2 stroke fuel in a 4 stroke engine

  • Thread starter Thread starter bbg
  • Start date Start date

bbg

Well-Known Member
Joined
2 May 2005
Messages
6,780
Visit site
I just disposed of my old, unreliable 2 stroke for a fancy new Honda 2.2 four stroke. What joy to hear it come to life on the first or second pull, and actually expect it to keep running until I get back to the dock!
But I have maybe 5 litres of premix left (75:1). Is it unwise to put this into the new engine, even in dilute quantities? I was thinking of putting 1 litre into a 5 litre can (together with four litres of straight unleaded) which should make the mix 375:1.

This seems to me to be so low as to be nelgigible. Am I running any real risk by doing this?

Thanks
 
I just disposed of my old, unreliable 2 stroke for a fancy new Honda 2.2 four stroke. What joy to hear it come to life on the first or second pull, and actually expect it to keep running until I get back to the dock!
But I have maybe 5 litres of premix left (75:1). Is it unwise to put this into the new engine, even in dilute quantities? I was thinking of putting 1 litre into a 5 litre can (together with four litres of straight unleaded) which should make the mix 375:1.

This seems to me to be so low as to be nelgigible. Am I running any real risk by doing this?

Thanks

think of it as upper cylinder lube, it might foul the plug it will run with smoke.
have you a lawnmower or car you might use it in
 
I just realised - I already know the answer. It would be stupid to even risk doing it with a brand new engine. It is just a bit of a hassle to get rid of the used fuel, but it is only 4 or 5 litres so it isn't like I'll be throwing away hundreds of €.
 
It does not do any arm at all. Why would it? On the contrary, it would help the new engine to run-in more smoothly. Bear in mind that small four stroke engines do not have an oil pump to lubricate perfectly all parts. Lubrication happens by "splash", which is less than ideal. This way the tappets hardly get any oil.

The only side effect would be a bit less power and more smoke. In that case dilute to mitigate.
 
I would dilute it a bit, and probably wait until you're willing to use a few revs, lest you foul the plug. But if it was mixed with half decent 2T oil, it will be fine. OTOH, if the engine goes back under warranty and they find oil in the tank, what then?
Maybe best to find someone with a lawnmower or genny that is out of warranty if you are going to worry. In the days before catalysts, I'd have put it in my car, now I'd probably put it in my motorbike or give it away.
 
It'll do no harm but it might be unwise to use it in a engine still under warranty.

It'll lubricate the upper cylinder and the valve stems. Not the parts like crank shaft, camshaft, tappets, rockers etc that are catered for by the 4 stroke's lubrication system.

Use as much of it as possible in the lawn mower etc and in a petrol car if SWMBO has one
 
Last edited:
Top