Powerplus or Bust, Eh?

[T. Cotten]

then make the wrist pins heavier

Kevin!

Many folks are using PEEK for wristpin "buttons" instead of the usual retainers, and it would enable you to retain slugs without pressing them and distorting the pin.
(It isn't heavy enough by itself, as filling the whole pin wouldn't be even 30g at most.)

Determining a choice of factor remains the first concern.

....Cotten

[Shaky Jake]

Ooh, that's a lot...

(...but it would get you up only slightly higher than the 64% range of Chiefs with 67%!)

Perhaps it would be easier to slug weight within the wristpins; Top end parts are temporary, the flywheels are not.

It would still be prudent if we had other samplings of original PPs' existing factors.

....Cotten

I could almost talk myself into giving 67% a try, but I might not have been clear; each piston assembly is 215 grams lighter. I think that would put it more in the range of 79.5% (I'm hoping my math is wrong).

The holes in the wrist pins are 2.35 inches long by 0.375 inches diameter. If I slug the pins, that gives me a volume of 0.260 cubic inches, or 4.26 mL, in each pin to gain back the 215 grams. The density of steel is 7.8 g/mL, so if I slug them with steel I can gain 4.26 mL X 7.8 g/mL = 33 grams per pin of the needed 215 grams per pin. Lead weighs 11.35 g/mL, so that would get me a little over 48 grams per pin. It was a good idea, but it's not enough in this case. Remember, the original pistons were made of cast iron.

Based on that, I think I'm going to have to remove some cast iron from the counterweights on my flywheels. I agree with Tom, the first thing to do is decide on a target balance factor. I need to find out if anyone else has determined the balance factor of a Powerplus engine. I wonder if I would get any responses on the AMCA Facebook page? Giving it a try...

Thanks for your input!



Kevin

.

[rwm]

i think you going to make the whole thing to light. your pistons each, are almost half a pound lighter then stock. then your going to lighten up the fly wheels. your not building a race motor.

ps. i have none of the answers just some thoughts.

[T. Cotten]

Golly Kevin,

That's twice as much as I could imagine!

I just dug out the sheet from the last Chief I balanced (2001), and a piston assembly was 667g.

Methinks the eutectics are an issue.

....Cotten

[fillibuster]

i think you going to make the whole thing to light. your pistons each, are almost half a pound lighter then stock. then your going to lighten up the fly wheels. your not building a race motor.

ps. i have none of the answers just some thoughts.

Okay, if this is a 61" motor (ya? no?) it might be reasonable to consider a higher balance factor, as scouts have been balanced in the upper 70's according to VI. ...... Where's the 45 HD balance? on average

[Shaky Jake]

i think you going to make the whole thing to light. your pistons each, are almost half a pound lighter then stock. then your going to lighten up the fly wheels. your not building a race motor.

ps. i have none of the answers just some thoughts.

I agree. For the kind of riding I'm going to do, I want to keep the flywheels heavy. I finally got around to counting the teeth on my sprockets. At my target speed of 50 mph, the engine will be turning about 2170 RPM. I'm not looking for quick acceleration. There are ways to make the other side of the flywheels heavier; tungsten, Mallory, heavy metal, whatever, I'm looking into that. I'll figure it out.



Kevin

.

[Shaky Jake]

Golly Kevin,

That's twice as much as I could imagine!

I just dug out the sheet from the last Chief I balanced (2001), and a piston assembly was 667g.

Methinks the eutectics are an issue.

....Cotten

I hear you, but I'm not sure what to do with that information. My original cast iron piston assemblies are less than 600 grams. At my request, Arias made the new pistons heavier than normal my machining less material off of the pin bosses and the underside of the dome, but in the end aluminum weighs almost a third of what cast iron does.



Kevin

.

[T. Cotten]

Its a shame Folks,

That we left all that depleted uranium on the battlefield.
Or did we?

I'll never forget cracking a 101 flywheel; cast Indian flywheels were probably not so brittle a century ago.

....Cotten

[Shaky Jake]

Okay, if this is a 61" motor (ya? no?) it might be reasonable to consider a higher balance factor, as scouts have been balanced in the upper 70's according to VI. ...... Where's the 45 HD balance? on average

Yes, 61ci. My understanding is that higher balance factors are generally used for higher RPM motors. Some people are telling me I should use a 52% balance factor. I'd be most comfortable if I could get back down around the original 58%.


Thanks everyone for all the thoughts and input on balance factor. Keep them coming if you've got more. In the end, I'll do what I can to balance it the best I can, but I don't think it would be a deal breaker if I have to build it with a higher balance factor. It'll work out.

Also; tell me if I'm off base here, but I think that longer rods make the balance factor less critical, because of lower peak piston speeds, correct? The rods on the Powerplus are 8 inches center to center...



Kevin


.

[Shaky Jake]

One way of looking at it is that it is dependant on the rings as they are the true circle item. It is easier to get the bore to match a standard dimension because rings will be available. The people who make the pistons will usually cam grind them to the appropriate clearance. So the bore might be 3", so the rings will be for a 3" bore and the pistons made with (example ) .004" clearance for the bore.

I almost missed your post Captk, in the middle of all the balancing discussion. There is some room for variance in ring sizes, as long as you set the gap right. In this case I'm using 80mm rings that were commercially available. My 3.125 + 0.020 inch cylinders work out to 79.88mm, so I'll have to file the rings to get the correct end gap.



Kevin

.

[rwm]

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.

[panthersteve]

Hi

I have had a bit of experience with the situation you now find yourself in although not with an Indian. Mine was a 1914 P&M (see avatar).

This too originally had a cast iron piston which I wasn't able to use so a new aluminium piston was made. Now I can't recall the figures (they are at home) but the change in balance factor was significant (like yours). I did have an advantage though, I knew someone who had to do the same thing and surprisingly enough his calculated before and after balance factors were near identical to mine. He said that his engine ran fine and suffered no vibration so I decided to put it together with no alteration to the crankshaft and mine too also runs fine.

My engine is a single which I believe would make it more susceptible to vibration than your twin.

It is my belief that these low performance applications are not at all critical when it comes to balance factor, it is only when an engine is required to run at high revs that this becomes an issue.

If I was you I would put it together with the new pistons, don't change/drill the crankshaft and see how it goes.

Cheers
Steve

[Shaky Jake]

Hi

I have had a bit of experience with the situation you now find yourself in although not with an Indian. Mine was a 1914 P&M (see avatar).

This too originally had a cast iron piston which I wasn't able to use so a new aluminium piston was made. Now I can't recall the figures (they are at home) but the change in balance factor was significant (like yours). I did have an advantage though, I knew someone who had to do the same thing and surprisingly enough his calculated before and after balance factors were near identical to mine. He said that his engine ran fine and suffered no vibration so I decided to put it together with no alteration to the crankshaft and mine too also runs fine.

My engine is a single which I believe would make it more susceptible to vibration than your twin.

It is my belief that these low performance applications are not at all critical when it comes to balance factor, it is only when an engine is required to run at high revs that this becomes an issue.

If I was you I would put it together with the new pistons, don't change/drill the crankshaft and see how it goes.

Cheers
Steve

Steve, I was just talking to Brad on the phone and he mentioned that suggestion also. I think that is the best idea I've heard in a long time. I can always take the engine apart and drill holes in the crank if it vibrates too much, but maybe it will be fine. If nothing else, we will get some interesting data from the exercise.

Thanks for posting!

Kevin

[Tom Lovejoy]

Lee Standley used 55 % on my SS engine and I just talked to Johnny Eagles, he as done a lot of Power Plus and other engines. He said he used the same formula for all the twins, no difference as far as Chief, Scout or early Indian twins. Just some adititional info :-)

[T. Cotten]

Folks,

As was discussed in the VI article,
Choice of factor is more of a tuning technique than a vibration control technique. When I worked out of a speed shop in the early '80s, the universal choice of factor for H-Ds was 52%, but by the turn of the century, 60% became carved in granite. (T&0 and S&S now preach the 60% factor no matter what the motor or stroke, even Indians with the different cylinder angle.)
That's a big spread, but lo and behold,.... all motors ran "smooth" anyway (if everything else was in order).

Having my own machines (Panheads) at both ends of the spectrum, and a factory balanced machine at ~56%, the differences were only in the character of the motor's performance.
The low factored motor jumped like a scalded dog, but never wanted to stop accelerating and cruise. The high factored machine wasn't nearly so spunky, but could cruise comfortably at any speed. The factory machine was right in the middle, where we should expect it to be.

Please note that Matt E. in the VI article back-calculated 82% for an SS, whereas Tom's is 55!
In other words, choosing a factor makes it sound more "balanced" when you talk about it.

What bothers me about the PowerPlus is the lack of a top motor mount.
When H-Ds lose the top motormount bolt, the vibration is quite noticeable; Replacing the bolt re-balances the motor!

....Cotten