powerheads is different, including the impellers.
Obviously Model B came up to more common OB design.
So much for finding A model parts from B model or newer ;-(
It has been an interesting venture for an OB newbie, just thought I would pass on what I found in case it might help someone else.
Again, thanks to all here who continue to help me figure this boat stuff out.
