Author Topic: Crank Balancing  (Read 4538 times)

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Offline don46

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Crank Balancing
« on: September 19, 2007, 04:22:12 AM »
I always like to learn new things, and as such Crank balancing has been on my mind, or more to the point how too balance a crank. Truing is no problem, or installing a new rod, but the balance part has me thinking, does anybody know how they do it? In my mind I would seperate the crank, remove the rod, piston, pin, circlips, lower rod bearing and washers, weigh them, re-assemble the crank with only the pin and attach a equal weight to the rod pin and then static balance it using a set of precision ways with knife edge wheels. This may not be the right approach but it seems to me that I read somewhere once that this was how it was done, any comments.
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Offline doordie

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Re: Crank Balancing
« Reply #1 on: September 19, 2007, 05:20:53 AM »
This is mine crank made by my german friend Mike Melde. 8-)

My bike runs awesome with that crank,can not exactly explain why though.
Smooth out powerband and do not vibrate as normal with a big single
piston engine.

Tungsten is used to balancing against piston/rod. :wink:
Iceroad champion 2006,still 2007,even 2008 without a single race!

Offline kaw rider

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Re: Crank Balancing
« Reply #2 on: September 19, 2007, 07:55:15 AM »
Doordie
has all the goodies in his motors.

Offline Platypus

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Re: Crank Balancing
« Reply #3 on: September 19, 2007, 09:31:46 AM »
How much for one of those cranks doordie?  I would love to reduce the vibration!

Offline KXcam22

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Re: Crank Balancing
« Reply #4 on: September 19, 2007, 05:34:04 PM »
Don,
  I'm no balacing pro but I think the idea is to balance the crank so the entire reciprocating mass, piston & rod inlcuded is in balance. Cam.

Offline don46

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Re: Crank Balancing
« Reply #5 on: September 20, 2007, 03:21:58 AM »
Cam,

I know nothing about crank balancing, I thought I would open the discussion so perhaps somebody that did know would enlighten me. Looking at Doordie's crank, it appears alot of metal was removed. Also I would think it will make a difference as to what piston you were to run, a Wiesco may be lighter than a stocker, so if balanced with a stocker you would want to stay with that same type.

Maybe somebody that is in the know will chime in.
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Offline Platypus

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Re: Crank Balancing
« Reply #6 on: September 20, 2007, 05:43:57 AM »
I just found this by doing some google searches for 2 stroke crank balancing:

Can a single cylinder crankshaft be balanced? Does it help?
A single cylinder crank is always unbalanced. The balancing operation we
perform moves that unbalance (vibration) that is either higer or lower than
your engine's RPM operating range. We accomplish this by removing or adding
weight to the crank in a location that our balancing equipment has told us
to do so. Balancing or "moving the unbalance" really helps a single cylinder
crank, especially if it is to be used at sustained high speeds.

Here is a company that makes equipment for balancing cranks:

http://www.cwtindustries.com/crankshaft%20balancer.htm

So they basically try to hide the imbalance in an RPM range that is rarely used.  For someone like me that is all over the board when I'm racing because I get tired or can't deal well with the terrain I don't think it's going to make that big of a difference.  Take someone with consistency and I think it would make for a much smoother ride overall.

Offline doordie

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Re: Crank Balancing
« Reply #7 on: September 20, 2007, 06:16:18 AM »
Here is a another pic of Mike Meldes works on a twin. 8-)

It?s something with the power stays longer and will not
"flatten out" in high rpm range... :|
It will not stress crank "tap" as flywheel weights does and more centred of engine.
In tarmac racing it?s make a huge different because 100% grip. :evil:

Platypus,sorry "one of kind" :cry:
« Last Edit: September 20, 2007, 06:18:11 AM by doordie »
Iceroad champion 2006,still 2007,even 2008 without a single race!

Desert Panther

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Re: Crank Balancing
« Reply #8 on: September 20, 2007, 06:32:07 PM »
Here is a another pic of Mike Meldes works on a twin. 8-)

It?s something with the power stays longer and will not
"flatten out" in high rpm range... :|
It will not stress crank "tap" as flywheel weights does and more centred of engine.
In tarmac racing it?s make a huge different because 100% grip. :evil:

Platypus,sorry "one of kind" :cry:

What kind of engine is that?!?! It has twin cranks?  :-o     although I think Suzuki made a 500cc 4 cylinder  2 stroke that had a setup like that, called the RG500 Gama?

Offline kaw rider

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Re: Crank Balancing
« Reply #9 on: September 21, 2007, 08:16:54 AM »
Doordie
how much weight was added to your crank.