Author Topic: Crank Balancing DIY  (Read 6108 times)

Online JulianS

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Re: Crank Balancing DIY
« Reply #30 on: 04.01. 2021 18:37 »
For the very brave there is this rather brutal technique from a 1959 bulletin from Hap Alzina in California.

Online Seabee

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Re: Crank Balancing DIY
« Reply #31 on: 05.01. 2021 03:27 »
Wow Julian, we Yanks are some crude creatures sometimes! Sadly though :!, it completely made sense to me!
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA

Online RDfella

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Re: Crank Balancing DIY
« Reply #32 on: 05.01. 2021 13:22 »
When the engine is apart, drill holes to make the crank over-balanced by a couple or so ounces. Then drill the opposite side until it is underbalanced by a similar amount. Tap that second batch of holes. You've then got a range of balance factors you can apply simply by fitting / removing screwed plugs from those latter holes. When you're working with experimental engines, where the balance factor is at best a guess, it's by far the easiest means of achieving a smooth engine. Been doing that for ages, though I think Richard too exception to the method when I mentioned it a while back. Maybe he misunderstood the expression 'window' that I used to describe access to those plugs. Of course, in most cases that 'window' already exists above the sump plate.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

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Re: Crank Balancing DIY
« Reply #33 on: 08.01. 2021 02:00 »
Well, I couldn't just let it be. I decided that by adding a few more drillings, I could lower the amount of weight I had to add to balance the crank. I did 3 more drillings and got the rotating weight down to 1190. With my recip weight, I settled on 58.33%. I think that will work pretty well for my style.
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA

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Re: Crank Balancing DIY
« Reply #34 on: 08.01. 2021 02:13 »
G'day Seabee.
I'm flattered.
The only problem with using an A7 head is the valve size. I ended up with a bit of a mish mash. SR valves but had to marry the A7SS collars to the SR collets and use SS springs. Using the SR gear the springs will bind, especially with a 357 cam.
Cheers
Howdy Musky,

I have completely restored the A7 (SS?) head with stock valves springs and keepers. What do I need to do to make it work with the 357 cam? I have a lot of time and $ invested in the head and really want to run the 357 cam. Is there a solution I can pursue?

Thanks in advance,

Seabee
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA

Online JulianS

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Re: Crank Balancing DIY
« Reply #35 on: 08.01. 2021 10:34 »
I have not used the A7SS head, however I used a 357 cam with an A10 iron head with standard A10 valves etc for many years and had no issues.

Currently using a 357 with A10 iron head, Road Rocket valves (not the big inlets), Road/Super Rocket spring seats and collets and Eddie Dow type top collars (from Ebor motorcycles) with WS type progressive springs. That works fine also. Why Road Rocket valves you may ask? Because I had a good set plus the bits to go with them from a wrecked (big crack) 67 1549 alloy head.

I assemble with a set of very weak springs first to makes sure of top collar to guide clearance and with proper springs check they are not coil bound.

Online muskrat

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Re: Crank Balancing DIY
« Reply #36 on: 08.01. 2021 12:28 »
G'day Seabee.
The 357 will be fine with an SS head and valve gear. I wanted the bigger SR valves in the Cafe's twin port SS head which is where I had to do some creative fitting.
Even my 51 A7 plunger has a 357 (with a 57 SS top end).
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

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Re: Crank Balancing DIY
« Reply #37 on: 08.01. 2021 13:29 »
Thanks Julian and Musky! What a relief..................
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA