Avon SR4 with 25 HP - Would it work

[9D280]

Originally Posted by Mextli

i'm looking at the 4cyl Mercury 500 Thunderbolt, possibly with a Panther Power-Trim bracket to fit after trial-runs.

I did a lot of research to PT my clamshell. It MIGHT be possible with a swivel bracket from a 1990-ish Clamshell swap to fix the old 4 cyl onto a PT clamp/ swivel assy. I do remember the 4 cyl emgines being on my radar while I was investigating parts, so might be doable.

Other option is to find a couple of powered "external"rams. - you could use the Power pack off a mercruiser to feed them. The only down side would be the mass of hydraulic pipes on your transom. I had a plan where I was about to drill & tap the end fittings on the powered cyls to allow "off the shelf" hydraulic fittings to be used, along with modern flexibles. Idea being I could use smaller bore modern hoses & tee it off at the engine rather than run 4 hoses from the pump unit which I was going to fit under the seat.

But I tripped over the midsection that is now between my engine & hull before I got round to it!


If you want lightweight, the old 3 cyl "Clamshell" is likely about as light as you are going to get at that HP.

Originally Posted by Mextli

First i have to sell my old 25 hp though ...

Remind me, what flavour is your 25? Two lightweight 25s might be as heavy as some of the 50s out there. (50/60 was a favourite combination of de-rates, resultring in a fair few lardy 50s.) I looked at finding abnother Suz DT25 for mine, but they are the smallest HP form that hardware so was going to be waaaay too heavy. (75Kg / engione!) The old Johnson 25from 1972 clocks in at about 38KG......

An SR4 will still plane on 25HP. I know what size Aux I;d rather have!

[Mextli]

My trouble is i'm on a tight budget, and the 50 Thunderbolt is cheap and easy to get.

I might not even use powertrim in the end though.

[badbaws]

If you get a Tohatsu 40hp 2 stroke model 2 cylinders 40c (manual trim / tilt)
They weigh 62kg (on my scales) versus a Yamaha 25hp 2 stroke 2 cylinder which weighs 59kg on my scales.. extra 15hp for 3kg.. winner!
Now if a searider 4m could be specced with twin 25hp when new, and the weight difference between two 25hp yam and 2 40hp tohatsu is 6kg.. then how about a 4m searider with twin 40hp Tohatsu! now that would be fun!

[badbaws]

And just happes there are two such engines on ebay right now.. go on someone have a punt 4m and two x 40hp.. winner!

Ebay Item number: 130755256249 outboard motor engine tohatsu 40hp long shaft 2 stroke 2006 40c

Ebay Item number: 170900854236 Tohatsu 40 HP2 stroke Longshaft Outboard Engine 2003

[Mextli]

Let's just go the way a friend of mine went, put 85 mercury hp on it

[9D280]

Originally Posted by Mextli

My trouble is i'm on a tight budget, and the 50 Thunderbolt is cheap and easy to get.

I might not even use powertrim in the end though.

Seems like a good enough reason to go for one!

if you do go down that route, I'll see what I can dig up from my investigations. I guess it will have the outside rams, in which case swapping for the powered ones is realtively easy (sheared studs aside), you just need to be a little careful with the control system, as they have no "internal" way of knowing that the engine has just lifted clear of the clamp brackets, which means if you turn sharply with an open throttle you can shear the top of the bracket.
A simple switch on the clamps with an override so you can "full up" for beaches etc cures that

Like I say, if you don't mind extra hoses on your transom, Mercruiser leg power packs work with those rams (the smaller Mercrusier rams might also fit), so plenty of bits available used at low cost.

I think there is also an aftermarket replacement for the Thunderbolt ignition circuits which didn't always live up to it's name.....

[Mextli]

Originally Posted by 9D280

Like I say, if you don't mind extra hoses on your transom, Mercruiser leg power packs work with those rams (the smaller Mercrusier rams might also fit), so plenty of bits available used at low cost.

I don't

Your method sounds interesting - I'lll propably go that way.

Currently the price for the PT-Bracket is 600$ and that is alot of money ...

[Jonny H]

Just had a quick search and found these you would need to get a pump and motor as well of course

Mercury outboard power trim cylinders | eBay

Mercury outboard larger ram power trim cylinder Inline 4 & 6 cyl **10445** | eBay

[Mextli]

Thanks Prices don't seem too high...

Anyway, i'll get the boat repainted first, then get the motor

Plus the boat was painted with gummipaint, i have to get that off first

[Nos4r2]

Originally Posted by badbaws

And just happes there are two such engines on ebay right now.. go on someone have a punt 4m and two x 40hp.. winner!

Ebay Item number: 130755256249 outboard motor engine tohatsu 40hp long shaft 2 stroke 2006 40c

Ebay Item number: 170900854236 Tohatsu 40 HP2 stroke Longshaft Outboard Engine 2003

You'd need shorthafts though to compensate for the V.

[Downhilldai]

Originally Posted by Mextli

... I'll have the old set - up with the seats up front and the motor in the back

[9D280]

Originally Posted by Mextli

I don't

Your method sounds interesting - I'lll propably go that way.

Habve a look at the merc microfiches when you get round to it - memory says most of the powered rams from about 40-90 (ish) HP should fit as should the Alpha-1 leg rams.

Power packs - that's the easy bit!

Originally Posted by Mextli

Currently the price for the PT-Bracket is 600$ and that is alot of money ...

Yep. I bought a sizeable chunk of dead engine to strip it off!

[Mextli]

Now someone offered me a 40 HP Yamaha, at a reasonable price.

Is it possible to retrofit the powertrimm to those engines?

and, is it possible to use a Quicksilver Control unit with the yamaha?

[chewy]

PTT is nice but I wouldn't worry too much about it.
Me sliding back or forth on the seat of my SR4 used to adjust the trim enough to make a noticeable diffrence.

[Mextli]

I won't have a seat like that, "my" SR has the old Dashboard and 2-person seating up front.

[Downhilldai]

Originally Posted by Mextli

...and, is it possible to use a Quicksilver Control unit with the yamaha?

Yes, you can do so by using a pair of 'hybrid' control cables which have Merc connectors on the front and 33c connectors on the back. Commonly known as 'Mariner' cables, cos that's what was used as standard on Yam derived Mariners. The wiring loom would need to be adapted though.

[Mextli]

I have a mercury wiring loom and mercury control cable. I need 3m cable -
What do i have to do for the wiring loom or should i try and get a yamaha control set?

[Downhilldai]

Get a Yam control box.

[9D280]

Is it electric start? If so, and you have the dashboard version, simple to remove the old Merc Wiring / switches, and put them on your dash. Plenty of room to connect the cables behind there (they all use bullet connectors insde the box, regardless of make)

I am running a Merc on a Yam 703 control. Pulled the electrics & switches out the control, and from memory only had to change one connector from M to F on the loom (at the controls end) to plug it straight in.

I had to run a jumper to the anti start in gear switch that had to stay in the control box, but as I thougth it was also the best place for the deadman and with power trim retro-fitted, I used a short length of trailer lighting cable (7 core) and made up a loom for the 7 connections.

If you put the deadman on the console, you'll only need 2 cores to the ASIG switch.

If you are manual start, it's only a stop switch to worry about!


Removing the electrics also means when your box dies mechanically, you can replace it with pretty much any box! (they all use the same mechanism)

[Mextli]

I have all motor-concerned Electricitys inside the box - I'd love to keep the old one since its almost new

My motor is E-Start

So you say i have to remove all the Electric stuff from the box/get a dashboard starter key?