Traverse 4 VS Vtwin

[Larrym]

Degrees of Separation

Motorhead,

Just grabbed the biggest straw that was sticking out there in the open: vibration and the forces/parts which cause it.

Less than four feet away from me now is an engine that really opened my eyes/ears to the whole "push the performance envelope" when it comes to engines. It's a yanmar 2GMF "Diesel". What I mean is that it runs on diesel fuel but instead of running at the low rpms which give the "ordinary" diesel engine its longevity, this little powerplant runs at a 3400 rpm in continuous duty.

At idle speeds the motor is as close to a "shaker" as I've ever seen. So much so that the engine mounts have to be like huge rubber marshmallows. (Wish I could provide a video for ya but the engine is mothballed for the winter...) It's kinda scary it moves around so much. But the engine appears to "smooth out" at the 3400 rpm. Key word is "appears".

Thing is that the forces of the pistons/crankshaft counterbalances which cause vibration are even greater at the higher rpm. What makes them appear to go away is the combination of the vibration dampener/flywheel spinning at the higher speeds. Sorta like how a spinning gyroscope resists being moved if you push on it. The forces on all the internal moving parts/bearings/etc are still there.

Problem is sorta the same as the big v-twins though: Higher rpms with longer strokes and bigger parts at the end of the connecting rods. Performance is great. I mean the little Yanmar with 12.5 HP outperforms a larger gas engine with better fuel economy. But it's how it achieves this feat that troubles me.

I'd like to believe that the v-twins (along with my little Yanmar...) are over-built with parts which are more than equal to the task. The track history of other Yanmars like mine just doesn't show that. (V-twins??? I dunno.....)

Let's keep our eyes and ears open for the next 20 years. (I'll be 71 by then...) By that time we'll all have some history of the v-twins: how they died, why they died. How reliable will the v-twin be? Just like the history of the XS1100. I mean there are some XS's still on the road but there's a lot to be learned by examining the ones that are no longer running.

[Pat Kelly]

An inherently balanced engine not mentioned here is the inline 6 cylinder. Crank throws are 120 degrees apart with 2 countering each other (balanced vertically and horizontally 'and' laterally, front to back).
So, if you have 1 and 4 rise together and 1 is on power as 4 is on intake, then 2 and 5 follow 120 degrees later, then 3 and 6... no crank counter weights should be needed.

[motorhead]

larrym
so you're a Sailer
As far as history of a v-twin ,do you not think the've been out there enough years to get a grip on reliability.There are many other v-twins than Harley .But to use HD as an example,when they went to the evo motor (early 80's i think)they moved up to a hundred thousand mile + motor.Most of the newer v-twins are pretty damn reliable.I just don't think you're going to find any of the newer v's less reliable than a inline 4.And the inline 4 is more complex,so it stands to reason it will take longer to repair .It will probably cost more since there are more parts.My gut would tell me the motor with the most complexity,and parts would be down more often.Now if we compare vintage V-2 to I-4,Most v-twins built before 80 or so were terribly unreliable bed wetters.What years of what are we comparing.?
And I have watched 2 cyl Yanmars "dance" on the stringers .
The little one lungers will really get you moving

[Larrym]

History Reveals.....or maybe Not.

Motorhead,

"What years of what are we comparing.?"

My best guess would be not the "classic" v-twins of yesteryear. More along the lines of the newer "non-domestic" models with the big pistons. If we get this wrong then Rickrod3 can buzz in and point us to somewhere else.

Correct-a-mundo! I do love that moment when I pull the stop cable on the Yanmar and the sails take over. Note: failure to retorque the cylinder head every 300 hours of operation on those Yanmars is quite costly....

So about those newer v-twins..... I'm going to extend the benefit of the doubt to those little Japanese guys in their labcoats. Historically they've done a fine job of taking the motors in cars and doing their Kung-Fu on 'em. Results were that in the 70's they almost put detroit on notice by making engines/cars which had better "numbers." ( Better Mpg, less downtime, more reliable, etc....) Taking something we were doing and then refining it, optimizing it, and selling the finished product back to us.

We're talking about better/different quality control in the manufacturing process, closer tolerances for the individual parts, better materials also. I'll concede the point that when these same or similar people and methods focused on the task of putting out a V-twin that it had to be way better than what was available before they took their turn. More reliable: Yes. As reliable as an inline 4:???

That's where things get awkward. I recall when those Japanese guys were putting out bikes in the 60's and 70's. (All of them: Yamaha, Honda, Kawasaki, etc...) They made 1 cylinder 4 strokes/2 strokes, 2 cylinder 4 strokes/ 2 strokes, 3 cylinder 4 strokes/2 strokes. By the time they made a 500 cc it was clear that they had a "Harley-Killer." (And with better "numbers" for cost, reliability, etc...) But after making that "killer" what else could they do? I say they continued to compete honorably amongst each other with more cylinders/more cc's. One happy day in 1978 Yamaha came out with what every one expected to be a 1000 cc inline four cylinder but surprised everyone by having 100 cc more. ( Not likely that the design team did fist bumps or chanted "Who's your Daddy now!" Just not their way...)

In this period of time "they" (labcoat guys with slanted eyes...it's a good thing!) tried different types of motors: Wankel, upright singles and twins, even a 90 degree twin where the cylinders extended up and out the sides of the bike. Water cooled, air cooled. They were all over the place.

Not really all over the place. The one type of engine that none of them put out was the V-twin that we see today. Not that I can recall. In their quest/competition for performance, cost, reliability, handling, etc., the v-twin never made it to production.

I gotta ask just why that was the case. Got my educated guess...What do you guys think is the reason for that? I mean the v-twin is conspicuously absent during that time of "friendly" competition between the Japanese bike makers.

[Larrym]

Complexity

Motorhead,

"My gut would tell me the motor with the most complexity,and parts would be down more often."

I agree. Well, uhh...that's true most of the time. In this case the added complexity of the inline four has a purpose: to reduce the vibration/forces which would otherwise cause failures of other parts. It's more of a "justifiable engineering" cost/reward thing.

These additional parts still have to do their job/not fail. When they eventually do need to be replaced then the true cost is a matter of how innovative/resourceful the owner/mechanic is. Going to the dealer for parts/labor is gonna hurt no matter how many cylinders one has.

[hamjam]

some japanese Vtwins

honda vtr, Dn01 Varadero
suzuki v strom SV650SA SFV 650 Gladius

[motorhead]

I think it's a given that the V-twin is an antiquated design.Why did the Japs go V-twin .Because that's what Americans were buying,and they wanted a piece of the cruiser pie.Big Pie.The obvious design advantage is the slim packaging ,which is why the initial v's were tried and used in this country .I have now, and have had several V-twins thru the years.I like all bikes .I had some of those early jap bikes when they were new .72 H-2 750,enjoyed that wheelstanding beast .1's 2's 3's 4's,never had a 6. I like them all.If it'll run ,I'll ride it .When I own something ,it becomes more reliable .Just saying.And have a good day

[Rickrod3]

My best guess would be not the "classic" v-twins of yesteryear. More along the lines of the newer "non-domestic" models with the big pistons. If we get this wrong then Rickrod3 can buzz in and point us to somewhere else.

Like most of us I like all types of bikes. I owned a Harley once. Being a person who has to and enjoys maintaining bikes; I have experienced both having there good and bad points. I just wanted to know what those were based on the vast experience that is in this forum.

BTW I have found the thread to be very interesting.
Opinions are based on that persons experiance so; weather it has been yours or not there is something to be learned.

Thanks
Rick

[fredintoon]

Urban legend?

Larry, the radial engine was never known for balance. they had single throw cranks. If two pistons on a single throw crank are bad, think of 7, 9 or even double that in twin bank engines. The whole ring of pistons moved as one mass and they shook like a wet dog. Now on the beloved Camel and some other early WWI fighters, the crank was actually mounted to the frame and the whole engine spun, cylinders and all. The thought was to keep it cool, and was later found to be unnecessary. The engines that spun had no throttle, just an ignition switch. So that's why the old movies of those airplanes landing had a brap...brap.....brap..brap......brap sound, since the pilot was flipping the ignition switch on and off. Since the pistons on those stayed fairly stationary, they were very smooth. Well, according to my Grand father that flew a couple like that waaaaay back in the day.

Hi Ivan,
I used to build the bastards. Bristol Hercules 14cyl & Bristol Centaurus 18cyl. On a single-bank radial the engine CG twirls round in a little circle and don't notice that much, the master rod/articulating rod set-up lessens the effect too. The twin-bank radials have the crank throws at 180º to each other so they cancel out.
There's a story that as those WW1 rotaries were lubricated with castor oil and exhausted straight out the head the pilot was stuck with breathing the castor oil laden exhaust fumes and thus was forced to run for the outhouse immediately on landing. If your Grandpa is still with us, could you ask him if that is true or just another urban legend?

[motorhead]

Hi Ivan,
I used to build the bastards. Bristol Hercules 14cyl & Bristol Centaurus 18cyl. On a single-bank radial the engine CG twirls round in a little circle and don't notice that much, the master rod/articulating rod set-up lessens the effect too. The twin-bank radials have the crank throws at 180º to each other so they cancel out.
?

I get a kick out of radials.One of the coolest looking motors there is .Used to be one out at a local airport that was for hire for siteseeing .Where the plane was parked there was a well marked grease and oil spot.I walked over to look at the motor up close in time to see the pilot tightening some kind of brass oil line,using his crescent wrench.Looking at all the oil on the ground ,then sizing up the pilot ,I went to the bar .

[hamjam]

Hey Motorhead did you look at the Vtwins that I posted wicked nice and not cruisers
Jim

[fredintoon]

Hi motorhead,
you said "?" Here is the wiki site on how radials work:-
http://en.wikipedia.org/wiki/Radial_engine
The animation shows the single "master rod" and all the "articulating rods" that are connected to it.
The twin-bank radial has it's rear bank offset half a cylinders-worth from the front bank so the rear cylinders see some cooling air and it's crank is set at 180º to the front crank.

[hamjam]

ooh thats a sexy beast ai

[motorhead]

Fredintoon
That is a cool radial link .Couple of those motors will be spinning over on my desktop with wallpapermaster.

[Larrym]

Too Negative??

Rickrod3,

Thanks for clarifying the motor type. For a while there it was a little confusing.

More Clarity: I'm not anti V-twin or anti-Harley. I am anti-Failure. Don't like it at all when any type of engine goes clunk and makes the bike it's in nothing more than a lawn ornament. Looking at any motor with a critical eye and finding out how they're built and how they fail can give information so you can either get ahead and stay ahead of stuff or deal with the failure in a more efficient way.

I've had a lot of different type of bikes/engines. Treated them all with TLC in a "Why ya running poorly, little feller? Show me where it hurts and I'll make it all better...." way. I'd do the same for any big v-twin. Just one of those character traits which started at a young age....

The whole "pick it apart" and find out every problem it has mentality comes in really useful when a non-running bike arrives at your workshop in the back of a truck. Doesn't make for a good bedside manner though.