Gearing on zx 1200r

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kermitracing
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Gearing on zx 1200r

Post by kermitracing » Tue Apr 10, 2012 11:46 pm

Hi all, Not having raced on salt before and having only drag racing experience back in the late 70's I need some advice on gearing for the salt. Through much deliberating and a suitcase full of bright unused rear sprokets I have settled on a 41 rear and 17 front. The bike developes around 200 RWP when I am spraying nitrous but I also need to get up to 9000 rpm on gas with 160 rwp before hitting the button. So if anyone could give me some advice based on their experiences with gearing, especially a zx1200r would be greatly appreciated.
Cheers Paul

Stayt`ie
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Re: Gearing on zx 1200r

Post by Stayt`ie » Sat Apr 14, 2012 5:23 pm

what shot of nos you planning on using, :?: , 200hp, 40 shot, :?:
First Australian to ride a motorcycle over 200mph at Bonneville,,,

kermitracing
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Re: Gearing on zx 1200r

Post by kermitracing » Sat Apr 14, 2012 11:32 pm

Hi Stayfie,
Thanks for the question.
Currently on a 40 shot with progressive controller. Want to try and keep the wheel spin down and the top speed up hence the taller gearing. I have run it up on the dyno on a 44 tooth rear but its still a bit savage when the power comes on. I know there is splipage on salt and I am not even sure if my 2.5lb bottle will last the distance through the timing area but i figure this is all a learning exercise, Iam not out to break records first time out on the lake.
Cheers Paul

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JonB
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Re: Gearing on zx 1200r

Post by JonB » Sun Apr 15, 2012 6:05 am

Hi Paul

Wouldn't you just gear for the highest speed you think you can pull at max hp in top gear with a bit for slip?

Cheers
jon
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Stayt`ie
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Re: Gearing on zx 1200r

Post by Stayt`ie » Sun Apr 15, 2012 9:06 am

most of the fellas running modern sportsbikes these days work on -6% slippage for faired on reasonable to good salt, -8% for naked,, obversley as your aero package improves those % will decrease,,,
you will not have a problem pulling up to 9000rpm in 6th on the standard motor, however, depending on which gearing you choose, ya gunna have to pay close attention to working the throttle, :wink: ,,
are you planning on using a air shift :?: , the jurys out on this, i dont, as i recon thay promote wheelspin,,
from 170 to 210mph the average over one mile is approx 19 seconds, at 200 its 18 secs, 215 its 17 secs, i would advise choosing the 3-4 mile as your top speed mile, three mile run up should be plenty to get you there and settle the bike, work at this, if you dont feel its enough ya still have the option of the 4-5, (you dont have to top speed thru all the timed miles),,how long will your bottle last :?: , thats your call,,
200rwhp on a ZX12 equates to mid 2teens, 227-6%= 213,, my sums tell me final ratio in the low 2.3 range, 18/41 or 19/44,,
with that rwhp ya gunna need ballast, if you dont the thing will slip slide everywhere, how much ballast :?: , as much as you can get on there, keeping in mind wheel bias, dont go beyond 60/40, (too much on the frount and the back wants to come around, same too much on the back and it wants to pass the frount :twisted: ), keep the weight low,,
disclaimer:- none of the above will work for a Hayabusa, :mrgreen: ,, "Go the Kawasaki`s" :lol: :lol:
First Australian to ride a motorcycle over 200mph at Bonneville,,,

hawkwind
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Re: Gearing on zx 1200r

Post by hawkwind » Sun Apr 15, 2012 11:59 am

Paul when I ran nitrous on the BUSA back in 94 /95 I tried it with both pulsed & non pulesd ...in 94 I ran a 2.5 lb bottle with a range of shots from 40 to 100 non pulsed it comes on very hard that way but is a hoot rooster tail of salt and mucho tyre spin..... with a40 I did not increase my top end in fact it went backwards no traction same for a 60 as well ... just for fun I even tried a 100 ... club animal said it was the best site & sound he had heard ..I hit it just before the 3 mile marker fishtailed for a half mile and thought I lost the clutch but it turned out to be wheel spin .. this got me through the 4 mile at a touch over 200mph ..... the next year I graffed 2 x 10 lb bottles and a modified controller I purchaed from joe amo from the us ( I still have it ) that year I had lots of ignition problems and did not set a good time .... gave up the nitrous after that and went turbo ... I still have all the nitrous stuff and may again play with it .
Gearing ... I just used I tooth larger on the countershaft and a couple smaller at the rear ...I have a great gear calc somewhere will give a link when I find it

gary #282
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Greg Watters
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Re: Gearing on zx 1200r

Post by Greg Watters » Sun Apr 15, 2012 3:30 pm

Gary wasn't that 04-05 ? :wink:

As long as your not undergeared your top speed will be fairly close to its potential

Last yr in the US Jim and Kim had been running Jims std busa with near optimal gearing ~187mph , then i put on a wheel tire combo i wanted to test and went from a 38 rear sprocket to a 30 (all we had that fitted that wheel) and ran 184 in 4th gear , couldn't quite pull 5th .

From this experiance i would suggest overgearing , see what it will pull then optimise your gearing for the next run

How long does your 2.5 lb last, have you tested to see how long it sprays for before chilling the bottle and dropping pressure

Probably going to have to treat it like a 2 mile dash , (as we start at 1) hit the button around the 2.5 and see if it lasts to the 3.25 for a 1/4 mile speed
as the bottle will probably not last long enough to get up to speed and hold it for a mile

kermitracing
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Re: Gearing on zx 1200r

Post by kermitracing » Sun Apr 15, 2012 6:38 pm

Hi All Thanks for the input.
I will work on trialing a 41 and a 38 as I have 2 x 2.5lb. bottles. It sounds petty exciting wheeling for half a mile hunting for traction. I have filled my swingarm with 20 kg of lead shot and lowered the bike by 50mm.I am hoping the bottle will last 18 to 20 secs and this is about what i need to get through the timed area. I took the bike up to the West Coast of Tas. found a very quite streach of straight road and hit the button at 9000 in fifth. I thought for a sec. nothing was happening and then the front end did a little jump and everything got incrediably blurry, breifly saw 300 in fifth before the road ranout, was an awesome experience!I know we are suppossed to be responsible at our age but sometimes calculated risks are worth it!!!
Thanks again for all the comments.
Cheers Paul

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Re: Gearing on zx 1200r

Post by hawkwind » Mon Apr 16, 2012 8:18 am

yes Greg only 10 years out hahaha must be oldtimers hey ?
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Greg Watters
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Re: Gearing on zx 1200r

Post by Greg Watters » Mon Apr 16, 2012 9:45 am

:lol:


Kermit, 20kg may not be enough , i run 120+kg

Stayt`ie
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Re: Gearing on zx 1200r

Post by Stayt`ie » Mon Apr 16, 2012 7:01 pm

what Greg said, and more, :lol:
quick sums off the top of my head, on a ZX12 with standard body work at 213mph, you will be fighting a 400+`lbs wall of air,, :wink: :)
i have had "no" experience with nos,,, i feel that your major traction issues are going to be when you introduce the gas, IMAO, i figger any amount of ballast isnt going to help much "at that point",, after which, it will be a matter of settling the bike and working it up to speed, then, ballast will be your friend,, 8) ,, but, do you have enough gas?, yep, it aint easy, :D ,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

kermitracing
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Re: Gearing on zx 1200r

Post by kermitracing » Tue Apr 17, 2012 6:11 pm

Hi Greg, Stayt'ie, Hawkwind
Hmmm that is a lot of ballast. I got no idea where the hell to put 120 kg on a zx1200, may be I should us the missus!
Anyway I own a metal casting business so a couple of well fashioned lead weights may do the trick near the swingarm pivot point. Going to put the bike back onto the Dyno late next week and run it up for a full mile WOT and see if the gas lasts. Getting closer to nailing this I hope. In regards to top speed I have an engineer friend who did some calculations and he thought factoring in 6% slipage, hp and no head wind other than what I create and with all fingers crossed top speed of 207mph. based on actual hp being 197. I have not factored in the ram air on the Kwaka and thats supposed to be an even 10. Whats your experience with ram air? All I know is when this bike gets up around 9 grand it gets a second wind, not including the nos.
Thanks again for your comments.
Cheers Paul
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David Leikvold
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Re: Gearing on zx 1200r

Post by David Leikvold » Tue Apr 17, 2012 7:26 pm

Paul,

I don't race a bike so make of my comments what you will. I'd always thought that having ballast on the sprung part of the bike would be a better idea than making the swing arm really heavy because it would improve the sprung to unsprung weight ratio and not overpower the rear shock with a huge increase in momentum. I know successful salt bike racers have heavy swingarms so it obviously works, but could it be better? Why don't you cast up a giant aerodynamic lump of lead and hang it under the fairing between the wheels? That would keep the front / rear balance closer to original and push both tyres harder into the salt. Just a thought.

Cheers
Dave :D
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kermitracing
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Re: Gearing on zx 1200r

Post by kermitracing » Tue Apr 17, 2012 8:33 pm

Hi David,
Thanks for the comments. You are very right about the sprung V's the unsprung. Unfortuatly every availble space on my bike is filled with something else but it is a thought, to somehow load up balast somewhere other than the swing arm. There are somehard to get to spaces behind the motor which you could add some weight but getting weight over the drive wheel must be more benifical for traction than general weight distribution. I have been thinking over the past 6 months about tyres, their the most obvious point to start with to improving slipage. Given time there must be a way of developing a tread patten and tyre material combination that would improve traction on salt or am I just tackling the wrong end of the problem? Of course they would have to be comercial viabile. Much to learn, not so much time to do it in!
Cheers Paul

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Re: Gearing on zx 1200r

Post by Stayt`ie » Tue Apr 17, 2012 8:52 pm

Your not wrong about the 12`s second wind after 9-10 grand, :D , i was doing some dyno work with mine a cuppla years back, the young fella operating the dyno, ears disapeared into the corners of his mouth when the thing took off those revs, the expletive`s he utted when all quietened down was priceless, :lol: :lol:,,
your engineers calcs seem to be pretty close to mine, the difference, i would think, is mine have the ballest weight factored in,, my "rule of thumb" on the ram air effect is +2.5% on hp@rpm@speed after 190mph, obversley that % differs with velocity, but 2.5, i found, is a pretty good average ,, at 200 you get almost .7psi increase, 8) ,
dont concentrate all ya weight on the back wheel, handling "will" suffer, there are some on here that can testify to that,, as said before keep wheel bias within 60/40, 50/50 is perfect, and keep the weight low,,, my 12 when it had standard wheelbase, no ballast, in startline condition, came in at 297lbs (43.5%) frount wheel, 385lbs (56.5%) rear wheel, so you can see that it dosent take much to go beyond that 60/40 limit,,, extending the swingarm throws more weight forward at the expense of the rear,, i "will not" get involved in the sprung v unsprung debate,, for the record i run, have always run a solid strut in the rear,,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

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