Gearing on zx 1200r

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Greg Watters
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Re: Gearing on zx 1200r

Post by Greg Watters » Tue Apr 17, 2012 9:23 pm

in my experiance C of G is in more than one plane , too low is as bad as too high , too far to the back and you have a pendulum , too far front and its no use
And have you ever tried to throw a dart backward ...
I took a very well mannered bike that was the fastest outright at Bubs 2010 and made it into a poor handling beast , moving the weight down and extending the 35mm swingarm more :evil: ,

And weight near the singarm pivot could be considered semi sprung

kermitracing
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Re: Gearing on zx 1200r

Post by kermitracing » Wed Apr 18, 2012 5:32 pm

Hi Stayt'ie and Greg, Thanks for the tip on the balance thing between both front and back wheels. At the moment it handles like chopper with the 20 kg. in the swingarm so I will bring along some front forks straps to rachet them front down a tad. The 12,s in their natural unmolested state have an elevated back end so they tip easier into corners so when you muck a round with the geometry the handling charateristics go out the window. Don't know why, but they seem to be a much maglined bike, always seem to run bridesmaid to those ugly busa's (no disrespect to busa riders). I know the busa's are slipprer and that will be next years project to make the kwaka shaped like a banna so i can slid on past them.
Cheers Paul

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RGV
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Re: Gearing on zx 1200r

Post by RGV » Thu Apr 19, 2012 1:50 am

Dont know if you have seen this before. Why Bussas are quicker. Its not all HP.

http://www.sportrider.com/tech/146_0106 ... to_07.html

Last Minute Racing "its a 2-stroke ya twit - Its supposed to smoke"
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Stayt`ie
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Re: Gearing on zx 1200r

Post by Stayt`ie » Thu Apr 19, 2012 5:19 pm

i have read that, and similar stuff before, and find it a little puzzleing, as on the dragstrip, a 12 (in standard form) will topend Busa`s of the same era, :?
despite what you read in the media, the 12 actually has a smaller frontal area than the Busa,, however the tail area is what restricts them aerodynamicaly :roll: ,, blind freddie can see how "enclosing" the Busa rear bodywork is,,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

momec3
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Re: Gearing on zx 1200r

Post by momec3 » Sun Apr 22, 2012 12:04 pm

Greg,

An interesting observation on C of G. Made me think about why? What came to me was the thing we used to do as kids when we had the front wheel off the pushie.

Hold each end of the axle and spin the sucker. Even at those slow speeds the gyroscopic effect was so strong.
Must be enormous on both ends of a bike at speed.

Is the axle centreline where the C of G needs to be aimed on a bike for high speed stability (straight line)??
Is the leverage effect of lowering your C of G like holding the pushie front wheel instead of the axle but say the headstem of a set of forks and trying the same exercise; much more dificult to control the motion.

I'm most likely stating the obvious to you bike guys but the charicteristics are so opposite to building a stable car it made me give it so thought.

Chris
Chris

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RGV
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Re: Gearing on zx 1200r

Post by RGV » Sun Apr 22, 2012 1:28 pm

It seems the C of G can be too low. Heres a pic of a Honda GP bike that didnt work, fuel tank at the bottom.

Image

Last Minute Racing "its a 2-stroke ya twit - Its supposed to smoke"
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2010 MPS/G 250 118 MPH:)
2011 Washed Out:(
2012 Washed Out:(
2013 MPS/G 250 131 MPH (RECORD):)
2014 MPS/G 250 140 MPH (RECORD):)
2015 MPS/F 250 DNF:(

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Greg Watters
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Re: Gearing on zx 1200r

Post by Greg Watters » Sun Apr 22, 2012 8:14 pm

RGV Any details about the bike ,??

Chris , not sure why , but my handling turned bad and when i talked to a guy in the US , he had similar problems , to the point the track marshal had called rider down, but he did not quite crash, maybe the gyroscope saved him ;)
but his only change had been similar to mine , decided it would be better to make the weight sprung and low
put it back to previous positions and all was well again , mine is not realy sprung just tried to make use of some empty space
this is my new weight box , and will be getting some of the lower section removed
Image

momec3
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Re: Gearing on zx 1200r

Post by momec3 » Tue Apr 24, 2012 6:37 pm

RGV. Always think if it looks right it is right.

That thing looks all wrong but at least it would be good at roasting nuts. :lol: :lol: :lol:

Chris
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JonB
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Re: Gearing on zx 1200r

Post by JonB » Wed Apr 25, 2012 8:04 am

Honda ran that bike in 1984, ridden by Freddie Spencer.
Freddie hated it as the COG was too low with a full tank to get decent weight transfer under accelaration and braking.
Mechanics hated it as they had to pull the exhaust to do anything at all on the engine.

Cheers
jon
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Greg Watters
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Re: Gearing on zx 1200r

Post by Greg Watters » Wed Apr 25, 2012 8:15 am

:D thanks Jon

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