Is A Stihl 4-Mix Engine A 2-Stroke Or A 4-Stroke? (DAY 1)

DAY 1 of ⭐30 DAYS OF QUESTIONS⭐ Is a Stihl 4-mix engine a 2-stroke or a 4-stroke? Steve has the answer!
Click below 👇👇👇 for the links to the other questions...

I go on a bit of a rant to clarify whether a Stihl 4-mix engine is a 2-stroke or a 4-stroke. There is a lot of confusion over these Stihl 4-mix engines. People actually think they are 2-stroke engines as they take 2-stroke gas because there is no engine oil in the sump. I break it down for you and explain how the Stihl 4-mix engine works.

And straight from the Stihl website ➜ The 4-Mix Engine: The award-winning STIHL four-stroke engine that runs on a petrol-oil mix. The STIHL 4-MIX engine thus combines the advantages of a 2-stroke and a 4-stroke. As well has having plenty of lugging power and perceptibly higher torque, the 4-MIX engine is also convincing in terms of lower emissions, low maintenance and a pleasant sound.

⭐30 DAYS OF QUESTIONS⭐ - (Links will be updated as the videos are put out)

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[StevesSmallEngineSaloon]

Click below 👇👇👇 for the links to the other questions...
⭐30 DAYS OF QUESTIONS⭐ - (Links will be updated as the videos are put out)

[waynerowlinson]

I was given a 4-mix engine weed whacker a few years ago by a buddy who simply didn't get the concept of mixing fuel for his 4 stroke engine. Fortunately for me he bought it thinking he didn't have to mix fuel anymore. I did get it before he put straight fuel in it though. He's since moved on to, sigh, a cordless trimmer.
Next to bacon, the smell of burnt mixed fuel is my favourite smell on the planet.

[randy]

I’m a Stihl dealer and I dread this question every spring. I even have two cut-away engines, FS90R and a FS85R. We use these to try to explain, and the key word is “try”. It’s almost spring, guess I’d better go and find my cut-away engines.

[TheeHypnotoad]

The frustration is real Steve! I used to work in lawncare and got a 4 mix trimmer. My boss used crapsman 4 srokes (side rant, those are the biggest pos trimmers out there people, avoid at all cost!) and I was explaining that the 4 mix was a 4 stroke but took mixed fuel so you could turn em whatever direction and not care about an oil sump. He said that same thing you've heard, "if it takes mixed fuel, thats a two stroke!" I tried explaining the valves, how a 4 stroke works in operation, that there's two stroke marine diesels with an oil sump, just could not get it through to the guy! He decided that I just "didn't know the difference between 2 stoke and 2 cycle"... the stuff people will make up to save face is amazing, ha! Good vid, keep it up Steve!

[capnpugwash]

I guess there’s a good reason for it or presumably Stihl wouldn’t make them, but a straight 2 stroke from experience with bikes firing every time the piston hits tdc generates more power in a small engine than a 4 stroke where it fires every other time it reaches tdc. I dread to think what the exhaust valve looks like.

[omniscientgrunk]

I liked your "tone " Steve. I always admire the truth told. Ignorance is annoying, willful ignorance is appalling. I think the 25 year man was just in a bubble...perhaps. John from Michigan

[SmallEngineDIY]

Amen. I'm glad someone else can explain the engines. I have successfully explained to a few customers, but many just don't get it, or refuse to understand.

[jameswyeth]

Hi Steve, also lots of people use the standard mineral 2stroke oil in the four mix units when you should use the ultra oil to protect the valves.

[richnorman]

Great “rant” Steve… well deserved. Stihl Tec needs to pay attention in school. The 4 Mix is quite a unique engine….valves and mix. Pretty ingenious design actually!
Great answer BTW!!

[marklubecke]

Valves, intake, compression,
power, exhaust (4 stroke engine).
Thanks for all you do.

[micahromig]

I just got my Gold cert in VA Beach. From everything ive learned in the short year and a half ive been doing handhelds, you are 100% correct!

[pir]

I'd assume the intake tract is connected to the crank case as in a 2T to lube the crank big and small ends, the fuel/oil mix would run around the valve gear too before it goes into the cylinder via the intake valve.
I can say that some 4T engines have dry sumps with with an oil tank, all thing possible, but to add the weight of the valve gear etc and still have to premix, i'd plum for the simple mechanics of a 2T every time.

I own a few 2T garden implements, a 2T motocross bike(1989 RM250) and a 4T triumph spitfire, the only other 4r 4T i'd get would be an enduro bike or a farm quad....2T racing quads kick ass.
2T is super easy to tune for power too from case matching, costs a new gasket and some elbow grease.

[wg]

And you need to adjust the valves on those things from time to time . If they get hard to pull over and kick back when cranking it's time for a valve adjust and Stihl offers a special little feeler gauge to do that job . I know, I have two FS 130 and they are very powerful . They have been used and abused cause I got them from a lawn maintenance company .

[vipahman]

That was a good rant. 4-mix = 4-stroke running on gas-oil mix.

[markinator]

I just RTFM and use what it tells me too...dont care what/how...just that it starts when I pull the handle...your colorful explanation is perfect, don't change a thing!!

[stevenakn]

I've recently switched to stihl and im learning there ins ands outs. Like cleaning carbon and adjusting valves. I have the hedge trimmers as well and one falls on its face when you hit the gas but i don't see a valve cover. Already replaced the carb with no change. Any advice? Thank you
I'll add it's about 2 years old and been run hard daily 🔧

[bobblenuts]

Wow Steve, I think that question struck a nerve...LOL. I don't have one of these engines but saw or read somewhere that using the Stihl brand formulated fuel mix in these engines is somewhat essential for survival. Maybe it was your video, I don't recall.
Thanks for your question series, hope the next one is easier on ya...Cheers 🍺

[jamiecrisp]

Great video Steve the way a 4 mix engine lubricates itself is the intake where the carburetor is mounted the port is connected to the crankcase under the valve cover only half of the fuel is actually burned in the combustion chamber the rest goes through the valve compartment then down the push rod wells to the tappets which then lubricates the cam gear and then finally into the crankcase to the wrist bearing, crankshaft and bearings and then out the crankcase breather tube back to the intake to recycle it this only works if all the engine seals are in good shape one pinhole in any seal will cause the engine to run lean or not run at all the reason 4 mix engines have no sump is to save on weight and keep the equipment compact.

[TimsWorkshopTJY]

How you all doing up North? It's been a long cold wet winter so far down here by the puget sound. So ready for spring. I did fire up my chainsaw to cut up some firewood. Needs maintenance this year for sure and fresh gas

[MWestern-mg]

That is confusing as hell. The Stihl is a 4 stroke engine that uses 2 stroke premix so they decided to call it 4 mix (meaning 4strokewithoilinthegas). Detroit "Screamin" Jimmies were 2 stoke engines that had exhaust valves but uses diesel for fuel and has an oil sump for lubrication.