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#489078 - 06/16/06 02:10 AM Twin cylinder engines--V, opposed, or inline?
GT Mike Offline


Registered: 12/27/03
Posts: 752
Loc: Oshkosh, WI
What do you prefer for a small-ish garden tractor? I see most, if not all, manufacturers are going to a V-twin configuration, but the ones that I've looked at on new machines from Briggs & Stratton and Kohler aren't all that impressive, IMHO.
The Kohler Command 25 that I ran a while back seemed reminiscent of a Harley-Davidson engine. I wasn't sure at first if it was hitting on both cylinders or not! It didn't have nearly the smoothness that the old KT series Kohler opposed twins had. Makes me wonder if they're not using a common crankpin just like a H-D engine. They sure feel like it. With that configuration and a 45 Vee, the firing pulses will be odd every other revolution, which is exactly what it feels like.

The Briggs felt smoother, but still rough compared to an opposed or inline design.

Honda's inline twin and 3 cylinders are smooth as butter, but water cooling I'm sure helps keep the noise level down a ton.

Just some random observations.

Edit: BTW, what ever happened to Onan engines? They used to be as popular as Kohler and Briggs, and now you hardly ever see one on a new machine.
That was another engine I really liked.

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#489079 - 06/16/06 02:46 AM Re: Twin cylinder engines--V, opposed, or inline?
JR Offline


Registered: 08/08/04
Posts: 923
Loc: Michigan born but my heart bel...
I am not to sure what really happened to Onan engines. I have noticed the same thing, I do not see alot of them on new equipment. I have an old 20.0 HP onan CCKB on a generator/welder. It is old and has seen its share of work, but continues to start run and be reliable. It sat in my garage for several years before I decide to see if it even ran. I pulled the filter bulb and cleaned it. Sprayed the carb down with cleaner. Changed the oil with Pennzoil ll 15W-40. I poured gas in it and cranked it. Two squirts of starting fluid and it was running. It has a sound all of its own. Thump-Thump. Andd is surpricingly smooth. I run it for half an hour to an hour the time it takes me to mow the yard everyweek. I do that to keep water out of the oil and keep fresh gas in it and to charge the battery. Like I said. It runs great. It makes all the power you can ever need. I run it as a back up gen and I have never had a load that has made it sweat. It is gettin tired on one cylinder the left one. It smokes alittle on start up and under load and up to speed. It doesnt use a lot though. I ran it last july for two days straight. It has three throtle settins and I set it in the middle. It only used about a quart, maybe a quart and a half. in two days of non stop running. By the way this engine holds 4.75 quarts of oil to the full line. The manual says it takes 4 quarts.

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#489080 - 06/16/06 03:54 AM Re: Twin cylinder engines--V, opposed, or inline?
GT Mike Offline


Registered: 12/27/03
Posts: 752
Loc: Oshkosh, WI
My Kohler KT17 consumed a small amount of oil since it was new. It was stated in the manual that this was normal. It never really produces any visible smoke, but it does use about a half a quart per 50 hours. This one holds 1.5 quarts of oil, and has no filter. I always toyed with getting the filter kit for it, but since it doesn't get used as much anymore, I figured there's no reason to bother. I retired it from lawn duty when I got my Ariens Zoom 1740 zero-turn rider. It mows much better, and with the mulch kit installed, there's no more windrows of clippings to sweep up.
The deck was getting pretty tired on the GT17, and one of the baffles rusted off, messing up the discharge effect, so it just kind of windrows the grass about 2 feet out of the chute now.
It now serves roto-tilling and snow blowing purposes only.

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#489081 - 06/16/06 08:09 AM Re: Twin cylinder engines--V, opposed, or inline?
Cujet Offline


Registered: 02/15/03
Posts: 4177
Loc: Jupiter, Florida
It is impossible to get good balance out of a V twin or parallel twin. Honda does some tricks to the parallel twins (counterbalance shafts) to get them smooth.

Common crankpin twins are never great.

The Onan style opposed twin (like a BMW motorcycle twin) do not have a common crankpin. The pistons rise and fall together. This does a great job cancelling out vibes. However a rocking couple remains.

Opposed engines are great.

Chris

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#489082 - 06/16/06 08:35 AM Re: Twin cylinder engines--V, opposed, or inline?
GT Mike Offline


Registered: 12/27/03
Posts: 752
Loc: Oshkosh, WI
quote:
Originally posted by Cujet:
Opposed engines are great.


I love my KT17 Kohler! Power seems much smoother than a V-twin of even higher rated HP. A friend of mine has a similar Ariens garden tractor with the Kohler Command 25 V-twin, and when the PTO is engaged for the mower, the engine bogs considerably more to get things moving. I'd be willing to bet my 17 has a higher torque rating, but I've never been able to compare actual HP and torque graphs, as the KT series is discontinued and information about them is getting scarce.

The Command 25 always sounds like it's got a miss, but checking things out, it is actually hitting on both cylinders.

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#489083 - 06/16/06 10:25 AM Re: Twin cylinder engines--V, opposed, or inline?
Chispas Offline


Registered: 12/30/05
Posts: 77
Loc: North Richland Hills, TX
V-twins vibrate even with counter-balancers....

It's not an inherently good design....

Yes, an opposed twin does have rocking-couple....

That's just the inertia of the flywheel, which

is unavoidable....

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#489084 - 06/16/06 05:45 PM Re: Twin cylinder engines--V, opposed, or inline?
Brett Miller Offline


Registered: 09/09/03
Posts: 2636
Loc: Arizona
Onan opposed twins are some of the best small gas engines ever made (in my opinion). I think emissions standards and price have put them out of the market. Some replacement engines are available but are quite expensive. My Dad has a Wheel Horse tractor with a 20hp Onan. It has about 950 hours on it and runs like new.

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#489085 - 06/16/06 07:56 PM Re: Twin cylinder engines--V, opposed, or inline?
JTK Offline


Registered: 08/14/03
Posts: 7300
Loc: Buffalo, NY
In my applications, OHV V twins always kicked-butt over any flat head opposed twin in regards to power & smoothness. You cant buy new flat head opposed twins anymore due to emissions regs. Opposed twins always sucked a horrendous amount of gas and cause everything in a one acre radius to wreak of gasoline. [SPAZ!]

Joel

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#489086 - 06/17/06 07:11 AM Re: Twin cylinder engines--V, opposed, or inline?
80caprice Offline


Registered: 08/09/05
Posts: 194
Loc: N.C.
quote:
Originally posted by JTK:
In my applications, OHV V twins always kicked-butt over any flat head opposed twin in regards to power & smoothness. You cant buy new flat head opposed twins anymore due to emissions regs. Opposed twins always sucked a horrendous amount of gas and cause everything in a one acre radius to wreak of gasoline. [SPAZ!]

Joel

Not mine..... I had a B&S flat head apposed twin 18 horse.... quite powerful, and the one gallon gas tank would last a good 4 hours... it was a powerbuilt with cast iron sleeves.... got rid of it since the mower itself was rusty and falling apart (but the engine still ran like new)

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#489087 - 06/18/06 05:36 AM Re: Twin cylinder engines--V, opposed, or inline?
JTK Offline


Registered: 08/14/03
Posts: 7300
Loc: Buffalo, NY
One gallon lasts you 4hrs of mowing at full throttle? On a 18hp flat-head twin briggs?? That's a miracle engine!

Joel

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#489088 - 06/18/06 08:29 AM Re: Twin cylinder engines--V, opposed, or inline?
80caprice Offline


Registered: 08/09/05
Posts: 194
Loc: N.C.
Well I cut the yard in the highest gear..... (and the grass at that time wasn't too thick) and of course, the 48 inch deck on it helped as well. Usually took me 2 hours each cutting.... on one tank... (atleast I beleive it was a one gallon, might have been a 1.5, its been so long ago)

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