Powerplus or Bust, Eh?

[exeric]

I am really benefitting from all of the sage advice on balancing. Being a motor dimwit, I've never understood the goals, and principals involved in balancing. Thanks all, for a very educational discussion.

[Tom Lovejoy]

I am with Eric, but find this thread very interesting and I am enjoying it.

[fillibuster]

call truett and osborn. they may have some helpful ideas. they have always seemed nice when i have called them. i can't believe somebody has not jumped in here and said "kevin do it this way for x reason" i quess it's true that indian guys are cheap. they probably wont pay for internet.

I can't talk about the "cheap", but I will chime in about the lack of input from experienced builders. I'd like for this forum to broaden successful preservation practices, be a preferred source for tech info, and it's coming up a little short. Still, I've found it very rewarding, and I have a lot of you fellows to thank, those who have participated. And I found VI too late.
Maybe it's just a funny thing about mechanics, engine builders, maybe with "not telling", who knows?

[djones]

Here is the math, way I see it:

The amount of reciprocating mass that is being balanced by the flywheel counterweights is equal to the mass of both small rod ends plus the amount of weight I had to add to get it to balance in the third video. Arithmetically, that is 198.0 grams + 198.7 grams + 524.0 grams = 920.7 grams.

The total reciprocating mass is equal to the sum of both piston assemblies plus both small rod ends, or 596.3 grams + 594.0 grams + 198.0 grams + 198.7 grams = 1587 grams.

The percentage of the reciprocating mass being balanced by the flywheel counterweights is 920.7 grams / 1587 grams = 0.580

My as found balance factor is 58%.


Discussion and corrections are welcomed!




Kevin

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Kevin,

I finally got a chance to do some checking on my 14 crank. Using the same methods, I got some very interesting results. All indications lead me to assume that this motor has never been apart. Standard bores, original gaskets, and all the original F markings. So here goes..........

Front piston (with rings, pin, cotter pin) = 612 g
Rear piston (with rings, pin, cotter pin) = 608 g
Front rod end (forked) = 167 g
Rear rod = 162 g

Like yours, the 1 piston method was to heavy, so I stung a wire between the conn rods and started adding weight. The balance weight was 578 g. So for my 1914 Hendee Indian, I got

Total recip wt = 167+162+612+608 = 1549g
Balance Wt = 167+162+578 = 907g

Balance Factor = 58%

Coincidental?

Carry on,

Doug

[T. Cotten]

Doug!

Are there any balancing holes drilled into your flywheels anywhere?

....Cotten

[djones]

Cotten,

There are no holes drilled in wheels, eighter in the side or face. Some casting slag remains, and some evidence of grinding on the interior of the webs. Maybe just cleaning up the casting? Leads one to conclude that there may not have been a lot of time spent balancing these motors in 1914. I guess they were capable of getting the castings close enough from the foundry?

[Shaky Jake]

Doug,

Very interesting indeed! Thanks for posting that.

Physics is fun.

A happy and blessed Easter to you all!


Kevin

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[panthersteve]

Cotten,

Leads one to conclude that there may not have been a lot of time spent balancing these motors in 1914. I guess they were capable of getting the castings close enough from the foundry?

This is the sort of info that has lead me to believe that it really doesn't matter too much.

Steve

[BoschZEV]

This is the sort of info that has lead me to believe that it really doesn't matter too much.

I have a very extensive library of motorcycle books (over 3000) so I took a few minutes to see what I could find in early books on the subject of balancing a V-twin. The three-volume "Cars and Motor-Cycles," edited by Lord Montague of Beaulieu and Marcus W. Bourdon (Pitman, 1928), is the earliest I've found so far that deals with it in any sort of technical fashion. Seven chapters of that book are devoted to 'Engine Balancing,' with Chapter IV on 'Single- and Two-Cylinder Engines'. Quoting from it:

Where the included angle is less than 90o complete balance cannot be obtained, but, in practice, counterweights are added, their proportions being determined by trial and error until a combination is arrived at that gives minimum noticeable vibration.
The use of the V-twin engine being practically confined to cheap cars and motor-cycles, where exceptionally smooth running is not essential, most manufacturers content themselves with balancing the primary harmonic by the addition of counterweights to the crankshaft, and ignore the higher unbalanced inertia forces.

From this and other writing in this chapter it's clear that "state-of-the-art" practice in engine balancing more than a dozen years after your Indian was made was entirely trial and error rather than any sort of technical understanding. I should say that although technical understanding did slowly develop, actual practice stayed trial and error for at least the next 50 years since the perceived vibration depends on the frame and there wasn't the computational power to even begin to attempt to model this until fairly recently.

Another point is that, in general, the slower an engine spins the less critical the balance is. Although an unfortunately-positioned mechanical resonance can make things bad at any rpm, an engine that doesn't get above 2000 rpm is a lot less critical than one that sees 10,000 rpm. Out of balance forces go as the square of the rpm so the vibration forces generated by the latter are 25x higher than the former.

[Shaky Jake]

Wow. I would love to see your library.


Kevin

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[fillibuster]

Wow. I would love to see your library.


Kevin

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MMnnnn.... I'm gonna give the earlier engineers a little more credit than that, Mr Bosch. I don't have your library, just a hunch, that they were pretty secretive about "showing their work". Granted, carburetors and cams and porting were stone-age, heat dissipation wasn't respected, but I think they had the tools to move up the technological ladder a little faster than they did. They just didn't have to. All the yuppies were buying their bikes anyway, so why should they build them good enough for the purists?!!

[BoschZEV]

but I think they had the tools to move up the technological ladder a little faster than they did.

Addressing issues like this is one reason books are so useful. They document what was known, when, and who knew it. Actually, most motorcycle innovations didn't come directly from motorcycle engineers, but rather were recognized by the best of them from other industries (often, aeronautical) and quickly adapted for motorcycles.

[fciron]

Phil Irving's Motorcycle Engineering says almost exactly the same thing about v-twin balance factors three decades or so later. The important thing is results and, since the effects of engine balancing are determined by the frame and the engine mounting, it was impossible to make across the board declarations.

[Shaky Jake]

Catching Up

It's been a while since my last post, I apologize. My job is seasonal in nature and spring and fall are the seasons that I work. I'm home now and tinkering with the bike again. If I recall correctly, we were talking about pistons, oil rings, and balance factors.

The balance factor on my engine will be almost 80% if I use the aluminum pistons and don't do anything to the fly weights. That means that almost 80% of the reciprocating weight will be balanced out in the up and down direction, but it also means that the front to back imbalance will be almost 80% of the reciprocating weight. That's more than you would normally shoot for. Some of you, and some other folks I know who also build old motorcycles, have suggested that I just try it. It makes sense to me, based on the gearing the engine will only run at about 2200 RPM at road speed. That's almost idle speed on a modern dirt bike... So my plan is to put it together and see if she shakes. If she does, I take her back apart and drill the fly weights. I'm comfortable with that plan.

The oil rings are food for more thought. The advantage to running modern oil rings is that the cylinders won't carbon up as fast. In reading the literature, it sounds like it was necessary to de-carbon the combustion chambers on these old birds on a regular basis. With modern oil rings, I might never have to do that. I would use a suitable top-end oil or two-stroke oil to keep the valve guides lubrictaed. My concern is whether that will be enough to keep the front cylinder lubricated. Let me explain; the Powerplus engine uses a total loss oil system. As oil is burned, or leaks out, it is replenished by an "automatic oiler" which is a kind of metering pump that you adjust to feed oil in at the same rate that it is lost, so that the level in the crankcase stays in the middle of the sight glass. The replacement oil is pumped in through a port in the front cylinder because the crankshaft doesn't sling enough oil into it. It slings plenty of oil into the rear cylinder, but not enough makes it into the front cylinder, so the front cylinder depends on the replacement oil from the automatic oiler. If I use oil rings on the pistons, not much oil will be lost, so the automatic oiler will have to be adjusted way down, so it doesn't inject much oil (the gusinta has to equal the gusouta). In that situation, the front cylinder won't get as much oil pumped into it as normal. So, will two-stroke oil mixed with the gas be enough to keep the front cylinder lubed? I'm not sure. Some builders chose to not use an oil ring, I can only assume this is the reason why. I know that some builders use oil rings but file some little nicks or notches in them to allow some oil to pass. I've never seen them first hand, just heard talk of them, but it makes sense.

I would be interested in any thoughts or experiences you have on oil rings.

Otherwise, I believe my gas tank concern has been addressed, with the help of some friends. I'll post some pictures of that in my next post.

Cheers and thanks for listening.


Kevin

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[Shaky Jake]

I think I mentioned earlier that I'm concerned about my gas tank. I have two of them, one from a 1914 Indian, and one from a 1916. Both are cracked, but easily repairable. The original tanks are made from fairly thin steel; about .040 inches thick, and the seams are soldered together. Experienced Cannonballers and old bike officienados have told me that the original tanks will not go 4000 miles without cracking, leaking, and potentially burning on the side of the road. My solution came from a friend and experienced Cannonballer in NC. He recruited some local Hillbilly labor (his words, and said with the utmost respect) to build some replica tanks from 16 gauge steel (about 50% thicker than original) with welded seems. Here are some pictures of mine. I had to do some light hand work with a body hammer and file to fit it to my frame, since there seems to be some variations in the frames. I'm happy with the tank, it looks good and feels much more substantial than the original.







It still needs some sandable primer, maybe some light filler, and a little paint. I like the look of my old tank better, but this is a sacrifice I have to make. I'll keep the old tank for non-Cannonball use.


Kevin

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