Author Topic: H-Beam rods  (Read 1265 times)

Offline coater87

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Re: H-Beam rods
« Reply #15 on: 29.05. 2017 09:24 »
 Ok,

 I am wondering if it is worth the effort to balance this.

 I have no idea what the factory balance factor was. If I go through all this can anyone agree on a specific balance factor percent?

 Example, I know a bit about iron head sportsters. One guy claims 54 percent, the next guy is around 72 for the same motor.It seems you cannot find two people who agree on this kind of thing.

 What would be a good factor for a smooth motor running in the 2500 to 3500 RPM range?

 Lee

Central Wisconsin in the U.S.

Offline muskrat

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Re: H-Beam rods
« Reply #16 on: 29.05. 2017 10:49 »
G'day Lee.
I think it was 54% std and 60% for faster speeds. So stay between those.
I went up to 72% in the A7 racer. Smooth as silk at 7500-8000rpm but at idle she'd want to walk out the door and up to 5000 rattle my teeth out.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Muskys Plunger A7

Offline coater87

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Re: H-Beam rods
« Reply #17 on: 29.05. 2017 10:56 »
Dutch,

 I suppose there are a lot of things that go into ARPs decisions on these bolts. Maybe thread form is one of them. *dunno*

 I do believe these rods are way over kill for how I intend to use this motor though.

 It does give me one less doubt as far as using the old mismatched  set I had.  I had two left hand rods, because  I could not salvage any right hand ones.
Central Wisconsin in the U.S.

Offline duTch

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Re: H-Beam rods
« Reply #18 on: 29.05. 2017 11:41 »

 Yeah Coater- much the same decision I had to make at the time- just thought I'd better bring it up, not that it probably matters much
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline coater87

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Re: H-Beam rods
« Reply #19 on: 30.05. 2017 13:22 »
 I can find nobody who does any dynamic balancing on anything but Harley.

 So I thought I would do this myself. I looked for a static balance stand because I dont own one, S@S makes one for $1300.00 U.S. *eek*

 I think what I am going to do is weight up what I have stock and figure it at 56%. Then weigh up the new stuff and see (if the math can be done) where my balance factor will be and go from there.

 Lee
Central Wisconsin in the U.S.

Online KiwiGF

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Re: H-Beam rods
« Reply #20 on: 30.05. 2017 22:31 »
In the link on my earlier post the std balance factor on a small journal (SJ) crank came out about 50%, and I found using some non std components only altered it by a couple of per cent, so I left the crank alone.

I found some really heavy gudgeon pins during the weighing exercise! (These should be avoided........)
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Offline coater87

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Re: H-Beam rods
« Reply #21 on: 02.06. 2017 17:21 »
 After weighing things the best I can (will post figures later) I decided balance was not going to shift enough to bother. Odd thing was the stock little end weighed more than the MAP little ends. I never would have thought that.

 Instead of pulling to 30 pounds this time, I used a micrometer. At 25 ft. lbs. I had .0053 (shortest) and .0057 (longest) bolt stretch. So I am going to say 25 Ft. Lbs. is good for MAP steel rods, I cycled the bolts (30 ft. lbs. torque and back to zero) 6 times in total.

 Lee
Central Wisconsin in the U.S.

Offline muskrat

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Re: H-Beam rods
« Reply #22 on: 03.06. 2017 09:28 »
G'day Lee.
Sounds like you got it nailed. Always go with the recommended figures.
With my R&R rods at 30Lb/" they locked up but at the recommended 50Lb/" for their rods and ARP bolts they freed up nicely.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Sluggo

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Re: H-Beam rods
« Reply #23 on: 24.06. 2017 08:30 »
I can find nobody who does any dynamic balancing on anything but Harley.

 So I thought I would do this myself. I looked for a static balance stand because I dont own one, S@S makes one for $1300.00 U.S. *eek*

 I think what I am going to do is weight up what I have stock and figure it at 56%. Then weigh up the new stuff and see (if the math can be done) where my balance factor will be and go from there.

 Lee

I am NOT going to tell you what to do,, But it should not be that difficult to find a skilled tech who does Dynamic balancing..   I use a guy here in Oregon, and If you like, he WILL accept mailed projects/shipping.  I use a converted plastic milk crate for mine.  He does Airplane propellors and certain types of industrial equip as his bread and butter but he does do motorcycle engines.  Yes,, A number of Harley engine builders use him, and he can make an old pan or knuckle so smooth its like a BMW,, But I have referred a number of people as well as use him myself for British bike engines.

Great job and service.  The thing is, there is an epic difference between Dynamic balancing and static balance.  I liken it to those old bubble balancers for tires you used to see at roadside gas stations vs the spin balancing with digital readouts at modern tire stores.  2 completely different animals.

But you cannot address Rocking couple with static balance.  And, depnding on many factors, most British twins have horrible issues with Rocking couple. 

I also never fixate on speculative balance percentages.  I Blue print all my parts, (Pin, piston, clips,, all checked for even weights,, machined and blue printed rods and crank..  and then we discuss what type of frame, how its mounted, and typical RPMS and types of riding.  I let him setup using that info and whatever he feels best.  Always comes out great. He keeps a notebook and can include his specs so if you had to replace the pistons or something,, You just make sure you come back to the same weights..

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