Are 3 cylinders better than 2?

[284 International]

When I was working on my YM240, I ran it without the muffler on it. It didn't really seem much louder than the engine did with the muffler on. My three cylinder machines of all makes are much smoother, and quieter, than their two cylinder counterparts of different brands. My Kubota is the most civilized of the two bangers; it's rather smooth, and is just a darling of an engine, and fairly quiet. The big Yanmar 2 cylinders, though, are just plain loud. Even with the garage door shut around the exhaust pipe in forward configuration, the engine block itself is producing a lot of noise. A larger muffler may help, since it currently doesn't really do much, but I don't think it will ever "purr."

They are all, in any configuration, too loud for me to use without hearing protection. I wear ear protection with all of my power equipment except electric drills. Even my vacuum cleaner is too loud for my taste. With the big Yanmars, I wear plugs and muffs in combination; anything else just hurts.

I prefer the two cylinders though, strongly. I like the flatter powerband and increased low-end torque. Since they're all too loud, I'd rather have the user-friendliness.

 

[Pete Judd]

I have heard, and also noticed that most of the noise from a well mufflered diesel is from the injection pump. On the boats, with wet mufflers, there is no noise out side of the injector pump. On my detroit 2 cycle diesel in the motor home, the injectors are pump type, one injector with piston driven from a cam lobe at each cylinder. Most of the noise comes from under the valve covers where each of the mechanical injectors live.

Years ago I lived above a shop that did nothing but service and rebuild pumps and calabrate injectors. When they put them on the test equiptment, it sounded like the engines were running downstairs.

 

[Car Doc]

Glad to have the 3cyl its smooth running all around.

I am a little over sensitive to engines that are not smooth its my business so its a hit (3 cyl) as far as I am concerned.

 

[California]

Aside from the racket I think the firing order of the 2-cylinders is unsettling too. One cylinder fires 180 degrees after the other, then it coasts for another 540 degrees before it fires again. It doesn't 'sound right'.

(The reason it's designed this way with the rods on opposing crank throws is to maintain constant crankcase volume. A crankshaft with both rods on the same crank throw, like an old British motorcycle, sounds nicer but it pumps a lot of oil out the breather and would probably suck in a lot of dust too.)

Oh well. All that racket is the sound of Raw Power!

 

[deepNdirt]

a 2 cylinder hammering out the power doesn't necessarily mean that its doesn't run smooth, I personally haven't felt anything that indicated a rough running engine with the 2 cyl. Its not like riding a Harley Davidson that shakes you while holding the handlebars, although I've read where some has stated their 2 cyl. will jar your teeth out, as much as I use my tractor
( several hours each day) sometimes 5-8 hours, If it felt like I was being beat-up by it I certainly wouldn't be owning one, I do however wish sometimes I had a bit larger of a tractor so that I wouldn't have to be using my tractor as i would a large one

 

[Ginormous]

I was running mine a little while ago (testing out the rear wheel on the rotary mower) and paid more attention to the volume and smoothness. It's a far cry from a smooth running car, but I would say again that it's not that loud and runs very smoothly, especially above 2000 RPMs. Maybe I got a good one.

 

[California]

not that loud and runs very smoothly, especially above 2000 RPMs. Maybe I got a good one.

You got a good one! (or maybe you have excellent hearing protection? :laughing: )

Mine sounds like its going to scatter from 1800 on up. That doesn't seem to hurt it but it's not calming.

 

[deepNdirt]

I was running mine a little while ago (testing out the rear wheel on the rotary mower) and paid more attention to the volume and smoothness. It's a far cry from a smooth running car, but I would say again that it's not that loud and runs very smoothly, especially above 2000 RPMs. Maybe I got a good one.

ya know not many of us here own the Ym1700 ..... although they're quit a few ym2000 owners here, I'm wondering if the 2 cyl ym2000 are worst about the rough running then the 1700 are!. I know we share the exact same engine ( 2tr ) the only difference is the cylinder bore, perhaps the smaller pistons of our 1700 doesn't quite have such an impact on the way what some are saying they run, just saying!

 

[California]

I'm wondering if the 2 cyl ym2000 are worst about the rough running then the 1700 are!. I know we share the exact same engine ( 2tr ) the only difference is the cylinder bore, perhaps the smaller pistons of our 1700 doesn't quite have such an impact

Good theory, and it sounds quite likely. Surely the smaller pistons would be in better balance.

 

[284 International]

I'm interested to hear anyone's comparison between a 2210 and the 2000/240 along the theory of the larger cylindered engines making more noise. I believe it, since one of the principles of muffler effectiveness, whether a silencer on a firearm or on an engine, is having a large volume relative to the "bang" going on to quiet and subdue the noise. I would imagine the 2210 is louder, if that's possible, than the 2000/240.

Hoye's part number is the same for the crankshafts for both a YM2000 and a YM1700. I guess I'm used to high rpm bike motors and car engines, where a change in bore size, even by fractions of a millimeter, is something to fret about, since it changes the balance of the reciprocating assembly. I guess the lower rpm and more durable lower end of these machines make it a non-issue.