wannabe
Pro
Posts: 1931
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posted February 17, 2003 08:11 PM
 Edited By: wannabe on 17 Feb 2003 20:13
ZX-12 Shift point
OK, I just got back from the track. I am so confused. I got so much advice from everyone, but nobody seemed to agree on how to do anything. But, here's the one that confused me the most:
One of the guys there told me that I was shifting at too high of an RPM. I've been shifting at 11K. He said that I should shift to maximize the torque. I thought that you were supposed to shift to maximize HP. (See my baseline dyno run.) If I'm right, I'm shifting at the right time. If he's right, I should be shifting somewhere between 9500 and 10,000 rpm. I tried the shorter shifting and ran a tenth slower with about 10 mph less as well.
Who is right? Did I just mess up the runs where I short shifted? You guys racing the 12, what rpm do you shift at?
I don't know if it matters, but I was running with a 17/48 gearing. I'm still bogging. I'm gonna go down to the 16 front next time.
  
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fastestr1
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posted February 17, 2003 08:43 PM
I shift at 11,500 with 16/49 gears, a 1361 you might want to shift at lower RPM's.
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Black 02, 8.99 @ 161.95 motor on NOS
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kawachan
Pro
Posts: 1031
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posted February 17, 2003 09:17 PM
Rickey G told me to shift "right' before red line. Matter of fact, he put a piece of tape on my tach and said "shift here!". Tape still there and I ain't taking it off.............
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Cowboy
Pro
Posts: 1061
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posted February 17, 2003 09:30 PM
11,400 and if you went 1/10th slower short shifting why the heck you asking us???????
What do you mean you are bogging still???Your rev limiter is your launch limiter.17/51 seems to work the best for me and play with tire pressure until you get rid of the bog.
ps.I don't use bars on street bikes anymore.Slows you down too much
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RedBull
Expert Class
Posts: 406
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posted February 17, 2003 10:00 PM
Edited By: RedBull on 17 Feb 2003 22:02
With a bar & a slick, you must be feeling better...
It seems that you would want to be at peak torque in the next gear...
So look at what your bike is at after you shift.
I know that when I want to slow my 11 down, I shift it short,
& it seems like it works for you too Aris...
According to your seat of the pants-o-meter, You should know when to shift.
What gear are you going through at the top ?
Red, *<(:{)-
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wannabe
Pro
Posts: 1931
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posted February 17, 2003 10:22 PM
Thanks, guys. I knew I was right. I just needed a second opinion. I would have made a bunch more runs short shifting before I proved it to myself. I'm so new that I'm stll second guessing everything I do.
Cowboy, are you saying that I should be launching at redline? 17/51, huh? That's the same as 16/48, right? (I have a 16 toother in my garage right now.) And, what do you mean about playing with tire pressure until the bogging goes away? If I bog, increase or decrease tire pressure?
Red, yeah, I am totally comfortable with the bars now. I had to take it easy in the beginning since this was my first day back since my last 'get-off' at the strip. As for the gear, if I remember correctly, right now I'm shifting into 4th somewhere around the 1000-foot marker. Hopefully, the 16 front will get me into 5th. That MT tire is taller than the stocker.
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fastestr1
Expert Class
Posts: 300
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posted February 17, 2003 11:12 PM
If you are bogging then increase the tire presure 5 psi at a time so it spins alittle and the rpm's stay up.
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Black 02, 8.99 @ 161.95 motor on NOS
Put one knee down for the curves and both knees down for GOD
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harryzx-12
Needs a job
Posts: 3643
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posted February 18, 2003 06:38 AM
I shift at almost 12,000 on my tach which is just before the rev limiter (the tach is not completely accurate) . I need all the HP I have. The only time I short shift is if I wheelie.
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Cowboy
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posted February 18, 2003 07:22 AM
When i say play with tire pressure I mean add 1 or maybe 2 lbs at a time.Definately not 5 lbs.5 LBS MAKES A HUGE DIFFERENCE WITH A SLICK.But yes,you in a perfect world you want about 2 revolutions of the tire.When I had bars & slick on a stock 12 I launched at redline with 17/51.I don't really like the idea of the 16 tooth on the front.Best times were 9.20 with air shifter.(stock clutch basket back then too)lol
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wannabe
Pro
Posts: 1931
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posted February 18, 2003 07:51 AM
Please excuse my ignorance here, but what is the drawback to running the 16/48 vs. the 17/51?
Wow, I didn't know about wanting to spin the tire two revolutions. I need to work on that. I guess reading the track conditions just comes with time and experience?
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your car is slow
Needs a job
Fuck Nitrous...Got Boost?
Posts: 4089
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posted February 18, 2003 08:59 AM
17/51 id think would provide better "leverage" for the motor while being mathmatically the same "ratio"
Think about how much easier it was on your old 10speed (the one with the multiple front sprockets) when the chain was on the two largest sprockets in the front and rear vs when its on the lil front..and the big rear.
Plus the chain doesnt travel in nearly as tight a circle with the 17t as it does the 16t (youd really be suprised at the difference..I was)
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Cowboy
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posted February 18, 2003 09:16 AM
exactly
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RAC4IT
Needs a job
Bergie
Posts: 3009
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posted February 18, 2003 12:23 PM
Wind that engine until just before the limiter; N/A. If you're spraying, give yourself a little safety room, 500 before the limiter is good. If you short-shift a 12 you lose crazy MPH, and some ET. A stock 12 with a pipe ~169rwhp will trap 149mph if you shift it right!
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krexken
Zone Head
Posts: 732
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posted February 18, 2003 03:01 PM
What rpm are you launching at, WB? That would be one of the first things I'd experiment with. I'd keep upping it to the bog went away, then perhaps lower tire pressure again and keep upping the launch rpm to get the maximum et.
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MadMike
Moderator
FEAR THE BLACK FLAG!!!!!!!!
Posts: 6579
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posted February 18, 2003 04:55 PM
I run 17/51 on my bike
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wannabe
Pro
Posts: 1931
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posted February 19, 2003 11:25 AM
One last question for you guys:
Is 120 links on the chain enough to fit the 17/51? The stock is 116, and I have just enough room for a 17/48. Will 4 more links be enough to fit throw the 51 on the rear?
I'm gonna go ahead and take your advice and give the 17/51 a try. I just want to make sure that I order enough links on the chain.
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"There are only three sports: bullfighting, motor racing, and mountaineering; the rest are just games." - Ernest Hemingway
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your car is slow
Needs a job
Fuck Nitrous...Got Boost?
Posts: 4089
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posted February 19, 2003 11:28 AM
Think you have to add at least a link for every new tooth you put on the rear dontcha?
Id add more than 4 if I were you....would be nice to have an extra inch of wheelbase no?
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Cowboy
Pro
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posted February 19, 2003 03:40 PM
You answered your own question."just enough room for a 17/48"
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wannabe
Pro
Posts: 1931
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posted February 19, 2003 04:09 PM
Cowboy, I know that the 17/51 is not going to fit in the stock (116) chain length. I was just trying to figure out whether or not I could get away with ordering the 120 link. I didn't know about the 1 link per tooth rule. I decided to just play it safe and order the 138 link chain along with the 51-toother.
But, in the meantime, I'm gonna run the 16/48 until the chain and sprocket show up.
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"There are only three sports: bullfighting, motor racing, and mountaineering; the rest are just games." - Ernest Hemingway
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fastestr1
Expert Class
Posts: 300
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posted February 19, 2003 04:12 PM
Why are you changing from a 16/48 to a 17/51?
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Black 02, 8.99 @ 161.95 motor on NOS
Put one knee down for the curves and both knees down for GOD
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wannabe
Pro
Posts: 1931
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posted February 19, 2003 04:14 PM
quote:
17/51 id think would provide better "leverage" for the motor while being mathmatically the same "ratio"
Think about how much easier it was on your old 10speed (the one with the multiple front sprockets) when the chain was on the two largest sprockets in the front and rear vs when its on the lil front..and the big rear.
Plus the chain doesnt travel in nearly as tight a circle with the 17t as it does the 16t (youd really be suprised at the difference..I was)
I'm changing because they talked me into it. See above. Honestly, I was really on the fence about running the 16-toother to begin with. The boys just helped steer me. 
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"There are only three sports: bullfighting, motor racing, and mountaineering; the rest are just games." - Ernest Hemingway
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Cowboy
Pro
Posts: 1061
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posted February 19, 2003 07:21 PM
Now you will be able to tell us if you feel a difference BETWEEN THE 16 AND 17 FRONT.You made the right choice to go with more than 120 links because now you can run about 123 to get you some more wheelbase.
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justoyz2
Zone Head
Justoyz Racing
Posts: 858
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posted February 20, 2003 10:15 AM
WanaB,
gearing is tricky, what might work for you might not work for the next rider and vis versa. I run better with 16/49, then anyother combinations I have tried.
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wannabe
Pro
Posts: 1931
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posted February 20, 2003 10:22 AM
justoyz, are you seeing any chain life issues with the 16-toother in the front?
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"There are only three sports: bullfighting, motor racing, and mountaineering; the rest are just games." - Ernest Hemingway
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RAC4IT
Needs a job
Bergie
Posts: 3009
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posted February 20, 2003 02:49 PM
I do. 16T wears a chain out a lot quicker.
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