entropy
Moderator
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posted April 10, 2002 04:00 AM
crank balancing?????
who knows what's really involved? I have never seen it done and am more than just curious.
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ROCKET J
Zone Head
Goes to water over a dummy!!!
Posts: 602
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posted April 10, 2002 04:39 AM
 Edited By: ROCKET J on 10 Apr 2002 05:40
Try these guys...
Hope this helps:
http://www.faliconcranks.com
Rocket
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ZXtra
Expert Class
Posts: 490
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posted April 11, 2002 01:05 AM
Re: crank balancing
entropy...It's been a few years, but I used to do it for a living.
All moving parts are dissassembled.
Each end of the rod is weighed separately, then all ends are ground to match the lightest ones.
Same with the pistons. All are machined to match the lightest one.
Piston rings and rod bearings are weighed.
All the weights are recorded and added up to get a weight that is duplicated by some bob weights that are bolted to the crank pin journals.
The assembly is then spun on a balancer that senses unbalance at each end of the crankshaft separately.
There is a strobe light on the balancer that tells the operator where the heavy spot is.
You then have to remove weight from the crankshaft by drilling or grinding at the heavy spot.
If thats not possible, then you weld weight 180 degrees from that on the light side.
After this is done and the assembly spins smoothly, you add fly wheels and clutch parts individually and balance each one in turn so that everything runs smooth after assembly.
I hope this helps. -ZXtra
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psycho1122
Pro
Posts: 1608
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posted April 11, 2002 07:21 AM
KAWASAKI Quote....
If any of you have received the "Silver 12R Story Book", Here is a qoute out of it,
"Production Tollerances of the ZX12R's pistons and other reciprocating parts so close that conventional BLUEPRINTING techniques are NOT NECESSARY.
Now that I have been inside this engine and have checked tollerances, I an see how true this is!!!
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frEEk
Administrator
ummm... yeah
Posts: 9660
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posted April 11, 2002 08:07 AM
thats good to hear (about how tight our engiens are), but seeing as how a number of members seem to have experienced good results from ballancing, i wonder just how true that is? i gotta say tho, i don't see why a manufacturer, especially one that makes high performance bikes, can't blueprint an engine when they manufacture it? we pay quite a bit for the bikes to begin with, and they much check balance etc when they build the engine anyway, so why not take a little more time & make it more accurate? i can't imagine it would cost more than a few hundred bux more. or am i completely unbalanced? 
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entropy
Moderator
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posted April 11, 2002 11:47 PM
Edited By: entropy on 12 Apr 2002 10:29
thx Rocket and ZXtra,
Very interesting process. Is this a process that is done routinely at many crank shops or is it considered an "exotic" process only done for hi $ race vehicles at a few places in all of US.
Freek, what made you quit balancing stuff and go to IS?
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frEEk
Administrator
ummm... yeah
Posts: 9660
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posted April 12, 2002 07:24 AM
i think u mean ZXtra no?
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EastBayDave
Needs a job
Posts: 2245
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posted April 12, 2002 08:34 AM
ZXtra: very cool explanation...thank you! 
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02' ZRX1200
00' ZX12R sold
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ZRXDean
Needs a job
Posts: 2225
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posted April 12, 2002 08:59 AM
I think ZXtra is talking about balancing automotive rotating assemblies. I sent my crank to Falicon last winter for balancing, and talked to the foreman about how they do it. They don't account for the rods or pistons, they just balance the crank itself. They spin in and shave it. That's why it was only $150 and takes one day.
Dean
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dougmeyer
Needs a job
moderated
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posted April 12, 2002 10:19 AM
A couple of things here,
The tolerances in stock 12 engine are as good as most automotive "speed shops" ever did. It is only when you put in modified or new parts that re-balanceing can be needed.
The reason that a ZX-12 crank doesn't need to be spun with bob weights is becasue it is a 180 deg. or "flat" crank. That is, the crank itself is in "primary balance"- it will spin freely in balance without any rods and pistons attached. The rod throws are opposite from each other and cancel out. On a crank with offset throws (like every 90 deg.) you need the weight of the rotating percentage of the rod/piston assy. on the crank to get it in balance. This is simulated with the bob weights that match the actual weights of the rod and piston (but not the TOTAL weight, just the percenatge of the weight that rotates). When you balance a flat crank you spin the crank, get it in balance, then weigh each piston and rod assy and match them or at least create two pair. As long as one assembly of a pair is on one throw and one on the opposite (one up-one down), the assy remains in balance.
Doug
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eric00zx12r
Novice Class
Posts: 97
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posted April 12, 2002 10:39 AM
Just tell me where else you can go and get the kind of experties we have here !!!
Love this place.
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Eric
00ZX-12R
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ZXtra
Expert Class
Posts: 490
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posted April 12, 2002 06:42 PM
quote:
thx Rocket and ZXtra,
Is this a process that is done routinely at many crank shops or is it considered an "exotic" process only done for hi $ race vehicles at a few places in all of US.
entropy...This process is an extra cost option when building an stock engine. I don't know of any shops that would routinely throw it in. But for any hi perf applications most peolple just do it. -ZXtra
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