Removing the speed limiter from the P model

[beardo]

I hate getting into threads like this because people always interject their opinions about speed.

I just want black and white facts.

And no one, still, seems to know for sure.

 

[rogo]

Police units are limited to 128 MPH.
Here’s what you need.

 

[beardo]

No, it's a hard 120. It's repeatable....each and every time.

 

[Larry Fine]

I think it was said above the ECU knows the speed the same way the speedometer does - off the crank sensor.

Wouldn't the speedo drop if you pulled in the clutch (and let off the throttle) while moving?

 

[beardo]

This isn't the first bike I've had that I've run to the limiter. Experienced it many times on many bikes.



For anyone who has never experienced it, it feels like a wall of rapid fire misfire, extremely precise. You can hold the throttle there all day long....you aren't going to go any faster. That's the point. And that's the principal I'm completely against. There are no new riders on these machines.



So, I say once more, though I think at this point I have my answer, does anyone have a concrete solution to this issue, one that they themselves have actually rectified?

 

[SMSW]

Wouldn't the speedo drop if you pulled in the clutch (and let off the throttle) while moving?

The speedo healer must be programmed in each of the gears, so there must be a sensor which tells it what gear its in. I don't know for sure, and I thought my previous post indicated this was speculation on my part.

 

[Andrew Shadow]

does anyone have a concrete solution to this issue, one that they themselves have actually rectified?

No personal experience, but I have read (somewhere on this forum I believe) that the speed limiter is integral to the ECM. If so, replacing the Police spec ECM with a civilian version ECM should take care of it. Expensive fix however, so you might want to borrow one to try it first to confirm this, unless somebody here knows this for a fact.

 

[ST Gui]

So, I say once more, though I think at this point I have my answer, does anyone have a concrete solution to this issue, one that they themselves have actually rectified?

Best of luck with that.

 

[ad.hom]

I hate getting into threads like this because people always interject their opinions about speed.

I just want black and white facts.

And no one, still, seems to know for sure.

No opinion here.

The earlier P models have a limit to a calibrated 128mph (why? Because that's far easier bitwise logic than 120, compute power is limited in an ECU). You experienced it at 120, likely because it's been a while since the speedo was calibrated and it's drifted.

You have a few options:
1) Civilian models never had that limit, swap the Police ECU for a relevant year Civilian ECU (someone recently did the opposite, from Civ to P, and it worked fine, I'm not sure from the top of my head what features of the P ECU you might "lose").
2) As mentioned before, later P models did not have the limit, source a compatible year P ECU without the limit, and swap for that.
3) In-line aftermarket unit to modify the crank sensor pulses. I've never been brave enough to do that on any engine, at best, your fuel map would be wrong above 128mph, at worst, you could end up with a bang that should have been a suck. That would truly suck (though I like to think that the safety controls would shut the engine down rather than destroy itself... I wouldn't want to be hard on the gas and my engine be shut down either though).

For whatever its worth, the members that replied before I did are amongst the most knowledgeable folk I know. You're asking about a thing that many will deem "crazy" to even contemplate. I often find a little humble pie helps to grease the wheels.

Finally:

one that they themselves have actually rectified?

Nope - I have never owned nor ridden a ST1300P - of any year. Nor do I have any desire to regularly ride at speeds where I would lose my licence, my ST1300A2 is more than fast enough for me. I have done a fair bit of work on engines, electrics and tinkered with more than one ECU, though.

You're welcome to take my comments with as much salt as you can hold. Good luck with your research.

 

[beardo]

No opinion here.

The earlier P models have a limit to a calibrated 128mph (why? Because that's far easier bitwise logic than 120, compute power is limited in an ECU). You experienced it at 120, likely because it's been a while since the speedo was calibrated and it's drifted.

You have a few options:
1) Civilian models never had that limit, swap the Police ECU for a relevant year Civilian ECU (someone recently did the opposite, from Civ to P, and it worked fine, I'm not sure from the top of my head what features of the P ECU you might "lose").
2) As mentioned before, later P models did not have the limit, source a compatible year P ECU without the limit, and swap for that.
3) In-line aftermarket unit to modify the crank sensor pulses. I've never been brave enough to do that on any engine, at best, your fuel map would be wrong above 128mph, at worst, you could end up with a bang that should have been a suck. That would truly suck (though I like to think that the safety controls would shut the engine down rather than destroy itself... I wouldn't want to be hard on the gas and my engine be shut down either though).

For whatever its worth, the members that replied before I did are amongst the most knowledgeable folk I know. You're asking about a thing that many will deem "crazy" to even contemplate. I often find a little humble pie helps to grease the wheels.

Finally:

Nope - I have never owned nor ridden a ST1300P - of any year. Nor do I have any desire to regularly ride at speeds where I would lose my licence, my ST1300A2 is more than fast enough for me. I have done a fair bit of work on engines, electrics and tinkered with more than one ECU, though.

You're welcome to take my comments with as much salt as you can hold. Good luck with your research.

This is excellent information and I greatly appreciate your taking the time.

 

[TerryS]

What is all this talk of the speed sensor coming off the crank? It sits in the back of the gearbox area adjacent to the shaft, so almost certainly simply picks up the final drive speed irrespective of gears and crank. Other similar era chain drive Hondas have the speedo drive off the countershaft sprocket (directly onto the nut on the sprocket) or off the output shaft just inboard. So changing a speed sensor (e.g. adding a speedo healer) won't cause the bike any running issues.

The 1997 JDM VTR1000F that I bought had a 180km/hr speed limiter which felt just like hitting a rev limiter. I don't make a habit of riding faster than that (actually seldom more than 140km/hr) but as Beardo points out, it's the principle involved! On that bike there was an extra wire heading back from the speedo to the ECM, and disconnecting it defeated the limiter. I assume that when the speedo needle swept beyond 180, a circuit was closed that triggered the limiter. If you could get the wiring diagram specific to the Police model and compare that to the standard bike, you may be able to see if there is an extra wire to the speedo/dash in the smaller of the two multi-plugs.

 

[dwalby]

The earlier P models have a limit to a calibrated 128mph (why? Because that's far easier bitwise logic than 120, compute power is limited in an ECU). You experienced it at 120, likely because it's been a while since the speedo was calibrated and it's drifted.

Its been decades since programmers would have to be that efficient to use an even power of two like that, CPUs aren't that slow and primitive anymore, even in the early 2000s when the 1300 was developed. The even power of two values were used for things like division, where dividing by 128 is just 7 bit shifts right compared to a much more complex division algorithm for any other number. But, if they're just trying to compare one binary value to another, then you have to compare all the bits, so even powers of two generally have no advantage there. And, since the 1300 has an analog speedo, there's no other need for a digital speed value in the system, so its unlikely one exists at all.

Terry's explanation makes sense, but its for a different bike, so its not clear if it applies to the ST1300P. The 'enable' wire that triggers off the speedo needle position could theoretically be the same for MPH and km/h units, just a different silkscreen on the dial for the two different units. The sensor at the final drive would then just need to measure shaft RPM and it would be the same for MPH or km/h.

edit: when I first saw this thread I though it was very odd that a police bike would have any speed limiter at all, was this done in response to the deaths attributed to the "Pan weave" on the British police bikes??

 

[TerryS]

Its been decades since programmers would have to be that efficient to use an even power of two like that, CPUs aren't that slow and primitive anymore, even in the early 2000s when the 1300 was developed. And, since the 1300 has an analog speedo, there's no other need for a digital speed value in the system, so its unlikely one exists at all.

Terry's explanation makes sense, but its for a different bike, so its not clear if it applies to the ST1300P. The 'enable' wire that triggers off the speedo needle position could theoretically be the same for MPH and km/h units, just a different silkscreen on the dial for the two different units. The sensor at the final drive would then just need to measure shaft RPM and it would be the same for MPH or km/h.

edit: when I first saw this thread I though it was very odd that a police bike would have any speed limiter at all, was this done in response to the deaths attributed to the "Pan weave" on the British police bikes??

I think your theory on the limiter being linked to avoidance of Pan Weave sounds pretty plausible.

I would also bet you are correct that if we were to overlay mph and km/hr on the same speedo we would see that only the silkscreen is changed, and the electrical gubbins and pulse rate from the output shaft are identical. Manufacturers are not stupid, the less they change the cheaper.

It alsways fascinated me that when the tarrif-busting 699 cc bikes were developed from 750's they only changed the crank (shorter stroked) and rods (longer to keep the piston-head distance the same), no other mechanical changes needed. In VFR750s anyway.

 

[Cincykz]

I am certainly not a speed shamer, and despise limiters. I have achieved VMAX on many, many vehicles. I have been gps 189 once, and over 150 many times. The St1300 is my favorite motorcycle. I think Pan Weave is generally overstated. That being said, the 13 is perhaps the least stable bike at these speeds that I've ridden, at least that achieves them fairly easily. My weave experience was at about 135-140 with the top box on. It was mild and I rode it out no problem. I had been at that speed a few times with no issues. I do see that 120 could be an annoying limit on a sketchy pass, and I appreciate your mission and wish you success. Just be careful up there. I've really slowed my roll the last few years. The big bore ZX bikes are extremely stable and very comfortable at those speeds, and also very quiet and fuel efficient.

 

[itsrichierich]

For those that say the later models have the limiter removed, what year is that?

 

[HunterW7]

For those that say the later models have the limiter removed, what year is that?

I've got a 2014 1300 PA and it's got the limiter at 120 as well. To my knowledge that's the latest year so I'm not sure which one would have no limiter.

 

[Ron_WI]

In my experience on my 2007 ST1300, the speedo is way off optimistically. Spedo at 40 is about 34-35 on GPS and 80 is 71 or so on GPS. So if my speedometer said 150 MPH, I bet the real speed would be more like 130-140. I've never actually done a top-speed run on this bike. Accelerating through 4th gear I've seen the speedo swing past 120 but the GPS top speed is under 110. I don't know about the police models as it's mentioned here that their speedo's are calibrated so maybe those are accurate.

 

[ST Gui]

For those that say the later models have the limiter removed, what year is that?

I hadn't seen any reference to a limiter being removed.

In my experience on my 2007 ST1300, the speedo is way off optimistically.

I've read here the speedo on the P (Police) models is more accurate than the civilian version. It would make sense for vehicle speed pacing.

One model of the KZ1000 police bike had two speedos. One was a normal speedo and the second could lock the needle at the violator's speed when he was lit up. I think it was dropped later.

Ford had certified speedos on their LTDs used by a local PD. Their traffic unit would regularly recheck them for accuracy against a radar gun with the date and any differences noted. So even an optimistic bike speedo could be used for enforcement were that the case.

So has anybody removed the limiter on an STP?

 

[kevhatch]

Not sure if I've asked this before and sorry for rebooting an old thread.
It's going to sound silly but I want to do the opposite to the reason of this thread and restrict my 1300Pan.
Reason - I have a 2002 which is stuck in the UK and I live in France - I'm not allowed to register it here because - No ABS and it's 126bhp out of the factory, anything above 100bhp has to have ABS in France. I've done a bit of internetting and contacted Honda France but not found a solution yet ... if there is one!
Cheers

 

[DannoXYZ]

Not sure if I've asked this before and sorry for rebooting an old thread.
It's going to sound silly but I want to do the opposite to the reason of this thread and restrict my 1300Pan.
Reason - I have a 2002 which is stuck in the UK and I live in France - I'm not allowed to register it here because - No ABS and it's 126bhp out of the factory, anything above 100bhp has to have ABS in France. I've done a bit of internetting and contacted Honda France but not found a solution yet ... if there is one!
Cheers

What are you trying to do? Limit speed to 120mph? Or reduce power to 100bhp?