# 4-cycle small engines made for mixed fuel ??



## Joel_BC (Nov 10, 2009)

Does anyone have an opinion, based on experience or observation, about the 4-cycle small engines that some companies are making that use _mixed gas_? Several companies (e.g., Stihl, Shindaiwa, and others) are making compact, lightweight engines that use the kind of fuel you'd use in your chainsaw, but the engine is 4-cycle and has a cam, pushrods, stem valves, etc.

Do these engines hold up well and give good service, as compared with comparable 2-cycle engines?


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## foxtrapper (Dec 23, 2003)

Mixed gas, as in mixing oil with the gas? I don't know of any 4-cycle engine that calls for that. 

As for your second question regarding durability, the small 4-cycle engines seem to be holding up just fine. Heavier, but that's about it.


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## Ray (Dec 5, 2002)

I don't know of a four stroke that has oil mixed in the gas, myself, I haven't herd of it, and I've worked on many, it would seem a total waste and unnecessary to me. 
A four stroke engine has an engine oil reservoir just like a car engine. this oils the parts as the engine runs, and it fires every other stroke. Each stroke has 2 cycles. 

On the other hand a cheap 2 stroke for lawn mower or weed eater, etc. has no oiler side and the oil is mixed with the gas. this will allow the engine to wear out quicker, but has much more power near twice as much because it fires every stroke. They use reeds and ports instead of valves. 

However there are quite expensive 2 stroke engines that have oil reservoirs and valves like a 4 stroke but you won't see them unless you work on heavy equipment. Caterpillar, Detroit, Some are also on huge ships and are of giant proportions, these huge 2 strokes with pressurized oil for the inner parts and valves are true power producers, and run for decades.

perhaps these engines are 2 stroke with oilers to give the extra power and oil the inner works like the really good 2 stroke engines used for heavy work. best wishes, ray


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## cfabe (Feb 27, 2005)

Sure enough they are making mixture-lubricated 4-stroke engines:

http://www.stihl.com/isapi/default....producttechnics/stihlengines/4mix/default.htm


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## Joel_BC (Nov 10, 2009)

cfabe said:


> Sure enough they are making mixture-lubricated 4-stroke engines:
> 
> http://www.stihl.com/isapi/default....producttechnics/stihlengines/4mix/default.htm


Hey, guys... cfabe here is correct. Yes, these 4-cycle, small, lightweight engines, designed to be run on mixed gas, are being made. Like I said, Stihl makes them, Shindaiwa does, etc. Apparently they've been available for years.

The real question in my mind is: what are the advantages and/or disadvantages of buying a machine with this sort of engine? Does this type of engine start better, run better, work harder, last longer - _or not_? Maybe it's a nifty idea that works out well in practice, maybe it's not.


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## Wis Bang 2 (Jan 12, 2010)

Reading that link, it blends 2 and 4 stroke technology using mixed oil/gas to lube the internals yet it meets emisions that the 2 strokes can't meet...must have been designed to burn the oil more efficiently than the old two stroke technology which relies on high RPMs to make power [and noise]...interesting.


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## Joel_BC (Nov 10, 2009)

Wis Bang 2 said:


> Reading that link, it blends 2 and 4 stroke technology using mixed oil/gas to lube the internals yet it meets emisions that the 2 strokes can't meet...must have been designed to burn the oil more efficiently than the old two stroke technology which relies on high RPMs to make power [and noise]...interesting.


Yeah, but that's the theory. I want to find out something about how it works out 'in practice'.


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## Ray (Dec 5, 2002)

a 2 stroke has more power than a conventional 4 stroke. It fires every stroke, a 4 stroke fires every other stroke. 
The 4 mix they are talking about is not a conventional 4 stroke. they don't have an oil reservoir, oil pump to oil the inner works, they use the oil mix gas to lube the engine, these will not last nearly as long as a standard 4 stroke, tho may run faster. They can't have more power than a 2 stroke that fires every stroke while the 4 mix only fires every other, but I do see the engine being smaller than standard 4 stroke, what they are trying to achieve here is lower the emissions that a standard 2 stroke put out, not increase power, but keep the machine very small and lightweight at the same time. best wishes, ray


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## foxtrapper (Dec 23, 2003)

Interesting, but for the life of me I can't see what the Stihl 4-power engine gains. It's still a 4-cycle engine, so the power curve is standard 4-cycle. Still has all the valves and such, so weight and complexity is not changed. All you gain is much worse lubrication, which should greatly shorten the engine life.


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## Cabin Fever (May 10, 2002)

Don't be surprised if you see the two-stoke engine slowly phased out of all power power equipment (due to air pollution laws) and gone forever. I'm really tempted to buy up a couple standard two-stoke chainsaws....Jonsereds, of course....while I can still get 'em with a standard two-stroke engine. I'll store those chainsaws until my current ones die.


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## HermitJohn (May 10, 2002)

foxtrapper said:


> Interesting, but for the life of me I can't see what the Stihl 4-power engine gains. It's still a 4-cycle engine, so the power curve is standard 4-cycle. Still has all the valves and such, so weight and complexity is not changed. All you gain is much worse lubrication, which should greatly shorten the engine life.


Its all about EPA emissions. EPA hates diesels and 2 cycle engines and is exerting great pressure for a workable alternative. 4 cycle engines have lower emissions, but having an oil sump on something like a chainsaw just isnt economically workable so they came up with this workaround. You get slightly heavier saw, more complexity, maybe lower lifespan (I dont know), but you do get slightly lower emissions.

The law of diminishing returns does start to come in effect. On cars, PCV system was first pollution control and was incredibly cost effective for amount of pollution reduction, and meant less sludge buildup in engine to boot. WIN-WIN for everybody and I really cringe when I read about some clueless person that wants to remove PCV system from his car cause he hates pollution controls. He is shooting himself in foot with lower engine life. However its been sometime since any additional pollution controls truly cut total pollution output significantly and systems have grown incredibly complex and expensive. At this point the way to reduce pollution further is to discourage cars as way to travel, and trucks as way to move goods long distances, not to go after that last infinitesimal amount of pollution generated by an individual engine at huge cost to benefit ratio. Too many humans driving too many cars too many miles is the problem at this point, not amount pollution produced by an individual vehicle. 

Possibly the same with small engines, discourage use of small engines rather than trying to engineer them into some incredibly complex and expensive clean machines. Its incredible all the waste in people growing and watering huge non-productive lawns that then have to be mowed and otherwise cared for. Maybe banning lawns over certain size would be most effective?? I dont like restricting my personal freedoms, but people should have thought about that before they decided to be fruitful and multiply to an extreme degree, then when corporate America wasnt getting fast enough increase in number of new consumers, they opened the borders. Finite planet with finite resources so something has to give.


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## HermitJohn (May 10, 2002)

Cabin Fever said:


> Don't be surprised if you see the two-stoke engine slowly phased out of all power power equipment (due to air pollution laws) and gone forever. I'm really tempted to buy up a couple standard two-stoke chainsaws....Jonsereds, of course....while I can still get 'em with a standard two-stroke engine. I'll store those chainsaws until my current ones die.



Then what happens when parts are no longer available for your hoarded treasure? Or we are forced to burn 100% alcohol and your stored saws arent capable of that?


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## Cabin Fever (May 10, 2002)

I sell them on Ebay as rare antiques.


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## HermitJohn (May 10, 2002)

I wonder exactly how much an unused historic engine would bring. I have an elderly friend who has a brand new still in original box, small outboard motor from the 1950s up in his attic. Truly you arent going to find something like that very often, however what would its value be other than as a museum relic? If anybody actually used it, its value would be diminished greatly I would think. But who really wants to look at an outboard motor??


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## Joel_BC (Nov 10, 2009)

HermitJohn said:


> I wonder exactly how much an unused historic engine would bring. I have an elderly friend who has a brand new still in original box, small outboard motor from the 1950s up in his attic. Truly you arent going to find something like that very often, however what would its value be other than as a museum relic? If anybody actually used it, its value would be diminished greatly I would think. But who really wants to look at an outboard motor??


Admittedly, we're veering off-otopic here. But it's an interesting question, Hermit John.

I'm in a country that is divided into "provinces" in the same way the U.S. is composed of "states". I'm in British Columbia, western-most province in Canada. The provincial museum, in our provincial capital city (Victoria), has a room displaying the general lifestyle and technology of various periods, such as the 1880s, 1920, 1940, 1955, 1970, etc (I'm writing this from memory, so the dates may not be quite right - but this is the idea). In these displays, they include various hand-operated and powered technological features of the eras (e.g., before and after home refrigerators, etc).

So that's an example of where there might be an interest in acquiring and "collecting" something like an unused outboard motor from 1950. (Unusual and pretty specialized need.)


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## Cabin Fever (May 10, 2002)

HermitJohn said:


> I wonder exactly how much an unused historic engine would bring....But who really wants to look at an outboard motor??


SOLD $1053 on Ebay









SOLD $750 on Ebay









ASKING $6500 on Ebay


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## Cabin Fever (May 10, 2002)

HermitJohn said:


> Then what happens when parts are no longer available for your hoarded treasure?....


No problem-o Search Ebay for chainsaw parts, Model T Ford parts, mower parts, antique tractor parts, etc....you find 1000's of used parts for sale.


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## phrogpharmer (Apr 25, 2005)

I got a Stihl 4mix string trimmer about a year ago and have used it quite a bit. Had a couple problems with it running rough at first. The dealer checked it out and recommended using the more expensive Stihl oil and I haven't had any problems since.


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