[blinx78]

Hello,

I'm new to the boating world. I'm renting out my buddy's lakehouse and he has a little aluminum boat with an Evinrude 6hp motor. The model # is a 6202. I don't know much about boat motors... but i know if it's a 2 stroke, it needs pre-mix and if its a 4 stroke, it doesn't. I don't want to run the wrong fuel in it...could someone help this clueless city slicker out? THANKS!

-Kylie

[JamieScott]

Hello Kylie

I'm also new to the boating world so you're not on your own! iboats forum it the place to get help though so well done for finding it.

To see if it's a two stroke engine (which I imagine it is) take off the engine cover. This should be fairly easy to do. (On my outboard on the back under the top of the engine is a leaver that you slide across and then you can lift up the cover). Once it's off then have a look to see how many spark plugs you can see. The plugs have the electrical leads running from the top of them and are sticking out of the engine. If it only has two plugs then it's a 2 stroke engine and as you say you will need to premix outboard 2 stroke oil into the fuel. If this is the case you will need to make sure that you mix the correct amount of 2 stoke oil into the petrol. My outboard which is a Johnson 6hp takes a mix of 50:1 (fifty parts of petrol to one part of 2 stroke oil.)

Someone more experienced than me will be able to tell you the exact mixture of 2 stroke oil for your motor so you don't make any mistakes.

Have fun on the water!!

Jamie

[Vic.S]

If it only had two plugs then it's a 2 stroke engine

?????????????????? the number of plugs is not an indication of whether it is a two stoke or not. Until fairly recently the vast majority of outboard engines where in fact 2 strokes irrespective of whether they had 1, 2, 3, 4, 6 or even 8 cylinders and plugs to match!


However Evinrude 6hp model #6202 is in fact a two cylinder two stroke made in 1972.

The correct fuel mix is 50 parts gas to 1 part oil. The oil should be an 2 cycle outboard engine oil to TC-W3 specification (the current spec for 2stroke outboard oils). The gas is what I think you call "regular" unleaded. The bog standard low octane stuff in other words although no harm will come from using a higher octane.

[JamieScott]

As I said I'm new to the boating world... I thought that's how you could tell. At least I was right even though I was wrong - if that makes any sense??!

Jamie

[Vic.S]

The difference between a two stoke and a four stroke:

A two stroke fires every revolution of the crankshaft (on every cylinder). It is called two stroke because that's one upward movement of the piston and one downward movement. The description HEREis quite good. You will notice that the crankcase is involved in the admittance of the fuel/air mix and so cannot act as an oil reservoir. That is why the engine is lubricated by oil mixed in the fuel.

It's a bit difficult to understand that a 2 stroke actually works but of coure it does!

Click the link on the above webpage and you will get a rather brief explanation of a 4 stroke cycle. Called four stroke because it fires once very 2 revolutions of the crankshaft ie 4 strokes, two upward and two downward movements of the piston. The admittance of the fuel air mixture is controlled by a valve and the expulsion of the exhaust gases by another. On the first (downward) stroke the inlet valve opens and the fuel air mixture is drawn into the cylinder. The valve closes and the mixture is compressed by the next (upward) stroke. As the piston approaches the top of its stroke the mixture is ignited and the piston is driven down again by the force of the combustion. Finally as the piston rises again on the fourth stroke of the sequence the exhaust valve opens and the gases are expelled.

You will notice that the crank case in a four stroke engine is not involved in the transfer of the fuel air mixture so it can function as a reservoir (or sump) for lubricating oil. The oil is pumped to all the bearings etc by means of an internal pump.

Physically then the four stroke engine is distinguished by the oil sump the valves and a cam shaft and other components necessary to drive the cam shaft and operate the valves.

Both two and four stroke engines can have any number of cylinders and hence spark plugs from one upwards.

[blinx78]

Wow, thanks for all the great help... and such quick responses! I know a little bit about car engines, so everything you said explaining how the 2 stroke works make sense... I'm just not much as far as identifying that sort of thing just by looking at it.

There's some 2 stroke oil in the garage for the weed whacker, the bottle's almost full so that should work for the boat too! It said "up to TC-W3 specs" on the bottle...I remember that much, so I should be all set, eh? :-) Thanks again! Much appreciated! Now as soon as it stops raining... I can go for a ride!

[tx1961whaler]

DO NOT use the weed-whacker 2 cycle oil for your outboard engine unless you are absolutely sure. Use only oil designed for a water cooler outboard. It's very cheap, so if you have any doubts, just go to Wal-Mart and buy some.