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BIKELAND > FORUMS > DRAGBIKE ZONE.com > Thread: ZX-12R Wilmington Mile gearing for 200mph. NEW TOPIC NEW POLL POST REPLY
BA


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Posts: 1588
posted June 02, 2012 03:32 PM        Edited By: BA on 2 Jun 2012 22:49
ZX-12R Wilmington Mile gearing for 200mph.

Today was a very interesting day at the Wilmington Mile!! Winds usually in the 10-15mph range with gusts to 20 or slightly more. Sometimes it was a dead-on head-wind, other times it was at about your 2 o'clock. Made for some puckering moments up at 150+

I was hoping to get some opinions dropped in here about my gearing.
I have a 1287cc and was using 18/42 because it is just very slightly taller than a 17/40 when you look at a gearing chart. Oh, and my rear tire is a 190/55/17 at 42psi.
I have a 16, 17, 41, 44 and 46 sprockets to play with.

I went 189.8 on my only full run today and I missed 3rd gear when scooting back trying to get aero. I probably missed it twice there. Got some big new boots to blame for that too.
Now, with the wind, there was a lot going on at that speed on the big end of the track and I *thought* I had about 500-700RPM left.

So, I think I was in 6th gear, someone else said that they thought I might have been in 5th, and that I actually have too tall of a sprocket set on there.


What do you think?

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Shane661


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posted June 02, 2012 04:16 PM        Edited By: Shane661 on 2 Jun 2012 23:16
18/42 is way tall. 18/46 will pull 196 on a stock tire. A 190/55 is a very tall tire, but you should always measure the radius to see what the actual circumference is.

18/45 should do it, but 18/44 would be playing it safe. Extended revs and lower gearing would be a big help for you.

Shane

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oldkawboy


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Posts: 2123
posted June 02, 2012 07:17 PM        
Hey BA,

Good on you for running 190 in not so good conditions!!

As you know the 12's like to spin & ideally you should be at peak power going thru the traps. Like Shane said (and he knows) the 18/44 should keep you safe and from what you have with you, that's what I'd go with.

Good luck & keep us posted.
Dan

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Ken 12r


Novice Class
Posts: 85
posted June 03, 2012 02:43 AM        
Shane is right but I would try 18x46 first to see if it will pull the revs in top gear first in those sort of conditions then work from there.
18/46 could put you close with that tyre depending on other things like tyreslip.
____________
www.uklandspeedracingassociation.co.uk

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BA


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posted June 03, 2012 01:50 PM        
Thanks guys. I'll do a gear swap at the track this morning and see if I can "git r dun".

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BA


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posted June 03, 2012 02:26 PM        Edited By: BA on 4 Jun 2012 00:48
Funny - I forgot to hit 'Enter' after typing that above at about 6:30am this morning.

My buddies and I figured out that my missed 3rd and 4th shifts were partly due to the change in the angle of my foot from launching the bike, vs when I scoot my ass back to get tucked down.
I was pre-loading the shfter lever with my new big assed boots.

I put in the 44T rear sprocket this morning and with better shifting I was able to click off a 196.4, and then with a only about a 20 min wait, I was able to click off a 198.65768!! Pretty damned happy about that! I was hovering right around the bike's redline - per the factory gauge, which I think the limiter is a little into the redline. I probably could have used +1T more rear gear..

There was still headwinds this morning, and that turned into changing headwind & the same two o'clock winds as we had yesterday.. Even in early morning at 8:30am we had 5-12mph winds.
The afternoon brought some higher gusts with it,.....but not quite as bad as yesterday but still enough to bring your mph down.

I was so close to 200 that I re-strapped the front of the bike to close up the last finger width of space between my fender and the bottem of the ram air scoop,.....took off my license plate and got back in line for another attempt......BAM...the bike wouldn't start and it's my turn to Go!.
I had to get a push start from the ECTA line guys, and they let another guy go ahead,...then they let me get to the line again, engine now running.. That was nice. I ran a 197.3 but spun twice in first gear. The first one I eased out, the second one I stayed in it.

Getting ready for my last pass, I lowered the rear of the bike it's last 1" - 1.5" or so, to where the rear of the fairing would certainly scrape on a hard launch. I let the bike cool down a bit and when I was getting on it to go run again - that was at 3:15 when they closed everything down.

All in all, I had a good weekend.

Link to speed-slip:
http://www.media-swap.com/19865768.jpg




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Shane661


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posted June 03, 2012 02:34 PM        
Your bike had about 500 rpm left it it, say roughly 7.5 mph. 1 tooth more would have put you right around 201 on the limiter, as suspected. If there had been less wind, I think the 18/44 would have been perfect for you.

Congrats on the 198, and you are sure to see 200 in the future!

Shane

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BA


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posted June 03, 2012 03:01 PM        Edited By: BA on 4 Jun 2012 00:32
Thanks Shane. You were instrumental in helping me to get ready and it was good meeting you and Rachel. (and everyone else of course.)

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Shane661


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posted June 03, 2012 03:04 PM        
Good to meet you, and awesome job! That bike must run great to run those #'s in that wind! And great riding, no doubt...

Shane

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2000redrocket


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posted June 03, 2012 06:05 PM        
shane do not forget it is also the red
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oldkawboy


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Posts: 2123
posted June 04, 2012 07:30 PM        
Congratulations Alan, you REALLY done well!

Shane, I gotta agree, he rode the wheels off that 12 but then again BA was always a great dragracer.

Hope you make the July event.

Dan

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