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07.06.2021 2:32:30
Re: Yamaha 90hp 2-Stroke please help us [links]
See full version: Yamaha 90hp 2-Stroke
Re: Yamaha 90hp 2-Stroke please help us [links]
Thanks for the responses. If I buy one I'll leave the "oiler" alone. I really like the idea of an inline 3 cylinder as a 90 hp. My Johnson 65 is a great motor but those few extra horses would be nice and I wouldn't have to move the kicker off of the transom, as I would with a V-4. Only problem is that I would have to go find a kicker that doesn't use premix fuel! If only Briggs & Straton would make their air cooled 4-strokes salt water compatible! more
we have a 1990 90 hp yamaha we want to remove the vro how do we do this? we like pre-mix fuel here
THe blocker plate is all you need to do.My old 115merc I looped the oil hose just to circulate around the pump and It ran for years like that.The lower unit blew but he motor didnt. [links]
Does anyone know how much oil to put in vro plastic jug on side of motor?We had oil running out cap with wires,and just kept running.
My Navman with fuel sensor reports I get around 1.2 Nm per Litre at cruising speed. Economy is pretty linear with respect to speed upto around 4000 RPM. After that it starts to fall off to around 0.9 Nm/L. here
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What is the difference in fuel economy between a fuel injected 2 stroke and a carbed 2 stroke. I know a carbed engine will be more but how much more in terms in litres per hour. Also has anybody got any fuel figures of a 90hp on a 5-6m rib at crusing speed of the two types to compare. And what do people think are the best makes/models engines out of the two categories to buy second hand around 2-4 years old. To help in a possible future purchase.
Mercury 90 classic 2 stroke carb on 5.5m Delta, 2 up, full tank and some gear.
I run a standard 19" ally prop and max out at 5000RPM = 33Kn light load. [links]
Hi ,
Thanks for quick respond !
This is what confuses me - I could not go at all with WOT - but the oil consumption is even higher than going full time with full speed !
I wonder how much oil I will burn when I really go with WOT ! here
Hi folks ,
After I solved the issue with my stator my 90hp works very well .
I was with my RIB on a sea trial today and burned 45 liters of fuel . Due to rough sea conditions I was mostly at 3500 rpm only .
Back at home I checked the oil tank and added exactly 1 liter of 2 stroke oil .
This is my first 2 stroke engine and thats why my question - is a 1:45 mixture normal for this motor .
My tank has a capacity of 90 liter - means I`ll need 2 liters of oil per tank !!
Fuel consumtion was about 0.5l / km . My F100A on another boat takes about the same .
Would appreciate to hear about the experience of other 90hp users !
Thanks in advance !
Hi Rodbolt & thanks for your comments !
Actually all I have done was to adjust the linkage to the oil pump according workshop manual . The setting before was the the stopper was reached long before the throttle was 100% open .
This resulted in tension respectively in deforming / stretching of the connection rod from the carbs to the oil pump when the the oil pump was at the stop already but I pushed the lever to maximum speed .
With extending the control lever by appr 4mm the setting now is that with full open throttle the lever of the oil pump is at the stop - but without force .
With this setting I went for a long trip and calculated afterwards a oil consumption of 1 part oil to 60 parts of petrol = 1 : 60 .
BTW - I used Putoline syntetic oil and do not think I did any damagage to the engine ..
The sea conditions did not allow me to go with more than 3500 - 4000 rpm .
Most of time I went with 3800 rpm .
What is your opinion ?
[links]
In normal use, a range of engine speeds would be used, so my guess is that the differences between the mid- and high-range consumption figures would cancel out, and there would hardly be any difference between the two. If both engines are used at WOT continuously however, it would seem that the two-stroke might be even more efficient than the four-stroke!
I know that it is not much of a sample with just two engines, and also the weight of the boats used in the Honda tests seem to have been slightly heavier than those used in the Optimax ones, but I was just wondering if other forumites have found this in practice? here
Up to about 3000 RPM there is very little difference between the two types of engine. Between about 3000-4000 RPM, it looks like the four-stroke consumes a bit less than the two-stroke, but at higher revs above 4000 RPM, the two-stroke is using less than the four-stroke.
In normal use, a range of engine speeds would be used, so my guess is that the differences between the mid- and high-range consumption figures would cancel out, and there would hardly be any difference between the two. If both engines are used at WOT continuously however, it would seem that the two-stroke might be even more efficient than the four-stroke!
Up to about 3000 RPM there is very little difference between the two types of engine. Between about 3000-4000 RPM, it looks like the four-stroke consumes a bit less than the two-stroke, but at higher revs above 4000 RPM, the two-stroke is using less than the four-stroke.
We always hear that four-stroke outboards are much more fuel efficient that two-strokes, but are they? I have been doing a little bit of research to see how the more modern 2-strokes compare to 4-strokes. I gathered performance data on two engines – a Mariner Optimax 75 hp (two-stroke) and a Honda BF75 (four-stroke) from the web-sites of the manufacturers (I chose the Optimax because that is what we have on our boat). The graph below shows the fuel consumption figures for those engines with a range of boats – red ones for the Optimax, blue ones for the Honda. (Note that this is fuel consumption, the inverse of fuel efficiency.) here
In cases where there is a fair and somewhat equal comparison done, I have not found there to be much more than 25% in fuel saving with 4 stroke and in many cases less. For example Chero's 4 stroke 115 figures above are not that far better than a 2 stroke 90 I had on the same hull as Chero. My older boat, a 1990 DE 17 hull with a 1997 90 hp Johnson carbed 2 stroke would run at about 25 mph and consume about 3.5 gallons. At 32 mph almost 6 gals/hour. Although not the same hp, in this comparison the 2012 merc 115 4 stroke compared to the 1990 carbed 90 hp 2 stroke the actual fuel consumption difference is barely 10% ( not counting oil consumption)
Supposedly you can expect up to 30% better fuel economy with the newer motors. Would be interested to hear if anyone has a similar boat to ours with a newer 4 stroke or ETEC.
Interesting, I have almost exactly the same fuel economy on my boat. more
1993 Hourston 17' with a 1993 Johnson 70hp two stroke. My last trip I went 86 miles, cruising around 25mph and burned 76 litres. That miles though, not nautical miles. [links]
Meanwhile Leftcoast got 1.15 l/nm with a 150hp etec on the same boat, probably averaging slightly faster speeds.
Meanwhile Leftcoast got 1.15 l/nm with a 150hp etec on the same boat, probably averaging slightly faster speeds. here