4 stroke/2 stroke outboards. Difference?

[andy_wilson]

Leaky thinking

I wonder why they are being banned also. The cost of resources of production are greater for a 4 st, they are just more complex. The difference in whole energy cost must be very hard to make up over the life of the item.

It is not beyond the whit of man to come up with a totally degradable 2st oil. The only challenge is therefore better combustion of fuel (a 2st lets a little of the charge of fuel mix chase the exhaust out), or collection of the unburned for re-induction.

If I was designing a 2 st now I would build a small afterburner turbine on the output shaft to deal with the exhaust.

Now thats an idea!!!

 

[Lakesailor]

Re: Leaky thinking

[ QUOTE ]

If I was designing a 2 st now I would build a small afterburner turbine on the output shaft to deal with the exhaust.


[/ QUOTE ] So that would negate it's advantage over the 4 stroke
<span style="color:blue"> "The cost of resources of production are greater for a 4 st, they are just more complex." </span>

 

[Andrew_Fanner]

Re: Leaky thinking

4 stroke is happy to run at tickover for extended periods, 2 stroke wants to be thrashed by comparison, stops it oiling up.

 

[ROSSCO]

just been through the process myself - have a 4 hp 4 stroke yamaha - heavy / underpowered and hard to start px ing for yamah 6 hp twin cylinder 2 stroke which if i believe the sales patter should be smoother running - easier to start and coupled with a sailprop should give me the extra grunt i need

 

[Lakesailor]

[ QUOTE ]
have a 4 hp 4 stroke yamaha - heavy / underpowered and hard to start

[/ QUOTE ] Well strange that. I've changed to the Yam from a 5HP Honda 4 stroke and find it lighter, more powerful and yes it takes 3 pulls to start, but that's the nature of a 4 stroke.

(I take it you're not using it on a 36' Bavaria?)

 

[ROSSCO]

planning to use it as a bow thruster !
- You have a point - will change my profile to reflect my downsizing to a First 211

 

[LadyInBed]

[ QUOTE ]
Starting a 4 stroke requires 2 full engine revs

[/ QUOTE ] Something prods from the back of my memory saying that when starting a 4 stroke you crank it gently till you feel the compression stroke, then crank like buggery!

Yes, that's it, when the Morris 1000 battery was flat and had to resort to the cranking handle, that's the way it was done. /forums/images/graemlins/laugh.gif

 

[ex-Gladys]

Not completely true, since if you crank VERY slowly you won't induct much of a combustion charge from the carb.