Engine for 5.4 searider

[deeja]

From what I've read, the conventional 90hp yamaha seems to be a popular engine for the Searider 5.4.
If I was going to buy a new engine, would this still be the best choice or are the four strokes going to be much more fuel efficient (although heavier)?
I'd be interested in any opinions.
Cheers

[jeffstevens763@g]

hi mate

i had a brand new 60 yam on my fast fisher brilliant engine,
i now have a 90 Suzuki on my rib again brilliant engine,
but would choose the Suzuki over the yam because the yam has a timing belt the Suzuki has a chain in an oil bath personnel preference only.

regards jeff

[deeja]

Cheers for the reply Jeff
I guess yours are both 4 stroke?

[whisper]

The new Yam F70 weighs 117kg however the F75 & F90 weigh 166kg

That's a lot more weight for only 15-20hp more power.

I'm not sure how well it would go with a 70 but you may find the 90 will be a bit on the heavy side?

Hope that helps

[JamesF]

The new Yam F70 weighs 117kg however the F75 & F90 weigh 166kg

Mercury's 75hp and 90hp four-strokes are 163kg; Evinrude's 75hp and 90hp E-Tecs are 145kg; Suzuki's 70hp and 90hp engines are 155kg.

Yamaha seem to have done really well on the weight of the F70. That's only 7kg more than a 25hp we used to have!

[jeffstevens763@g]

your right both engines four stroke my 90 is on a 6m rib i usually carry loads of kit and 140 ltrs of fuel and still get 35-45 mph out of her at WOT she will plane at 20 mph in most sea conditions [that you are able to plain]that amount of fuel gives me around 160 mile range my engine is a 2009 the new ones are lean burn good bit better on fuel.

regards jeff

[RIB-Teccie]

The 5.4m Searider is a strange one. Most manufacturers reduced the horsepower ratings on their transforms to reflect the weight of the four stroke engines. The thinking became more about how much weight was on the back rather than the Horsepower. A Rib that would take a 70 was reduced to 60 and so on. It may be an idea to find out what is recommended for the avon currently for insurance porpoises. My choice would always be a 90 Yam used followed by the equivalent weight Etec if I was going for new. Four Strokes are fine for heavy hours if you are going to do anything like 700 - 1000 hours per year. If not, why deny yourself the power to weight ratio (and ease of maintenance) of the two stroke. There are quite a few on here that can give accurate fuel comparisons between similar two and four strokes.

[matt h]

As said the 90 two stroke yam is by far the best choice. Ive got a 4.7 mod SR and taken the plunge on a new F70 as the weights is 12 kgs under the transom weight and rated to 70 also so hoping this will give me 40 kts. The SR 54 really needs a 90 and weighing in at no more than 140 kgs to give a good balanced ride

[JamesF]

The Zodiac Mil-Pro website is currently recommending 80hp for an SR5.4, but it doesn't look like a maximum, just a recommendation.

As far as I know, only Suzuki and Honda make a 80hp motors, and they're both about the same weight as their 90s. The other manufacturers seem to prefer 75hp, and they all seem to be the same weight as their 90s as well.

As far as power–weight goes:

Yamaha 90AETOL 2-stroke: 90 ÷ 120 = 0.75 hp/kg

Yamaha F70: 70 ÷ 117 = 0.60 hp/kg
Yamaha F90: 90 ÷ 166 = 0.54 hp/kg

E-Tec 60: 60 ÷ 109 = 0.55 hp/kg (the nearest to the Yamaha two-stroke for weight)
E-Tec 90: 90 ÷ 145 = 0.62 hp/kg

So the 60hp E-Tec isn't really all that good for power/weight, but the 90 is the nearest thing to the Yamaha 2-stroke (25kg weight penalty), which you can't get new for leisure use nowadays anyway.

So if 90hp is an absolute 'must', the E-Tec 90 has it, but if the extra 25kg is too much, Whisper's suggestion of the F70 looks better.

Not that power and weight are everything, of course .

[deeja]

Thanks for all the advice.
So from what I understand, it sounds like the 2-stroke 90 Yam is the one to go for - due to the much lower weight. As I won't be doing large numbers of hours, it doesn’t sound like the increased fuel efficiency of a 4-stroke will also be too much of a factor - this will also be partially offset by the reduced cost of a 2 stroke. Luckily the RCD does not apply here (Channel Islands) so we can still legally buy 2-strokes.
Thanks

[RIB-Teccie]

You can still legally buy two strokes!!! You can go off people you know!!! By the way, if that's the case, if you find a good one, don't pass up an 85 Yam.

[camelgas]

On which Island can you still buy a new 2 stroke ? , and do the dealers still stock them ?.

[deeja]

I live in Jersey but I suspect it will be true for all the Islands. As we're not part of the EU or UK, we are only governed by Jersey law which means dealers in the UK who legally supply 2 strokes for UK commercial customers can also ship here to residents. The shipping costs are quite high, but goods are zero rated for VAT which offsets that (although GST is payable on any imports over about £250 which is currently 5%) . It would of course be illegal to sell it back into the UK.

I suspect the local dealers can probably supply them, but it's usually cheaper to import most things from the UK yourself.

[benjytaylor]

I wouldn't look past an opti 75 or 90. Big engine but great on fuel and all the power in the world. I feel hydrolic steering is a must if you are going to bolt a large carbed 4s or opti on, or the craft will be twitchy at wot.

Having said that, if you can find a nice second hand honda 75/90 they are a great engine on a searider.

I've been through a yamaha 75 pro 2s, yamaha 80 2s, yammie 90 2s, they all give like for like performance with a 17P SS prop.
I've also had carbed 4s merc and mariner 75's, a wee bit heavy but good on the juice. Watch out for big end bearing going on them. (There is a nice cheap one on fleebay for £2250 item number - 261629467158)
I've had a twatsoo 90 2s that was good lump but thirsty like the yammies.
I've had a Suzuki 90 4s efi. Good engine but seriously heavy!! About 185kg. Not as good as the opti on fuel.
The opti is a nice unit but can be expensive to service or repair and is full of electrics.
Never had an etec

[benjytaylor]

A few of the other lumps and the current opti before I upgraded to modern 4s 😏

[Searider]

Had a 90hp Mariner 2 stroke on my Searider. 40ish knots with a 20" ss prop.
Good match for the boat - as others have said look to fit the lightest motor possible. The Searider is a really narrow hull and doesn't like weight.
I had simple cable steering and didn't feel the need for hydraulic.
Honda 75/90 and opti 75/90 heavy engines I think.

If you can buy a new yamaha 90 2 stroke I'd go for it. Will BHG in Lymington supply.
Let us know the cost if you go ahead.

[deeja]

For those that are interested, i've had two quotes - both just over 5k (ex VAT)

[jeffstevens763@g]

Some good info here but for me go to the top on hp for your boat you have plenty of scope then you can always throttle back less work for the engine carry that bit more kit etc no two days are the same.
Good luck with your choice

Regards Jeff