Mercury 90 4 Stroke.

[Hightower]

Anyone give me info on the above (circ. 2000), ie: max fuel usage at WOT, reliability and if there is an online manual that I can use?

Andy

[philip]

Originally Posted by Hightower

online manual that I can use?

Andy

Tue had some real paper workshop manuals for £15 :

http://www.rib.net/forum/showthread.php?t=3891

Cheers

Phil

[tue]

We have one on our dive club RIB and its fantastic. I can't give you fuel figures as we never worked it out but it doesn't use masses.

Reliability wise we have clocked up about 750hrs in the 3 years we've had it and we have had no problems with it at all. It gets hammered at full throttle where ever they drive it and is usually well over the top exhast outlet in water when they fill the boat with divers and it just keeps running.

The only thing I would suggest is getting hydraulic steering if its not allready fitted, as it is a heavy beast to turn and even with the No Feed Back helm it is hard to turn and keep in a straight line.

[DJL]

Hi Andy,

You can download the standard manual from www.marinepower.com

[DM]

I ran one of these for most of this season. Excellent fuel consumption, but Tue is right. It is a heavy lump for its output. It might be worth considering the extra weight over the Yamaha 80, assuming it's for your BWM.

I also found the gear selection to be a bit clunky, more so with a S/S prop on.

DM

[Bilge Rat]

Originally Posted by davidmanning

I ran one of these for most of this season. Excellent fuel consumption, but Tue is right. It is a heavy lump for its output. It might be worth considering the extra weight over the Yamaha 80, assuming it's for your BWM.

I also found the gear selection to be a bit clunky, more so with a S/S prop on.

DM

No Dave the Yam 80 is a heavy old lump too, its 30 ish Kg heavier than the 60 Yam, in this case i'd suggest there wouldn't be that much difference between the Yam 80 and the 90 merc weight wise.

Lord D will know doubt be able to give us the accurate figures

[tue]

We are talking 90 fourstoke. So V heavy lump

[DM]

Originally Posted by Bilge Rat

in this case i'd suggest there wouldn't be that much difference between the Yam 80 and the 90 merc weight wise.

My understanding is that the Yamaha AETOL eighty is a twostroke with a weight of approx 120kg. The Merc four stroke is about 180kg. That's enough weight difference hanging outside the transom of a sub 6M boat to turn it from a sweet handling set up into a dog. Add in the fact that the Merc is a taller engine which will alter the C of G.

DM

[Searider]

Jools on Panther has one of these on his Ribcraft 585.

He used about the same amount of fuel at cruising speeds on the BIBOA SW cruise as my 90hp 2 stroke did on my 5.4 Seraider - a bit under 1 litre per mile, say about 0.9l / mile.
Made me feel very smug

Dont forget the 90 four stroke is on carbs and so is not going to be the best on fuel consumption.

Out of interest the 150hp Optimax on my 6.5 Scorpion also uses just under a litre per mile.

Not sure how much / little the 4 stroke would use at WOT

[Bilge Rat]

Originally Posted by davidmanning

My understanding is that the Yamaha AETOL eighty is a twostroke with a weight of approx 120kg. The Merc four stroke is about 180kg. That's enough weight difference hanging outside the transom of a sub 6M boat to turn it from a sweet handling set up into a dog. Add in the fact that the Merc is a taller engine which will alter the C of G.

DM

Ah ha now i thought we were talking about 4 stroke not 2 stroke, this does change things somewhat doesn't it

[Hightower]

Yes I am concidering the Merc 90 to replace the 80 Yam I have. Nothing wrong with the Yam, but it is quite old and wouldn't feel 100% happy without an Aux outboard strapped to the transom, which is exactly what I've been doing.

I like the Idea that I'll have a much newer outboard and wouldn't need an Aux.

The Yam weighs 135kg according to my manual and from what I can make out the Merc weighs in at 175kg, so is 40kg going to make that much difference! Have to remember that the Auxillary won't be aboard and neither the fuel tank for it. I will end up with a heavier steering I suppose and I will stick to good old cable type untill it needs replacing.

I am buying purly on the fact it's a newer outboard than I have currently and If I get better fuel consumption, great! Should also be able to cruise around the harbours better that with the Yam as it never felt comfortable on low revs.

Budget wise it's tight and I guess there's always a risk of buying the wrong outboard for your boat combo. But we are all in the same boat when buying a hull/engine outfit.

Incidently, didn't Daniel have a 130 Yam V4 on the back of his BWM Deepsea 18, that must have weighed in pretty heavy.

Thanks DJL, I'll have a look.

Andy

[Bilge Rat]

Originally Posted by Hightower

Yes I am concidering the Merc 90 to replace the 80 Yam I have. Nothing wrong with the Yam, but it is quite old and wouldn't feel 100% happy without an Aux outboard strapped to the transom, which is exactly what I've been doing.

I like the Idea that I'll have a much newer outboard and wouldn't need an Aux.

The Yam weighs 135kg according to my manual and from what I can make out the Merc weighs in at 175kg, so is 40kg going to make that much difference! Have to remember that the Auxillary won't be aboard and neither the fuel tank for it. I will end up with a heavier steering I suppose and I will stick to good old cable type untill it needs replacing.

I am buying purly on the fact it's a newer outboard than I have currently and If I get better fuel consumption, great! Should also be able to cruise around the harbours better that with the Yam as it never felt comfortable on low revs.

Budget wise it's tight and I guess there's always a risk of buying the wrong outboard for your boat combo. But we are all in the same boat when buying a hull/engine outfit.

Incidently, didn't Daniel have a 130 Yam V4 on the back of his BWM Deepsea 18, that must have weighed in pretty heavy.

Thanks DJL, I'll have a look.

Andy

Andy....Am i correct in thinking your intending to switch from 2 stroke to 4

I changed my engine back in September from 2 -4 stroke and wish i'd done it ages ago, the 4 stroke is brilliant, its efficent and you can have a conversation with others without having to shout at each other, i'm now considering fitting a sterio as its so quiet on the boat

I cant vouch for the Mercs but will say people seem to have trouble obtaining parts and parts on order seem to take ages to arrive, Yamaha on the other hand seem to have got the dealer networks right, parts seem easier to obtain if your in a hurry.

Good luck with whatever you go for

Richard

[Hightower]

Yes Richard, you are right.

Arn't Mercury's and Mariner's basicly the same engine?

[DM]

Originally Posted by Bilge Rat

Andy....Am i correct in thinking your intending to switch from 2 stroke to 4

Rat, there's a clue in the first line of his penultimate post.

Daniel did have a 130 V4 on his BWM. Weight 167kg, with more power snap and lower centre of gravity than a Merc 4 stroke of equivalent power.

Weight outside of the transom is critical to the balance/handling of a boat(more so in rough seas).


DM

[Rogue Wave]

Originally Posted by davidmanning

Rat, there's a clue in the first line of his last post.


DM

You leave Ratty alone hes a good bloke apart from having a 4 stroke!

[timboli]

Hightower,Come and have a play in my boat if you like(after 7/1),the yam is slightly lighter then the merc(167kg dry),and the weight on the back of my 5.7 (which is quite narrow but the tubes extend behind the transom a fair way)seems fine.
The yamahas seem a bit more expensive but it may be useful for you to try it.

[tue]

Originally Posted by Hightower

Yes Richard, you are right.

Arn't Mercury's and Mariner's basicly the same engine?

They are exactly the same engine . Except the Mariner has a a silver hood

[Daniel TD5]

high tower

ive just changed my mariner 40hp two stroke to the mercury 50hp which is a jump of over 300cc and a new cylinder to go with the other two and i would say thats the biggest two stroke i could afford to run apart from carrying fuel

as bilge rat said the parts are a real pain i waited two weeks for a trim tab which should be a service part as it an anode as well the bolt that fitted it took two weeks back order which can be a pain

my wish list would be four stroke but the most important would be EFi
no carbs as most of the running probs on this forum are down to carbs it seems. i think the mecury and mariner brands are very good and i think barrus
is down your way which are the importers you could go direct to pick up parts

good luck

dan

[Hightower]

Timboli, thanks for the offer. Might take you up on that trip! I am going to buy, but cannot get my hands on it untill end of Jan when it is replaced by a 150hp Optimax.

Daniel, I am aware that there is some supply and demand probs with Marina/Mercury, but customers always seem to get bits in the end. This motor has carbs and not the more desirable EFI.

[Daniel TD5]

andy

if its been well serviced it will be ok try seeing if you can get a ex boat show
engine my old mariner 40hp was a valiant display model and was very cheap
it just was fitted to a rib for two weeks for display then sold off cheap


dan