Hi,

I've got a 1989 VFR400 NC30 and I've trimmed the road gear wiring from the loom and have kept the starter and charger circuit. I'm looking to add the 2k resistor mod to the wiring loom to derestrict it from the 180km/h limiter.

In the wiring diagrams below you can see they both have a resistor mod added to the loom. Both diagrams look to be the start and charging circuit looms for the VFR400 (unless I'm wrong?)

The first diagram has the resistor is in the top left corner, and the second one in the bottom right corner.





Which one is the correct wiring loom to follow?

Or are they actually different resistor mods for different purposes?

Thanks

Either place would work although the colour of the speed sensor wire going into the CDI in the second image is misleading. As long as you connect the orange/blue wire to a 12v source via a 2.2k resistor it will work and remove the speed resistriction.

dont even need a resistor, the hrc box connects it directly to 12v. you can always modify the clock internals, which will give a stealth look, unbolt the clock and pull off the metal tang with some pliers and your done, but if your removing the clock then its out the question :)

Neosophist wrote:dont even need a resistor

+1

just run a wire from +ve 12v (battery terminal if need be) into the orange/blue wire.

Cammo wrote:

Neosophist wrote:dont even need a resistor

+1

just run a wire from +ve 12v (battery terminal if need be) into the orange/blue wire.

ive got a photo somewhere of one of the HRC SP units cut in half, nothing inside it just a passthrough with the orange/blue wire spliced to a 12v wire.

I think that puts to rest ebay sellers of claims it does something to bhp and what not.

Thanks for the replies, although starting to get confusing with the contradicting advice,

Bit of a noob question, but what is the point of the resistor?

I've seen a resistor used on another Honda loom to derestrict it, so if it isn't needed, why is it added to both diagrams above?

I'm curious as to the answer myself. I was led to believe that the CDI expected to see a 9v or something similar signal from the speedo sensor hence the use of a resistor. This goes back at least 15 years to when i first saw this done on an NC30 and i'm sure before that.

Could it just be one of those things where someone tried it with the resistor, it worked, and that then became how it should be done when the resistor was never really required?

Another possiblity it someone came up with the mod by cutting up one the the 'M-Max' or similar plugin speed derestrictors that they used to sell for £40 odd and they had put a resistor inside to make it look like the box actually did something rather than just short two wires?

I've taken the speed limiter guts out of the speedo, and mounted it in a small plastic box. This is zip tied to the instrument bracket. I'm not running the speedo on the NC30 as it's a track only use bike.

gavins wrote:Could it just be one of those things where someone tried it with the resistor, it worked, and that then became how it should be done when the resistor was never really required?

Another possiblity it someone came up with the mod by cutting up one the the 'M-Max' or similar plugin speed derestrictors that they used to sell for £40 odd and they had put a resistor inside to make it look like the box actually did something rather than just short two wires?

Both are plausible theories!

Does this race bike have a speedometer? You don't need a resistor anywhere if you don't have a speedometer cable spinning the speedo gears and a speedometer needle past 180kph, as the restriction circuit will never be activated. You will need to do what GeeTee said, though, as the ECU expects to see the circuitry.

Ciao,