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