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Tuesday, October 12, 2010

Gear Position Sensor Mod... or... "how to de-restrict power in first and second gear"

One of the most common complaints of VFR1200 owners is the power restriction in first and second gear. My dyno runs from an earlier entry clearly show the "torque hole" that occurs in first and second. I've speculated that the reason for the restriction is to reduce wheelspin in the lower gears. (when Honda should have just equipped the bike with proper traction control) I've also speculated that the restriction was the result of a "traction map" that reduced the throttle opening at those specific RPMs in 1st and 2nd.

A fellow enthusiast on a discussion board argues that the restriction is a result of a timing retard in those circumstances... which I have no reason not to believe. (this would be a much simpler solution to execute)

That same enthusiast (dutchgixxer on vfrdiscussion.com) hypothesized that the restriction could be eliminated by "fooling" the ECU into thinking that the bike was in 3rd gear while in first and second. This would mean that it would revert to its full power map. He studied the wiring and provided a simple schematic on how to fool the ECU.

The VFR1200 has a very sophisticated gear position sensor (GPS) that uses an extremely accurate potentiometer on the shift drum. I suspect that this is "trickle-down" technology from the DCT version where the GPS plays a crucial role. Each gear position has its own wire going into the grey serial plug on the ECU. This makes it relatively simple to fool the computer.

I can't take credit for the concept of this modification, but I am pleased to provide a set of instructions.


The tank must be lifted to gain access to the ECU.
The grey connector is unplugged.

I cut a slit in the shrink sleeve to gain easier access to the wires. I separated the black and yellow wire. This is the 3rd gear wire which is grounded when the GPS detects that the transmission is in 3rd gear.

I carefully stripped away a bit of insulation and spliced in 2 short pieces of wire. I twisted them together, used a little blob of solder and taped it up.


The black and brown wire is the first gear wire and the light green and red wire is the 2nd gear wire. The third gear wire is spliced into the 1st and 2nd gear wires on the sensor side. I taped the ends of the wires on the ECU side to prevent shorting.


All taped up and back together. Now when the transmission is in 1st or 2nd gear, the ECU will get a 3rd gear signal. Full power will then be available in those gears. The only drawback is that the gear indicator display will give a false reading in 1st and second. It will read that the transmission is in third gear.



It could be a while before I ride again but I'll report back on how the mod changes the power delivery.

22 comments:

  1. Nice Idea. Looking forward to your trial report. Also I am wondering how this can work with the DCT version that I have!!!

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    1. BAD AZZ ON EBAY MAKES A IN-LINE PLUG THAT DOES THIS FOR 60 BUKS BEST 60 BUKS I EVER SPENT MAKES POWER VALVE IN EXHAUST OPEN AT 4000RPMN INSTEAD OF 6 ALSO

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  2. You definitely do NOT want to perform this mod on a DCT bike. The ECU on a DCT needs absolutely accurate information on gear position.

    This mod could cause serious damage to a DCT bike.

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  3. I'm looking forward to your trial report as well. One thing that hit me however (understand that I've never ridden a VFR1200F) is that it would be possible to confuse second/third gear on the bike while riding. Why not wire from 6th gear to 1st/2nd as you'd get a displayed distinction between 2/3 and you'd obviously know you were not in 6th.

    As I said, can't wait to hear of the seat of the pants difference however.

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  4. Good idea Matt. The gears are spaced pretty widely in the VFR so it's pretty obvious what gear you're in for the first 3 gears by feel. 4th 5th and 6th are where the indicator comes in handy.

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  5. I may have misunderstood your instruction above, though I believe that it will be necessary to cut the 1st and 2nd gear wires to the CPU so that the CPU does not see two or more gears indicated at one time. This would be recognized as a fault and would result in a "-" sign on the gear indicator display. Therefore 1st and second gear wires should be cut with the ends coming from the GPS both tied to the 3rd gear wire. The 3rd gear wire does not get cut of course. Maybe that is what you did.
    I plan to install a switch to that I can switch between full power mode and stock mode on the fly. It just takes a DPDT switch and some wire that I will run under the plastic to just in front of the tank.

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  6. That's actually what I did Gary. That way the ECU will never receive a 1st or second gear signal. I actually picked up a DPDT switch and plan to do the same. I plan to mount the switch under the seat. I'll detail it all in a future entry... probably soon.

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  7. Sensors are transforming the way engineers think about position sensing

    Distance Sensor

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  8. I've seen it mooted that the override isn't about wheelspin but is to prevent the gearbox being overloaded at low speeds and in high torque gears.

    This makes sense but maybe Honda have overdone it a bit?

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  9. all modern bikes are built really well with masses of power for the road rider or even pretty brave semi-track guy.when did you last red line your bike throu 5 gears?or even 3? often people come to me as a bike mechanic and say "how can i make my bike go faster?power commander?, noisier exhaust,spend more money?please tell me i want more speed ect". to be honest how many people even use 70% of their throttle OR rpm. you have 6 or 7 gears for more torque and a lot of rpm and normally 50% more throttle to twist if you want more power. let alone doing the pair together? not many me included.drop it 2 and twist the grip. thats what is for!!! LMAO

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    1. Redlined in 1st through 4th yesterday. 1st through 3rd just about every time I take it out. I ride it like I stole it, every time.

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  10. Well put, I agree entirely there :)

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  11. @Peter: I suppose it is possible that Honda included the restriction to preserve the "side gear case" which is the complicated gearbox that constitutes the 1200's final drive output.... however, I think the restriction is to limit wheelspin. The reason I think that is because I now know how prone to sudden wheelspin it can be.

    @Anon: I think it's more about personalization than looking for the max performance. My slip-on exhaust is there for looks and sound, my PC5 is there to smooth it out now look for a few more hp. The de-restriction is there because I want to feel what this bike is truly capable of. I happen to be one of the few who truly will run the bike to redline through 4 or 5 gears every time I get on it, and thrash it at the racetrack once in a while... but you are 100% right... it's fast enough without changing a damn thing.

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  12. I read a comment today that you and DutchGixer put your bike back to stock because of wheelspin issues. Is that the case?

    I've also been looking through the Honda shop manual and there no mention of the GPS on the DCT bike.

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  13. That's not true in my case. I've left it derestriced and never switched it back.

    The GPS is a key component on the DCT bike as the ECU needs to know which gear its in. So far there is not a derestriction method for the DCT version.

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  14. Great info. I was looking up to see what exactly Honda does to limit power in 1st and 2nd gear and I came across this article. The 2012 model now has 'Traction Control' and some added power between 2 and 4k RPMs... Do you know if the '12 model added traction control and dropped this feature? I'm seriously considering upgrading to the VFR1200 from my 919 but a few things like this are keeping me from pulling the trigger.

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  15. It's probably an ignition timing retard but I always suspected that it might be a clipped throttle map. The '12 with traction control will not have the power restriction.

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  16. I have a 2012 manual clutch, the power restrictions still remain in 1st and 2nd. I havE the Dyno Sheets From Dyno Jet available on the vfrd form page. Screen name dados even

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  17. Will the de-restriction hamper the warranty of the bike?

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  18. probably. My bike only came with 1 year of warranty so I didn't really care. Also, here is the amount of warranty claims I've had to make on all the Honda motorcycles I've owned: _____

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  19. Good answer, thanks, tell me please, is there another restriction in 6th gear to lower top speed?

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  20. Expensive , good afternoon !
    It's the first time I participate on the blog . Congratulations for information. I have a VFR 2011 and here in Brazil did not come this motorcycle with its center stand . Do you know if there is a similar one that I use?
    Thank you

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