Balanced Flywheels
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Cruiser
Joined: Aug 2009
Posts: 115
Likes: 1
From: Portland, Oregon
Balanced Flywheels
This might be a subject that has been discussed here but I tried searching and could not find anything. S&S sells balanced flywheel assemblies for dynas and I was wondering how effective this might be in controlling the vibration in dyna engines. I am guessing not much due to the design of the Harley motor. Is there anybody here that has balanced flywheel assemblies and can share their experience? Is this a worthwhile investment? They are quite pricey.
Tourer
Joined: Sep 2009
Posts: 467
Likes: 0
From: Lancs, England
The whole caboodle would have to be balanced - crank, flywheel, pistons, clutch etc to make it worthwhile. Why do people bitch about the Harley vibes anyway? The vibes are what make it a Harley, if you don't like them go buy a Jap cruiser - simple. 
Just a little note on vibes, I find my bike vibes more with certain makes of fuel - here in the UK it seems to get more vibey with BP who use a % age of bio fuel mixed in, vibes like monkey on acid with that stuff.
Seems to be a Europe thing now, France have just passed a law recently that they have to mark the pumps if there's Bio fuel in the mix - we're not so lucky here so we get all the crap
.
Derv
Just a little note on vibes, I find my bike vibes more with certain makes of fuel - here in the UK it seems to get more vibey with BP who use a % age of bio fuel mixed in, vibes like monkey on acid with that stuff.
Seems to be a Europe thing now, France have just passed a law recently that they have to mark the pumps if there's Bio fuel in the mix - we're not so lucky here so we get all the crap
.
Derv
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Outstanding HDF Member
Joined: Sep 2007
Posts: 3,352
Likes: 4
From: Augusta, GA
The whole caboodle would have to be balanced - crank, flywheel, pistons, clutch etc to make it worthwhile. Why do people bitch about the Harley vibes anyway? The vibes are what make it a Harley, if you don't like them go buy a Jap cruiser - simple.
Just a little note on vibes, I find my bike vibes more with certain makes of fuel - here in the UK it seems to get more vibey with BP who use a % age of bio fuel mixed in, vibes like monkey on acid with that stuff.
Seems to be a Europe thing now, France have just passed a law recently that they have to mark the pumps if there's Bio fuel in the mix - we're not so lucky here so we get all the crap
.
Derv
Just a little note on vibes, I find my bike vibes more with certain makes of fuel - here in the UK it seems to get more vibey with BP who use a % age of bio fuel mixed in, vibes like monkey on acid with that stuff.
Seems to be a Europe thing now, France have just passed a law recently that they have to mark the pumps if there's Bio fuel in the mix - we're not so lucky here so we get all the crap
.
Derv
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I haven't purchased a balanced flywheel assembly from
S & S (because we balance every engine we rebuild and the flywheels are re-used) but I have purchased the items to rebuild an S & S engine. I can assure you that if you order a "balanced" assembly from them it will either include the entire reciprocating/rotating mass or you will have sent them the weight of your pistons, rings, wrist pins, and snap rings and that weight will have been added to the connecting rods and bearings before any balancing is done.
Now, if you've done a big bore kit as thedonthere is planning to do and myself have done, the original balance is off by a few percent because the weight of the new pistons, rings, wrist pins, and snap rings are not identical to the weight of the take off parts. There is a 4% window, +/- 2% when balancing is done.
~~~~~~~~~~~~~~~~~~~
To the OP, if you are having vibration issues and the dealer says you don't have a problem, find another dealer or mechanic and tell them what it's doing that you think it shouldn't be doing. Someone out there will take the time to examine your problem and explain what they think you are experiencing without the "it's fine" brush off.
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Outstanding HDF Member
Joined: Sep 2007
Posts: 3,352
Likes: 4
From: Augusta, GA
I'm going to revise my comment above.......
I mostly deal with cast flywheels in the evo and s&s engines and seldom work on twin cams. As an example, I am currently rebuilding three(3) panhead engines, two (2) shovelhead engines and, one (1) S&S engine (96 cu) and realized I just don't work on that many twinkies so..... Today I was cleaning parts and looking at assembling a twin cam 88 I an building and realized when I ordered the "crank assembly" that no one asked me for the weight of the pistons, rings, wrist pins and hog rings.......
The twinkies crank assembly is a forged unit and there are no drill holes where the crank was balanced. The older units are cast and have to be balanced the "old school" way but these newer engines are not cast and they are not balanced in the way the older ones are.
In retrospect, I would say that one of the primary reasons some of these engines create so much vibration is directly because they are not balanced and purchasing a "balanced" flywheel assembly could result in a very much smoother engine and motorcycle.
Good luck with your decision to purchase or not and let me know, if you do decide to go the long way, what the result is.
I mostly deal with cast flywheels in the evo and s&s engines and seldom work on twin cams. As an example, I am currently rebuilding three(3) panhead engines, two (2) shovelhead engines and, one (1) S&S engine (96 cu) and realized I just don't work on that many twinkies so..... Today I was cleaning parts and looking at assembling a twin cam 88 I an building and realized when I ordered the "crank assembly" that no one asked me for the weight of the pistons, rings, wrist pins and hog rings.......
The twinkies crank assembly is a forged unit and there are no drill holes where the crank was balanced. The older units are cast and have to be balanced the "old school" way but these newer engines are not cast and they are not balanced in the way the older ones are.
In retrospect, I would say that one of the primary reasons some of these engines create so much vibration is directly because they are not balanced and purchasing a "balanced" flywheel assembly could result in a very much smoother engine and motorcycle.
Good luck with your decision to purchase or not and let me know, if you do decide to go the long way, what the result is.