Yamaha VF250 SHO Short Shaft Build Thread

**InjectorService** · 04-03-2023, 03:41 PM

I wanted to share with you all a project that I have been working on. A couple years back I had purchased a Yamaha 250SHO, with the intent of playing with it and turning it into something unique. Today, I can tell you it has made some great progress and should be well on its way to becoming complete.

The largest portion of this project was cutting a little over 4" out of the midsection. The mid starts out as 16 7/8", and is now 12 3/4". All this is done while retaining very similar to the factory oil capacity of 6L. On a typical 2-stroke, this is a much more manageable task, but factoring oil flow, the oil sump itself, water & exhaust all into one unit was not quite so straight forward.

Some other stuff we are doing to it includes solid mounts, brass bushings all around.

As far as I can see, this is the first time someone has done this to a Yamaha 4.2L, in fact I can't actually find any 4-stroke that has had the mid-section shortened in the same fashion. Hopefully this work will be done soon, and I can get to installing the re-freshed powerhead, and cleaning up a bunch of the factory "junk" under the cowl.

All of the custom fab work credit goes to a gentleman of the name Derek Lord (Instagram @Hydrostream _rebuilds), he has been a pleasure to deal with, if you are in Canada and need some work done, I highly recommend you speak to him.

**oldschoolltv** · 04-03-2023, 05:27 PM

Subscribed. Nice work.

**Instigator** · 04-03-2023, 06:19 PM

I like it.

There is a bunch of fans of that motor.

Please keep us posted.

**CharlieN** · 04-04-2023, 08:39 AM

Very nice,
As a welder/fabricator who is not afraid to climb out of the box I find it rewarding to see someone undertake a task like this.
Is the shaft on that engine necked down or full diameter allowing for an easy re-spline?

**canuckr** · 04-04-2023, 08:53 AM

Charlie.
It's necked down. It will be cut and welded.
I've only run across 1 Yamaha driveshaft that's not necked down. And it's ironically on a chopped down V4 I did for the wife's Viper.

**InjectorService** · 04-04-2023, 09:19 PM

Some CAD design on the snout.

Exhaust

Final product (end cap will come off, it's just there to keep everything straight)

**oldschoolltv** · 04-05-2023, 04:52 PM

Looking good what boat will this go on?

**Greg G** · 04-06-2023, 06:15 AM

Subscribed. Very cool.

**DrexelSST** · 04-06-2023, 11:47 AM

This is awesome! I am going to be putting a Yamaha SHO on my 1980 Sleekcraft and would love to have a shorter shaft on it.

**InjectorService** · 04-06-2023, 08:21 PM

Unfortunately I don't have a hull yet. The long-term goal would be to get one of the following hulls and supercharge the Yamaha.

1. Talon 22
2. Liberator 22 (maybe 21 if the price is right)
3. Cougar 21 (if the price is right)

I'm also considering leaving it with no supercharger and running it on a STV Euro. But I'd have to confirm the weight beforehand. Guys are running HPDIs and Optimaxes at around 500lb, but this is probably a bit heavier.

This is sort of a premature project, but Derek presented me the opportunity and I couldn't say no.

**canuckr** · 04-07-2023, 03:34 PM

Originally Posted by DrexelSST

This is awesome! I am going to be putting a Yamaha SHO on my 1980 Sleekcraft and would love to have a shorter shaft on it.

Take it apart. Throw it on a pallet and stick it in the mail.

**InjectorService** · 04-08-2023, 02:28 PM

A little more snout work now that Derek is done shoveling the snow.....

**MarineX** · 04-14-2023, 05:02 PM

Hey Injector, I am a buddy of D lords, been cool going over to his shop and see this unfold, and keeping it hush hush! Lol

**tnelsmn** · 04-14-2023, 08:51 PM

Originally Posted by MarineX

Hey Injector, I am a buddy of D lords, been cool going over to his shop and see this unfold, and keeping it hush hush! Lol

The project is no longer under wraps!

**InjectorService** · 04-15-2023, 12:22 PM

Originally Posted by MarineX

Hey Injector, I am a buddy of D lords, been cool going over to his shop and see this unfold, and keeping it hush hush! Lol

Your lucky, I wish I lived closer. It's been killing me not seeing it in person.

It sounds like the midsection will be shipped back to me maybe later this week. Then off to powder, getting bronze bushings installed, the chaps and lower unit will be sent later. I think the driveshaft has been cut and welded already as well.

I'm hoping Derek can do the lower the way I want, should turn out pretty sweet if that's possible.