guys i have a non running VFR400 nc21 that the previous owner fitted a second hand NC24 engine into. He could not get it to run as he thought is to be a straight swop. I got the bike for a steal knowing the cdi's are not compatible. I have various options now. 1 is to fit a NC24 loom and CDI. 2 is to mod the CDI to work with the NC24 pickups. 3 is use the NC21 loom and mod it to take a NC24 CDI. Believe this has been done. I cant find any wiring diagrams for a NC21 anywhere. Can anyone help me with a wiring diagram, pin out diagrams for NC21 and NC24 CDI's or just general info from anyone who has done this.

Edit: after stripping fairings and wiring loom from bike and talking to Neo our moderator i was made aware that my bike actaully is running a NC24 loom and a OKI CDI that's actually a NC24 cdi. Making the cam sensor obsolete. How do i get this bike running? Cheapest possible way?

Update: I have removed the fairings to find a NC21 motor and not a NC24 as told. Thats good news, as i think it might be something very simple. The wiring is a nightmare as wires has been cut and connected to seemingly not corresponding wires. Volt reg isnt connected at all. Red, black and blue wires standing alone going nowhere. Cam sensor also never connected.... do need a wiring diagram as i need to trace the wires that was cut...

SpawnOS wrote:Update: I have removed the fairings to find a NC21 motor and not a NC24 as told. Thats good news, as i think it might be something very simple. The wiring is a nightmare as wires has been cut and connected to seemingly not corresponding wires. Volt reg isnt connected at all. Red, black and blue wires standing alone going nowhere. Cam sensor also never connected.... do need a wiring diagram as i need to trace the wires that was cut...

If it has a cam sensor in the motor then its an NC21 engine.

Do you have the ignition box in the rear seat (Oki unit) or the long thin denso one by the battery?

Perhaps the owner got confused and it was a different engine transplant? Or maybe more sinister

perhaps they gave up with the nc24 conversion and put the original knackered motor back in? Ever heard it run.. ive seen things like this before where somebodys tried to replace a dead motor, gave up and sold it as a non-runner with the original knackered motor in it..

whats not connected and / or whats seemingly connected wrong? i should be able to dig up an nc21 wiring diagram

that was my initial thought but im safe. I have the receipt for the new motor and engine nrs match. New motor bought Nov 2013. I need to know where the cam sensor plug connects to. The red, blue and black wires on the volt reg also need to go where? The bike is fitted with the OKI unit under the rear seat. Hope this helps? Any way you can maybe scan in the wiring diagram and post it or even mail it to me? Would be much appreciated

SpawnOS wrote:that was my initial thought but im safe. I have the receipt for the new motor and engine nrs match. New motor bought Nov 2013. I need to know where the cam sensor plug connects to. The red, blue and black wires on the volt reg also need to go where? The bike is fitted with the OKI unit under the rear seat. Hope this helps? Any way you can maybe scan in the wiring diagram and post it or even mail it to me? Would be much appreciated

ill dig out the wiring diagram.

Sounds like you have an nc24 ignition unit, and perhaps loom which is why it doesnt match up, as the NC24 has no plce for the cam-sensor.

The reg/rec sould be the same though.

I have a pretty shitty cold at the moment but in a day or so when im feeling better ill have a scout around for the manual and scan you a copy in of the diagram.

Thanks Neo. I dont think its a NC24 loom. There is a two pin plug cut from the harness and i think thats the original cam sensor connection? Blue and a white wire. This is on the cdi unit: MLO Lot nr 9522, Oki electric industry co

SpawnOS wrote:Thanks Neo. I dont think its a NC24 loom. There is a two pin plug cut from the harness and i think thats the original cam sensor connection? Blue and a white wire. This is on the cdi unit: MLO Lot nr 9522, Oki electric industry co

Thats an NC24 igition unit.

The NC21 is a Denso unit with 3 red plugs on it, its connected up by the battery. (as as you noticed, in that diagram on the other link...) the NC24 unit only has 2 plugs and sits in the seat.. if you have it you have an NC24 loom

NC24 Ignition unit


NC21 Ignition unit


NC21 Ignition unit location

Thanks Neo! Dammit so im still nowhere. Ok whats the CHEAPEST way to get this bike running? Sell loom and cdi, buy nc21 loom and cdi, or get a nc24 trigger wheel and install on clutch hub?

SpawnOS wrote:Thanks Neo! Dammit so im still nowhere. Ok whats the CHEAPEST way to get this bike running? Sell loom and cdi, buy nc21 loom and cdi, or get a nc24 trigger wheel and install on clutch hub?

Hm..

The trigger shouldnt make much difference i think its probably the same part.

Is the ECU you have producting any sparks? I think you can run an NC21 engine with an NC24 system but not the other-way around as the nc21 ecu expects camshaft signals but the nc24 doesnt.. im pretty sure its been done before.

The only difference you should have plugging in an NC24 loom / ecu to an NC21 engine is that the plug around the neutralswitch is different as it uses a different neutralswitch setup. and youll need a bit of splicing there.

bit of a long thread now, just go over brieftly what you have now, any sparks? anything happening at all?

Ok i tested everything on bike, and all lights and switches is working. Bridged radiator fan and heat gauge and both work. Yet to test fan switch in warm water to see if it will switch fan on. I have yet to plug in the cdi. I removed the clutch cover to see what trigger is used. Its a 2 pickup system 90deg apart and two trigger teeth 180 deg apart. Is this standard on both NC21 and NC24? If not, what is the setup for the nc24. Want to get her running, so i can spend time on the important stuff. Customizing the bike!