Capacity and a question about the twins

[Rhojo]

Although the badges are still on the boat I haven't taken the time to try and read them, they are very faded and a little pitted, I suppose I could get this info off them eventually but I need to know the carrying capacity of my boat, anyone know? (edit: the '78 brochure says capacity is 1,590 lbs., '80 brochure says 2,000 lbs.)

Also, I'm new to 2-stroke outboards and I don't know what WOT will be.

I did get the boat in the water last weekend and we cruised at 3,000 rpm at about 22.4 mph on the gps. At 5,000 we were going 30 mph. I didn't go any higher than that. The Twins ran well, never missed a beat and no stalls or anything when docking. My maintenance work seems to have paid off! I saved about $600 off the estimate from my marine mechanic.  :pirat: The knowledge of some of the regular maintenance was/is priceless!

The Admiral :queen:  and I had a great day on the lake!

[fitz73222]

Hey Jon,
Speaking for the outboards, and rigging many 3 cylinder OMC`s years ago. It is critical particulary on those engines not to overprop them. Your powerheads did have the larger crankshaft bearings that were introduced in 85` if memory serves. We used to prop them a little light and rev them up to 5800-6000 rpm. Earlier models didnt have the internal bearing support to push heavy loads. Next time you have her out, push the throttles WOT and see what she tachs. If your above 5600 you should be fine. Obviously someone was doing something right if these are original powerheads. Stick with the best oil you can buy and 89 octane fuel and they will live forever. Most of the failures we saw were connecting rod bearings and broken rod caps. In most of the situations we noticed they were over propped and didnt rev within the recommended factory rpm.

[Rhojo]

Hey Jon,
Speaking for the outboards, and rigging many 3 cylinder OMC`s years ago. It is critical particulary on those engines not to overprop them. Your powerheads did have the larger crankshaft bearings that were introduced in 85` if memory serves. We used to prop them a little light and rev them up to 5800-6000 rpm. Earlier models didnt have the internal bearing support to push heavy loads. Next time you have her out, push the throttles WOT and see what she tachs. If your above 5600 you should be fine. Obviously someone was doing something right if these are original powerheads. Stick with the best oil you can buy and 89 octane fuel and they will live forever. Most of the failures we saw were connecting rod bearings and broken rod caps. In most of the situations we noticed they were over propped and didnt rev within the recommended factory rpm.

Fitz, thanks so much! Great info here. I have been running only 87 octane up till now so I will definately move up to the 89. I have been running the Johnson XD30 2-stroke oil, bottle says it's a semi-synthetic. I've also been reading about the ethanol issues and I really don't know if my fuel lines are rated for it so I have been using the marine Sta-bil everytime I add any gas even if I'm not sure if the gas I'm getting is ethanol. I thought I'd be able to tell at the pump, looking for a label or sign somewhere, but I haven't seen anything that identifies ethanol.

We'll be going out again this weekend so I will defiantely try her at WOT and see what I get.

Thanks again!

Jon

[fitz73222]

Hey Jon,

Chances are, the fuel you are buying contains ethanol. Usually there is some decal or placard that states that the fuel contains 10% or less ethanol somewhere on the pump. Now, down to nuts and bolts. Do you have water separators/fuel filters for each engine? If not, they need to be 10 micron filter media with sightbowls so you can see any water that accumulates and drain as needed. Racor or Moeller makes the kits. Spend the money and buy the stainless steel filter mounts. Cost will be around $190. with the fuel line barbs. Tee off the main line too each engine and install the filter assemblies. Unless the fuel tank has been replaced; it may have the original main fuel line. Once you put on the water separators, the sightbowls will indicate if the fuel lines are degrading and show up as sediment "chunks" or black "ring around the collar" in the sightbowl, then respond accordingly.Sounds like your handy twisting wrenches and that will surely come in handy! The later designed 70`s like you have were true outboard warriors and fastest way to end their long lives is injesting water from crap fuel. Keep up with Stabil or Startron and buy gas from a volume dealer that gets deliveries often so you are always dealing with fresh fuel and a little more shelf life.