air cooled or water cooled

[blue fin]

I have recently aquired a 1974 eska wizard 7hp tg. It took some doing but i brought this motor back from the dead. can anyone please tell me if this outboard is air cooled or water cooled. and also if you could tell me what the tg means after the hp . I cannot figure out how to remove the lower unit on this motor. Any and all help is greatly appreciated. thanks in advance!!!!8)

 

[steelespike]

Re: air cooled or water cooled

Wizards were sold by Western Auto.My Guess is TG is just a couple of letters they thought looked good.
Your motor is air cooled with a pump to cool the exhaust leg.Water should mist out of the relief holes in the leg.
You should be working with a manual.My manual covers many brands under 30 hp.
I believe the lower unit has a nut under a cover on the leading edge and another in the exhaust outlet.

 

[itstippy]

Re: air cooled or water cooled

A common misconception is that "air cooled" outboards don't need to pump water. They do. The powerhead has external air cooling fins on it instead of internal water passages, so it is indeed "air cooled". However, it also NEEDS to have water pump up and cool the exhaust housing. This reduces heat throughout the powerhead. Without this additional cooling the "air cooled" powerhead will quickly overheat and seize. Quickly meaning within five or ten minutes.
I believe there is a critical horsepower point where a 2 cycle engine requires additional cooling. I've run truely "air cooled" brush trimmers and chain saws for long periods without overheating. The cylinders were about the size of a nickel or a quarter, though, and the horsepower wasn't that great. Once you start putting out 5-7HP with constant load, like an outboard has, it seems additional cooling is a must.

 

[steelespike]

Re: air cooled or water cooled

Your right itstippy if you are going to run the exhaust under water you need to cool it.
However the Briggs and Stratton 5 hp.outboard uses a simple muffler and no water cooling.
I'll bet that muffler is a scorcher but apparently the motors work ok.I understand they are noisy and vibrate pretty good but as a cheap portable motor I guess they serve.

 

[QC]

Re: air cooled or water cooled

I have only run my B & S twice now. I kinda ended up with this thing as opposed to wanting it. Anyway steelespike is correct, noisy, vibrates, but indeed makes at least 5 hp and did not appear to have any overheat issues with 80+ degree ambient and extended full throttle use . . .

 

[blue fin]

Re: air cooled or water cooled

Thanks guys all of your help is greatly appreciated thanks for your time and input!!!! very -very helpful

 

[itstippy]

Re: air cooled or water cooled

I think the B&S outboards are 4 stroke "lawnmower" type engines? They'll run indefinately totally air-cooled. My "horsepower limit" theory is for light 2-cycles. It seems to get the light weight & horsepower & high RPM combination that is desireable in a chainsaw or brush trimmer or outboard you can only go so far up the horsepower chain before heat becomes an issue. I guess it's really a cylinder displacement/external cooling surface/overall engine mass ratio that dictates the HP limit.
There have been 2 cycle cars that worked (Russian Trabant). I'll bet since they're on wheels they are not designed with the impressive HP/weight ratios of 2 cycle weedeaters, chain saws, and outboards.

 

[pinedaddy]

Re: air cooled or water cooled

In the 1970s kawasaki and yamaha had some very powerful air cooled 2 stroke motorcycles (suzuki had some less impressive models) I've owned several from all 3 manufacturers, never had an overheat problem on any. I've used these engines on go carts and atvs also. awesome engines. But I do know that big 2 strokes have a tuned exhaust to scavenge, or pull the exhaust out of the cumbustion chamber, and taking a lot of heat with it, which might not be possible if it has to push its way out through water.

 

[steelespike]

Re: air cooled or water cooled

The cooling problems with the B&S outboard is when you attempt to troll.
I don't think there is any limitation for the size of an air cooled engine whether 2 stroke or 4 stroke.
Franklin autos built air cooled motors up to 12 cylinders.Their engine devision also built air cooled airplane engines. Their 6 cylinder car engine developed 100 hp in about 1930.
Then there are many other brands of air cooled radial
air plane engines I believe up to 18 cylinders that were very succesful.air cooled motorcycle engines are basically static cooled just by the motion through the air.Both 2 stroke and 4 stroke.Imagine what fan forced cooling could do.
I believe you can air cool any engine if properly equiped with fan forced cooling system.
Franklin redesigned their system in the late 20s to make it cool better with something like 30% less load on the engine.
I do feel that an air cooled engine may require more frequent rebuilds.Especially the 4 strokes.

 

[Paul Moir]

Re: air cooled or water cooled

Side note: TG - Twist Grip Throttle.