Yamoto 302

[Lester Connor]

Hi people. I'm considering putting a 302 on a historic Kelly Jupiter as a working exhibit in a museum. The boat has not be on the water for 25years, a piston having emerged from the side of its circa early '60s Konig. Whilst I'm repairing the original engine is there any simple mods I can perform on a 302 to replicate the performance of the boat - about 75 mph? Where can I get the parts & how much?

[mdaspit]

Lester, compared to most on this site, I don't know squat... But.

If it's possible, it would have to be a "c mod" motor, and that means, a pipe, and a prop, absolute minimum.

Maybe too heavy for a Jupiter, and sit too high on that little boat.

75mph? Heck I know guys who would race it if it did that.

I love the look of those Jupiters.

Go to the top of this page and click on Search, and you'll find tons of stuff on mod-ing a 302.

If you do this... Post a picture, I want to see... And if you put it in the water, shoot video, we'll all want to see that!

[Lester Connor]

Jupiter

No luck with securing old rig I'm going to build a new one.
Any ideas as to historic modifications to the design and/or improved materials I could use? Any contacts to that end?
A couple of boats had their cockpits shifted forewards in the 60's here, one converted to a lie down - it was great in shifting the centre of gravity foreward & shifting more air rearward, but not ideal in circuit racing on rougher waters.

[johnsonm50]

Thats a pretty aggressive speed for an older design C hydro. In the upper 60s would be more likely with a 302 mod

[ZUL8TR]

No luck with securing old rig I'm going to build a new one.
Any ideas as to historic modifications to the design and/or improved materials I could use? Any contacts to that end?
A couple of boats had their cockpits shifted forewards in the 60's here, one converted to a lie down - it was great in shifting the centre of gravity foreward & shifting more air rearward, but not ideal in circuit racing on rougher waters.

Not clear, for the new one you want to build are you speaking about building the Jupiter design with updated mods?

Although Kelly states that his Jupiter was designed for B stock with the converted 20H and Hot Rod he also states it is for the A,B,C alky class with Konig and Anzani engines. I doubt that the Jupiter design at 9'10" and a short afterplane about 61" and a 33" bottom would be a safe place to be at 70+mph with the alky engines especially C class alky. The 302 could be a bit much for this hull and that will get to the high 60's and that would be on the edge.

[fcliff]

Easy bolt on

This is pretty easy bolt on.

[johnsonm50]

Nice thing about the Yamato's is the work has all been done, documented & is for sale. To go beyond that would make it an illegal motor to race unless you wanted to race pro. At that point the Stock Outboard Yamato's are too heavy & won't be fast enough.
If you wanted to upgrade the Jupiter by upscaling a little & maybe increasing the afterplane.. but then you don't have an origional copy or a sure to work setup. They were designed before the 302's time & I think it might be best to run a vintage correct motor on the Jupiter & or a modern C boat for the 302.