Is it ok to run a 4 stroke on 2 stroke mix?

[haddles]

I have a 2 stroke main motor and a 4 stroke auxillary (both Yamaha). The 4 stroke has a 1 litre internal tank which isn't good for much and the main motor is so reliable i'd imagine the fuel would go stale (even if I carried a spare fuel can) before I had to use it. Can I just hook up the fuel line from the 2 stroke to the auxillary and run it on 50:1 without any ill effects? The little 4 stroke would be full throttle the whole time.

 

[JB]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

The 4 stroke will run on premix, haddles, but I wouldn't promise no ill effects. I can promise smoke and stink.<br /><br />I think I would consider other options, like hooking the oil injection back up on the big 2 stroke so that what's in the fuel tank is oil-free petrol.<br /><br />Good luck.

 

[haddles]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

No premix on the 2 stroke. It's an enduro model which is sort of an agricultural, heavy duty model or so the advertising says. I've actually tried running the 4 stroke on the 50:1 main tank as an experiment and it surprisingly didn't seem to blow any noticeable smoke at all. Dunno where the oil went! but it ran fine. Didn't know whether I was hurting it in the longer term though.

 

[surlyjoe]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

for years I have run 50:1 mixed for my bikes in my B&S 4 cycle lawn mower engine. it still starts first pull, alltho last time I changed the plug it was gunked up pretty nasty. lawnmowers are only a couple hundred bucks tho...

 

[Texasmark]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

The fact that you run the 4 stroke at full throttle probably would offset most problems.<br /><br />Will probably have to clean the plug more often than regular and the exhaust ports could get gummed up. But per all the instructions on here, if you decarb once per season that problem should be a no brainer. Need to keep clean oil in the crankcase of the 4 stroker anyway (due to condensation....not related to fuel), so when you change the oil, clean the plug and decarb and you should be fit.<br /><br />I mean like the 2 stroke that uses the mix has a piston and cylinder and sparkplug and all just like the 4 stroke. Only difference is the power stroke length and number of revs per hit. It runs just fine on it, so why shouldn't the 4?<br /><br />I think it'll work just fine.<br /><br />Mark

 

[Cricket Too]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

If you don't premix for the 2 stroke then what you have in your main tank is straight gas, correct? So when you switch the line to your 4 stroke you are running straight gas through, the way you should. That's why you have no smoke or problems. If you don't premix the the main tank yourself, it's not premixed, the gas and oil mix to 50:1 occurs in the engine. Your main tank is straight gasoline.

 

[haddles]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

I meant no oil injection sorry. The main motor runs on premix at 50:1 which is what is in the tank.

 

[cobra 3.0]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

I have run it for years on various four stroke engines. There has been no ill effect on the engines. It's just extra lube for the pistons. I can't see how this could this be harmful. The dirty plug concerns and a little more stink is the only noticable difference. So,I change my plugs a little more often, but plugs are cheap.

 

[imported_Curmudgeon]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

The dirty plug concerns and a little more stink is the only noticable difference.<br /><br />The stink and dirty plugs probably come from incomplete combustion of the oil. What you see on the plugs is likely building up on valves and heads, also. If "extra lube for the pistons" was a good thing, seems manufacturers would recommend it for all their 4 strokes.

 

[cobra 3.0]

Re: Is it ok to run a 4 stroke on 2 stroke mix?

Everything is relative. There isn't enough oil in there to cause any build up of anything. I am not talking about clouds of smoke (it's hardly detectable) or spark plug changes everytime you go out (I truly can't even really say if I change the plugs more often. I change them every year whether my plugs look good or not just to be safe.) Two strokes run all day with this mix AND because, of the nature of 2 strokes, have unburned fuel and oil running straight out of the exhaust all the time whereas four strokes don't.