JDC
Zone Head
Posts: 570
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posted January 06, 2010 07:18 PM
John,
It'd be my guess that it doesn't kick in because you haven't likely hit 186 with it yet in your car.
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laverda1200
Parking Attendant
Posts: 23
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posted January 06, 2010 10:40 PM
Hi John
I am no expert, but....
the ZX 14 as well as various other current bikes are limited, by agreement amongst the major manufacturers, to 300 kph, 186 mph. That has been the case for several years now. For example,I believe it is the 99 Busa that is not top speed restricted, but all subsequent model years are. All years of ZX 14 are top speed restricted.
to defeat the top speed limiter, the aftermarket "fix" is to interfere with the signal from the speedo sensor to the ECU, fooling the ECU by not letting it receive a signal indicating 300 kph or higher. If you look at a "Speedo Healer" it works by connecting between the speedo sensor and the ECU, and allows the signal output from the speedo sensor to be "adjusted" to cause the ECU to receive a signal indicating a lower speed than the bike is actually travelling.
For example, you could adjust the speedo healer to tell the ECU that the bike is "only" going say 200 kph when it is actually travelling at 300 kph, which then prevents the top speed limiter from operating. With that adjustment setting dialed into the Speedo Healer, the ECU will never see a signal of 300 kph. What I don't yet know or understand is how the ECU institutes the top speed limiter at 300 kph, does it cut fuel, retard ignition, cut power to the coils, what?. I also want to know if the speedo sensor signal in any way affects the timing map or the fuel map.
so, your race car will hit a top speed limiter only when the ECU sees a signal from the speedo sensor of 300 kph. Do you have the speed sensor wired up in a race car engine installation?
Shane's thread does a brilliant job of describing his quest to break 200 mph within a standing mile, and his timing slips show speeds above 186 mph. I saw mention way back in his build ttread that he is using a speedo healer. I will be running on a 3 mile salt course at Bonneville, with a lot more distance to achieve whatever top speed the bike will reach, I saw mention in Shane's build thread that Shane reached 211 mph on a 1.5 mile track, I doubt I will get anywhere near that on the squirmy salt in the heat and high altitude of Bonneville, but being the eternal optimist that I am I will be installing either a "Speedo Healer" or a Muzzy's" Bonneville Pro" if someone hasn't cracked the ZX 14 ECU by the time I go to Bonneville.....
another way to fool the speedo sensor to alter the signal going to the ECU is to physically modify the corners of the bolt that the sensor takes its readings from. You can halve the signal from the speedo sensor to the ECU using jusyt a file on the trigger bolt, for example.
If defeating the top speed limiter were to be as simple as unplugging the speedo sensor, for example, and doing that did not affect the ECU fuel or timing mapping, I would do that in a heartbeat, the speedo isn't all that accurate anyways, and I will have a GPS mounted for showing actual speed.. I wonder if just unplugging the speedo sensor would defeat the top speed limiter without adversely affecting any other systems? Anyone?
Paul
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laverda1200
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johnbull
Expert Class
Posts: 314
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posted January 07, 2010 01:27 AM
So Paul as you mentioned above, the speed sensor is the one inside the front sprocket cover which reads off the 4 sided sprocket nut. This means that it is reading actuall output shaft revs and not km per/hr from the wheels correct?
As JDC mentioned above, the car obviously hasnt reached 186 actuall mph BUT since we are running much lower gearing than a motorcycle, we are still reaching maximum revs in 6th gear and hitting the limiter..........so since the sensor reads off the output shaft, isnt this the equivalent of a bike reaching max. in 6th gear????
What I am trying to say is that it all depends on what sprockets you are running. So Paul if you were to gear your motorcycle higher than standard then your top speed limiter would kick in at a higher speed that 186mph correct?? and vise versa, since my car is geared much lower then the top speed limiter should kick in at a much lower speed than 186mph.
The speed sensor must be calibrated to calculate a top speed of 186mph with the stock gearing. Once you change the gearing the 186 limiter changes.
What I was trying to say in my 1st post is that when the car tops out in 6th gear due to its low gearing, how would I notice if this is the speed limiter and not just the normal rev limiter like there is in every other gear??
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John Bul Racing. Malta.
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laverda1200
Parking Attendant
Posts: 23
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posted January 07, 2010 10:15 AM
Hi John
I don't know. I am hoping someone with some technical expertise in this area chimes in......
Paul
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laverda1200
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johnbull
Expert Class
Posts: 314
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posted January 08, 2010 02:55 AM
Anyone out there with technical expertise that can confirm this???
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John Bul Racing. Malta.
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