O/T 2 CYCLE AIR COOL mtrs.

There are very few parts, but it's all here:

Don't know of any part in a 2 smoke that doesn't get some portion of the mix to them. That is why the shaft seals on them are so important. Lube wise there is the crank bearings, rod bearing and wrist pin. They are all usually roller bearings and all are lubed by the premix. Rings get lubed the same way as any other engine. What's left?

I can't think of an internal part that DOESN'T get exposed to the mix, so I don't understand your question.

Uhhh. yeah. Its called "oil." The additive package for 2-cycle oil is more concerned with using additives that reduce smoking and carbon deposits.

Chainsaws have a separate place where you put in lubricating oil.

thanks John, Steve, No-name, that answers the question. =3D=3D=3D=3D

is this for the chain?

=3D=3D=3D=3D=3D=3D Thought I would toss this in for those who are concerned, a mechanic told me one

time that these air-cooled 2-cycle engines operate better when they are run at high R P M S occasionally during each use. Helps keep the ports open. Makes sense.

mho v=83e

Chain oil.

Lets reverse the question. There's a 4 stroke string trimmer thats made by stihl- it uses premix. How the heck they lube the cam/rockers/ whatever they have for valve operation? The stihl fs110... Pat

Good question, why don't you look into it and report back.

View this thread:

Interesting link on the 4-Mix, thanks for posting it. Two questions come to mind.

1. I wonder if carbon build-up will be an issue on a valved motor that burns oil as a part of the combustion cycle.
2. Are seals a long term potential problem since the crankcase and and overhead areas have to be well sealed to permit alternating pressure and vacuum.

For the CHAIN, not for the engine.

My reaction is, "That's the STUPIDEST thing I've ever seen!"

The WHOLE POINT of switching to 4-strokes in these applications is to reduce emissions. Sure, a 4-stroke burning premix is marginally cleaner than a 2-stroke, but its still burning premix and emitting tons of HC and carbon from the oil. It defeats 90% of the purpose.

Yeah, I'm not sure which emissions standards were omitted in getting this engine certified for CARB but they must have dropped hydrocarbon. Also, to my uneducated eye it doesn't seem like an inherently efficient design since the fuel/oil mix has to be pumped around and through so many orofices for proper lubrication. I wonder how the fuel consumption and power output is compared to a conventional 4 stroke engine of comparable size.

I suspect that carboned-up valves and leaky seals will be long-term problems with this design.

Still it is an improvement over the outdated 2 cycle engine.

I would think the advantage of a 4-stroke engine is that the power curve is a little better... you have a wider range of engine speeds at which you can get good power.

--scott

I could see it having comparable power in spite of all the monkey business- its the emissions that seem silly.

In what way?!? Its more complicated, heavier, and still emits just as much crud. The only real problem with the 2-stroke is emissions- they're very light and more powerful per pound of weight than a 4-stroke in those small sizes.

If it emits less emissions including partially burnt fuel than a 2 stroke then it is an improvement. How much of an improvement I can't determine. Perhaps you've found comparative data, because I haven't.

The increased number of parts isn't an issue per se because the basic design of the 4 stroke motor is well established. Using the piston to pump of fuel/air mixture up, down and through numerous orifices for lubrication makes me think a fair amount of energy is used in the process however.

Two strokes put out a good deal of power for their physical size, but they use a good amount of fuel in the process and are not very efficient at converting fuel to power - some fuel goes partly or completely uncombusted. They are a cheap to manufacture compact power source that had until recently could claim to be the only design that could be run in any position.

An honest comparison of comparably sized 2 stroke, 4 mix and 4 stroke motors is what is needed. All I found were glittering and general comments in the online Pop Science and Pop Mechanics.

It does seem silly to pump fuel/oil in and out of the crankcase, but isn't this almost like a PCV system on a normal 4-cycle? The PCV system removes vapors of unburnt fuel that slips past the rings, and other bad stuff. Plus using valves instead of reeds and ports allows you to control emmisions better. I think this is where it's more efficient than a 2-cycle..

If its something I've got to carry for a couple of hours like a weed-whacker/brush trimmer, then WEIGHT is a huge deal. Its really hard for a 4-stroke to win on weight. And also, I don't know about other people but I'm not willing to spend much maintenance effort on a little convenience like a weed-whacker. My mower is a necessity so I'll change the oil and filters and take care of it like I do my car. My weed-whacker and leaf blower are luxuries- and if I've got to dick around with it, it goes out the door in a hurry. Two-strokes are just about zero-maintenance (at least the GOOD ones- I've had some that were terrible... note the PAST TENSE there! :-) I don't think I've even changed the spark plug in my Echo weed-whacker in about 4 years. Just add fuel mix and go.

I agree 100%. That's nowhere to be found- its just my gut feeling that the "4-mix" is the worst of both worlds. One other benefit it might have is that Stihl sells a lot to big lawn-care companies, probably more than they do t to individuals. The 4-mix would fit nicely in with a buch of

2-strokes in that it doesn't require a different fuel than the other weed-whackers. Switching to 4-strokes from 2-strokes might mean that a lot of employees mistakenly put mix fuel in the 4-strokes- not fatal probably, but it would sure cause starting and plug-fouling problems. But the reverse- putting straight gasoline in the 2-strokes- WOULD be fatal to them.

Good points.