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Question about 4-cycle trimmer

#1

cpurvis

cpurvis

How is the lower end of the engine lubricated?

I don't understand this thing at all--a 4 cycle engine that takes mixed gas?


#2

cpurvis

cpurvis

Never mind.

I found something on the Stihl website that explains the 4-mix engine.


#3

H

helomech

4 stroke and 2 stroke have nothing to do with the type of gas, or if there is a oil gas mix. It just means the amount of strokes in the engine per cycle. A 4 stroke can run on oil mix, and a 2 stroke can run on straight gas. Just depends on how they are designed.

Lots of old 2 stroke diesel engines out there that don't have oil added to the fuel.


#4

I

ILENGINE

helomech said:
4 stroke and 2 stroke have nothing to do with the type of gas, or if there is a oil gas mix. It just means the amount of strokes in the engine per cycle. A 4 stroke can run on oil mix, and a 2 stroke can run on straight gas. Just depends on how they are designed.

Lots of old 2 stroke diesel engines out there that don't have oil added to the fuel.
Click to expand...

Locomotives are a good example of 2 cycle diesel engines.


#5

H

helomech

ILENGINE said:
Locomotives are a good example of 2 cycle diesel engines.
Click to expand...

Submarines also


#6

cpurvis

cpurvis

I'm familiar with 2-stroke diesels. The old Detroits have exhaust valves but no intakes and crankcases full of oil.

It was the 'no crankcase oil' part of the Stihl that puzzled me. I knew some 2-strokes have crankcases with oil but I thought ALL 4-strokes did. Until yesterday.


#7

zman111666

zman111666

So far, most of the 4 stroke trimmers I have run across do have oil in the sump, It's only like 3 ounces, and they have a fill plug. This is true for Honda, Craftsman, Troy-Bilt, Ryobi, and huskys. The pics below show locations of oil fill/drain.

4stroketrimmer1.jpg4stroketrimmer2.jpg4stroketrimmer3.jpg4stroketrimmer4.jpg4stroketrimmer5.jpg

On the other hand, I have also seen the ones that take mix, but have the full 4-stroke setup. (valves and camshaft). runs like a 4 cycle, lubricated like a 2 cycle.


#8

B

blueberrymuzik

zman111666 said:
So far, most of the 4 stroke trimmers I have run across do have oil in the sump, It's only like 3 ounces, and they have a fill plug. This is true for Honda, Craftsman, Troy-Bilt, Ryobi, and huskys. The pics below show locations of oil fill/drain.

View attachment 34305View attachment 34306View attachment 34307View attachment 34308View attachment 34309

On the other hand, I have also seen the ones that take mix, but have the full 4-stroke setup. (valves and camshaft). runs like a 4 cycle, lubricated like a 2 cycle.
Click to expand...

zman is exactly right, even though the Stihl 4-stroke trimmers have valves & a camshaft, they are lubricated exactly the same as the 2-stroke- by the oil dissolved in the fuel mix.


#9

I

ILENGINE

The shidaiwa 4 cycle engine use a 2 cycle mix also. the Dolmar/Makita products have a separate oil tank in the bottom with a fill hole.


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