CONTINUOUSWAVE

I recently acquired a 1989 Outrage 18 with the original 1989 Johnson 120-HP outboard engine. The wide-open-throttle operating range is 5,000 to 6,000-RPM. The engine came with what I believe was the original 14 x 17 aluminum propeller. It was a little beat up and the hub was spun, so I replaced with a new standard OMC 13.25 x 17 aluminum propeller. On flat calm water with only me and minimal gear (say, 300-lbs combined), one-third tank of fuel, and with the motor trimmed out a ways, I am able to reach WOT 4800-RPM and about 30-MPH (per the GPS on phone). With the same setup, I would like to be at about 5,800-RPM.

The previous owner reported that he recently was able to reach WOT engine speed of 5,500-RPM with three adults on the boat and a light fuel load. That was with the old propeller, and he observed some hub spin out of the hole (and possibly at WOT). The engine, except for the occasional stall when cold at about 700-RPM idle (which I view as normal for this vintage 2 stroke), runs and sounds good to my untrained ear. When it does stall, it immediately starts back up with no problem. I can get on plane in five seconds and haven’t noticed any major burps, hiccups, stumbling or hesitation.

I have done a lot of what I consider regular maintenance items: repainted bottom, installed and tested new properly gapped plugs, drained and replaced lower unit lube, replaced tank-to-motor fuel line and primer bulb, replaced fuel-water separator, inspected outside of carburetors visually for gum and varnish and full venturi opening at WOT position, primed bulb with carb cover off to check for leaks, etc. There was an air leak in the fuel line that has been remedied. There was also some fuel in the bottom of the carburetor cover that, for whatever reason, had not been sucked up into the crankcase. (This causes me to worry about vacuum problems, but the opening in that pickup hose was tucked firmly against the cover, so might have been obstructed.) At least two of the four carburetor bowl drain plugs -- which cover the high speed orifices -- had been cross threaded and may have been leaking fuel, but that too has been remedied. None of this has had any effect on my WOT RPM or speed.

My next step (which probably should have been my first) is to run from an on-deck 6 gallon tank and see if I notice any change. If I do, at least I will know I have a fuel supply concern.

There are myriad possible reasons for WOT RPM loss, but before I get serious and start rebuilding carburetors, testing coils and power packs, and inspecting the fuel pickup in the tank, I would like to know whether this is the type of performance I should expect with the propeller I now have. I will say that there are layers upon layers of bottom paint that tend to keep chipping off, which I’m sure creates some measure of drag. But it seems strange to me that a 120-HP engine would have a tough time swinging a 17-pitch propeller on a fairly light hull. (Water intrusion is not one of my concerns at this point.) Then again, the engine was rated a 120 at the flywheel in 1989. I wouldn’t be surprised if, 27 years later, it was only putting out 90 hp (or less) at the prop. Has anyone had a similar setup with comparable numbers or experienced similar problems? Do I simply need to find a 15 or even 13 pitch propeller for this motor?

Here’s the rub. The hull in in very good condition, so I plan to repower soon with a new E-TEC--I can’t aesthetically justify the Gen II look on a classic hull--or possibly a Mercury 150 Fourstroke (I guess they don’t make the 150 Verado anymore). So I don’t want to waste precious time and money late in the season. At the same time, I want this engine putting out as much power as I would think it should be for the next three months, before I strip the bottom and repower. Thanks in advance for your thoughts. (I will start another thread soon so you all can debate my new motor choice.)

Maybe you are only running on three cylinders. Check that each cylinder is firing by pulling off the spark plug leads, one at a time. Engine speed should drop when you pull the spark lead, if that cylinder was actually firing.

That engine was rated 120 HP at the propeller shaft. If in good working order, it should push the boat to 40+ MPH. Have you done a compression check? If I recall correctly, the compression on the motor should be in the 120 to 130 psi range (gauges will vary).

Regarding repower, a 150 E-TEC G1 is a no brainer on the Outrage 18.

Thanks, both, for your replies and apologies for the delay. After tinkering a bit further, I decided now was a good time to just repower with a new 150 E-TEC G1. BRP had a decent promotion and I got a pretty good price from my local dealer. I chose not to go with the "H.O." model because the specs are identical at the 150 hp level and no one could give me a good enough reason to do otherwise. I also chose not to go with the G2 because it's a bit heavier, due largely to the new mounting bracket (which apparently can be swapped out for the traditional bracket), and I just couldn't envision it aesthetically sitting on my transom. I chose the standard analog gauges, but added a SIMRAD NNS7 evo2 connected to the motor via a NMEA 2000 backbone for digital details.

So far top speed is 44-45 mph (GPS) with standard 14.25x17" aluminum prop, 60 gallons of gas (370 lbs.), general gear (about 100 lbs.), and one operator (about 160 lbs.). I am also still in the initial phase where the motor really drinks up the XD-100, so the gasoline:oil ratio should improve. My time to plane can be measured in fractions of a second. The motor is mounted one hole up, which seems okay with this prop, especially in higher-speed turns when trimmed out, but suggestions as to re-mounting and re-propping are welcome. It is very, very quiet at idle. I've used it for only a few hours, but so far I am very pleased with the performance of this motor.

To respond to your specific questions, be they now somewhat moot: Jim, all cylinders on the old 1989 Johnson 120 hp were firing, though I cannot confirm that all of the ignition coils were putting out enough juice at high RPMs or that all of the high speed orifices were clean. Peter, you were correct that the old motor was rated to put out 120 hp at the shaft; I had my years confused. Compression in the lowest testing cylinder is at 100 psi; in the highest testing cylinder it's at 125 psi. This is just barely acceptable under the manufacturer's twice-revised 80 percent standard. The cylinder walls looked okay, so a new cylinder head gasket and/or ring replacement might have remedied the problem. The plug in that cylinder had a tendency to oil foul. In any case, I suppose that motor is now for sale.

Thanks for the update and the images of the new E-TEC 150-HP engine on the classic OUTRAGE 18 boat. The two look very good together, and your performance information indicates the two work very well together.

Nice looking combination. It would be worth it to invest in a stainless steel propeller. Check here on what others have used but the BRP Rebel may be a good choice in the same pitch as the alumimum you have now.

Also note the position of the forward fender; it is in just the right place for a classic hull.

Thanks for the kind remarks and advice on prop selection. I am going to go stainless for next season, and will keep the current prop on board as a spare. I have been considering the Rebel and the Viper. The forward fender is attached to the bow railing using a Taylor Made Rail Fender Hanger, purchased at West Marine, which so far has worked well.

The Viper is a good top speed propeller, the Rebel is a better cruiser.

Appears the motor can be raised at least 1 if not 2 holes.

The consensus from Boston Whaler owners mounting E-TEC outboard engines is to mount them as high as practical.

Spinnaker--I am curious:

What dealer did you use?

What was the approximate cost for your re-power?

Did you or a former owner change the fuel tank?

Thanks.