80" lightened flywheels balancing

[T. Cotten]

CDF6333!

Please remember that H-D used a factor closer to 50%;
(I just back-calculated a '55 FLH to 52%.)
The differing cylinder angle, as well as different frame mounting, calls for a different optimum factor (as explained by Herr Elvenkemper in the VI Flywheel Workshop discussion.)

Please note also that H-D went to a grossly larger left flywheel, without issue. Making the two wheels equal makes one feel good, but it really isn't in the basic balancing formula.

Neither is total flymass, but the need for 'stored torque' is why H-D did it. Lightening the total flymass allows for quicker acceleration into the peak horsepower range, but it is a trade-off.

In my attachment, you can see where a 101 flywheel has been set into a lathe chuck, and sitting in a pan of oil. Over it has been placed a clear acrylic box. Note the lines of oil sprayed upward from the sides of the wheel, but little or none from the outside diameter of the wheel.

Reducing the 'windage' area of the wheels reduces their ability to pick up sump oil to be scavanged by a scraper. So radical shaving of the wheels should be reserved for competition machines, and not daily workhorses.

....Cotten

[cdf6333]

OK, I'm going to rephrase my question to do 2 things. Firstly, I want this engine to run fairly soon and well. Secondly, I'd like to forward this info to the people after me who can make a set of parallels and aren't going to get into "reciprocating weights" and the like. I'd guess that 99% of the V-twins, HD and Indian will be more than acceptable using the S&S recommended static balance, especially since every time you take apart the flywheels, you're destroying the tapers, which have a limited life.
Has anyone static (parallels) balanced an 80" Chief with lightened flywheels? (I, for the last 40+ years, have gotten acceptable results balancing regular 74's and 80's both like a HD, 1 piston assembly, and like Military Indian and Franks Q&A, 1 assembly plus 1 -4 ounces.) The last 80" I did was about 6 years ago, belonged to Al Kelly of NJ. (It came in to me HD type, 1 piston assembly and I redid it that way) This was the smoothest AND fastest Indian I ever did. He sold the bike but it is still roaming NJ roads. If every engine I do came out like this, I'd be ecstatic!
Thanks to all, especially Cotten for the info.

[T. Cotten]

CD6333!

Your thanks is welcome, and please take this politely:
There is no point of building parallels or 'knife-edges" if you are not going to 'get into "reciprocating weights" and the like'.
They are pointless without them.

And I agree tapers can suffer.
That's why I suggest lapping each and every one: http://virtualindian.org/10techfly.htm

A machine can run smooth and reliably over a very, very large range of factors, as that depends far more upon a true and sweet assembly than its balancing. This forgiving aspect is what made V-twins the legends they are.
(My belief is that balancing a V-twin is a tuning technique, and that the motor's character is determined by the factor, something that multi-throw motors cannot easily vary.)

So if you are in a hurry, by all means, put her together!

...Cotten

[cdf6333]

Thanks Cotten. But I think you're wrong on the balance as tuning. I think the balance compares more to wheel truing and centering, ride-ability.
I'll bet that over the years the vast majority of all V-Twins were done on parallels using the piston assembly and a drill press, successfully. Good enough, sometimes is good enough.
As for lapping, I wouldn't lap anything. As a 40 year auto machinist, we found that the compound, oil or water. never left he softer metal.
This engine has 2 pinion side wheels, probably lost the one when the 80 rods disappeared years ago. Had to under cut the end of the crank pin and drive shaft as they both protruded thru the tapers. Used shim washers under the nuts, as Indian nuts don't like this. HD nuts had a washer face so it would "cover" a protruding shaft.
Again, this motor was engineered fine using 50's tech, I just want to make sure that I don't "un-engineer" it, by doing something stupid.
Thanks for the articles, I can see that a lot of thought and work is going into our hobby.

[T. Cotten]

CDF6333!

I come to my conclusions not by the armchair, but by the seat of the pants upon a wide selection of very similar machines with greatly varied factors.

(Albeit they were Harleys.)

A true-and-sweet assembly is just that, and will run smooth over a wide range of balance factor.
A low factor, however, gives the character of wanting to accelerate rapidly, and never stop.
A high factor isn't such a scalded dog, but wants to cruise comfortably wherever you put it.

That makes balancing a tuning tool for our single-throw motors.

....Cotten

[cdf6333]

That's kinda what I was searching for, thanks again. I think, and I'll wait a day or two more, That I'll remove 2 ounces from the crankpin side. This will still be under 1 piston assembly weight, but this new owner, while wanting to keep the bike as it was originally done, isn't going to race any Harleys ( I hope). But I want to improve his comfort without changing all the mods Jules did 50 years ago.
I've never balanced an engine below 1 piston weight, so this will be new ground. I will post the results in a couple weeks when he picks it up.

[cdf6333]

Dennis got the Chief together yesterday, Runs great and fast! I'm posting a few pics of some of the cool $hit.
Dual exhaust, front pipe goes under.
HD big block manifold nipples, manifold and 1 1/2 " - 4 bolt carb
foot shift hand clutch with the $hitty mousetrap, doesn't look homemade. The parts pressed into the primary look machined professionally. IMG_0344.JPGIMG_0346.JPGIMG_0348.JPGIMG_0349.JPG

[cdf6333]

two pics didn't go. I'll try againIMG_0345.JPGIMG_0350.JPGIMG_0351.JPG