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Old 07 October 2014, 11:09   #11
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 886
The yam 90 is surprisingly "economical" considering its a carbed 2 stroke. The WOT consumption, low to mid thirties l/h is not far off compared to modern engines
(off course the difference is there at lower speeds).

Power to consumption wise, possible its one of the best designed old style 2 stroke outboards ever made, cant recalling test figures of any other outboard as good.

Economical is maybe not the correct word but in its league its very good.

fun on a boat is inversely proportional to size...sort of anyway
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Old 07 October 2014, 11:12   #12
Country: Ireland
Town: Castlebar
Boat name: Clewless
Make: Valiant DR 490
Length: 4m +
Engine: 60 hp ETEC
MMSI: Awaitng one
Join Date: Oct 2007
Posts: 1,118
you should bear in mind there is more costs to running an OBM than filling it with petrol, keep an eye on the cost of keeping it running


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Old 07 October 2014, 11:40   #13
Country: UK - Wales
Town: Cardiff
Make: Avon
Length: 3m +
Engine: 2 stroke
Join Date: Aug 2014
Posts: 487
I love 2 strokes but if i was spending money then it would be on a proven reliable 4 stroke with low hours and good maintenance record. There is a lifespan to all things mechanical and 20+ year old motors are not in the first flush of youth.

The Etec type motors are supposed to be very good on fuel, it depends on usage, your dropping HP (alright your 115 is probably closer to 100 now but an older 75 may be at 60 or less) and you might find your running higher revs to compensate, less torque, smaller prop etc. Higher revs burns more fuel so unless your current motor has blown something big and expensive then your spending money to save ??? if your looking at a straight swap then you might save some fuel but is it worth the faff?
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Old 07 October 2014, 11:47   #14
Country: UK - England
Town: Plymouth
Make: Fletcher 160
Length: 4m +
Engine: Mercury
Join Date: Aug 2014
Posts: 6
I have a 1989 3 cyl mercury 80 & cruising at 4000 rpm, 24kts with some WOT bursts I average 1.35 nm per litre.
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Old 07 October 2014, 12:43   #15
Country: Germany
Town: Kiev
Boat name: Black Hawk
Make: OSPREY Vipermax 7m
Length: 7m +
Engine: ETEC 250
MMSI: 211579640
Join Date: Aug 2009
Posts: 389
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Originally Posted by C-NUMB View Post
The yam 90 is surprisingly "economical" considering its a carbed 2 stroke. The WOT consumption, low to mid thirties l/h is not far off compared to modern engines
Had the 90 Yam on my Searider and used 0.5l/km .
On the same boat I installed later an ETEC 90 - some of you may be remember the boat from the Round Ireland - where I used with the ETEC 0.44l/km .
So I would consider the Yam 90 as quite economical .
For the difference to a more expensive motor you can pay for a long time your fuel bills .
The problem with the Yam 90 - it is harder and harder to find a good one ..

BTW - my Yam F100 4 stroke uses on another boat also exactly 0.5l/km ...
ETEC - each stroke is a power stroke
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Old 07 October 2014, 13:58   #16
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Country: UK - England
Town: Bristol
Boat name: Red Alert
Make: Tohatsu One Design
Length: 6m +
Engine: Mercury 125hp
Join Date: Sep 2014
Posts: 97
So the yam 90 is economical compared to the yam 115 but old and hard to find a good one.

That helps as the chap I bought the rib from has offered me the yam 90 that was originally on the boat, it had broken so he he gave it to somebody to rebuild and its nearly ready. I suppose its worth taking a chance if the price is right.

Also the rib is only rated to a 90hp and as somebody said there could be problems with insurance if i leave the 115 on.

Thanks everyone

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