Mariner/yamaha 55. short shaft?

[Roflhat]

Does anyone know if the old yam/mariner 2cyl 55's came in short shaft?
Thinking about getting one as a project

[Davie]

Yes they did.

[Landlockedpirate]

Yep, as above.

Dad had one on a Mk1 Simms SuperV speed boat in the late 70's.

[A1an]

Great engine, very eager to hit maximum.

[Roflhat]

Cheers.

What about tiller control? I have a long shaft one here but I can't see how to change gear unless you were running cable control.

I'd need to adapt it for using on a thundercat

[Daniel]

You'll need the proper factory tiller kit, pretty rare now I would have thought

[RIB-Teccie]

If you go to crowley marine In the us. You will find the tiller online. They will be in the Mariner 48hp version. They sold these up to 1991 in the us and are still available. Prices are no different to a control box and costs 30 usd to ship. The 55 short shaft would have been around 1976 - 1978. Although the still made them for the 60d racing yamaha. If you are stuck, PM me and I will search the crowley website to find the right one.

[Roflhat]

Thanks for the help,

It would need an extended tiller anyway (the same as the tohatsu 50's get for thundercat racing). So I could probably just use any old tiller and mount it onto the extension.

Are the yam 60 2cyls the same as the 55s?

I've checked the gearbox off the one here and it's got the 1.84 ratio box. apparently you can get 1.71 gears for them, the same as the 70CES. Don't know where you get the gears though

[RIB-Teccie]

Yamaha 55 - bore/stroke 82x72mm & 13.24 gear ratio. Yamaha 60 - 84 x 72mm & 14.24 gear ratio. Engines are different. Yamaha 60d racer was different still and like hens teeth. I have one which was sold as 60d but is not, although the exhaust and one carb (factory bored) is. A1an on here has a mint 60 block if it helps and I have the sport exhaust. And one carb!! 60d revved out at 7000 rpm, I think!

[RIB-Teccie]

If you use a 55 gearbox with a 60 block, it will spin faster.

[RIB-Teccie]

The 60 gasket set does not fit the 55, it has a bigger water jacket and head gasket. Others are the same.

[RIB-Teccie]

Before you buy a 60block, it may be the 60d was the same bore as the 55. It was that age of engine. The carbs were bored out in an offset way. I think it would be too much for a zapcat though, they were a pure racer for lakes. A stock 60 with a 55 box would be interesting.

[Roflhat]

Thanks RIB-Teccie, this is great information.

I'd not heard of the 60d, must be very rare. I know the 70CES is very sought after, although I think it's a bit heavy for a thundercat.

It seems to me I want the 60 gearbox? which will give higher top speed but less acceleration.
Think the hard part is finding a short shaft one with the 1.71 (14:24) ratio gearbox.
Not much point changing to a 1.84 gearbox, the one on my tohatsu 50 is 1.85 and I'll be able to spin it to over 7000rpm.
Think the 55's use the same props as well, 13 spline.

I don't think you can have too much power on a thundercat, as long as the engine is light enough.

Is yours short shaft?

[RIB-Teccie]

I have various yam 55 & 60 parts, but not in short shaft. They do come up on eBay as 55ae short shaft yams. The problem is a the racers are still after them and you pay a premium for something very old and hard to break down. The 55 won't come with the 60 box you are after. The shaft is not too hard to replace and you may find what you need on the crowley site. There's no easy answers for your project I'm afraid.

[Roflhat]

Ah right ok. I'll keep an eye out on ebay.
I'll stick to the tohatsu 50 for now.

[RIB-Teccie]

There's a short shaft on eBay now. Trouble is there's a boat attached!!

291151494436

[Roflhat]

Haha!
Even with the boat it's cheaper than a used tohatsu 50

[RIB-Teccie]

You will probably find out why wham you try to strip it down, they can be pigs if the bolts are seized. On the plus side if they do come apart and your willing to spend, you get a cracking engine.