Tach hook up on '02 426

Anyone know what color the low voltage wire to the coil on '02 WR426 is (orange)? Looking to hook the tach up directly instead of wrapping the plug wire.


You should have an orange and a black to the coil, use the orange.  I hooked up the tach lead to a Vapor to the orange and it read much better than wrapping around the spark plug wire.  

Thanks! Hooked it up tonight but it reads 8000 at idle. It's a Vapor unit also, did I do something wrong? Spliced into orange wire and soldered and used heat shrink. Thought that would be nice clean way to go. Puzzled because it worked wrapped around the plug wire.

Yeah , recently added a vapor to my 98wr400. First tried the wrap method, but got varying results so I tried the orange coil wire and had the same result as you mention with the high rev shown. In the end I found a forum thread ( I think it was TT) and it had info from a trail tech technical guy. He gave instructions including pictures for connection to a green (from memory, can check when I get home) wire that runs through a plug under the fuel tank (right hand side) to the computer. You can pop the pin out of the plug, wrap the tachometer wire around the pin and push it back into the plug. Vapor has worked perfectly ever since.

Thanks Jedmeister and flyandride! I think I may need to change the ppr setting but I'm unsure as to what to set it at. Does it change pulses at a certain rpm?

I tried that too but didn't find that it solved the issue. I spent hours trying to work it out as I'm no elec guru. Got very frustrated until I found the above mentioned thread. Too bad that you've already soldered etc. I've got a bit of shortened wiring too from cutting the wrong wires :-)

Is anyone sure if the green wire is correct to tie the tach into? Just  like to be sure, I'd hate to fry my computer or something else. Talked to Vapor tech line but they weren't much help, just said it was probably electrical noise and I'd have to live with it.

Sorry old triumph guy, been hectic at work.

I've taken a pic for you, just need to figure out how to post it.

As a bit of further explanation. I've got two wires running from the vapor to the plug between the stator and the computer (black box/rhs of frame neck) (both wires are black as I previously cut the black and red (?) one too short and ended up extending it with black off cut :-/).

One joins the green wire and the other joins the black wire as described in previous post. My engine is in many pieces for a rebuild at the moment so the stator is out of my bike.

As I mentioned previously, I'm no auto elec, so when I joined in the vapor wires to the plug, I just connected them straight in with no forethought for future disconnection. When I went to remove the engine I came across the hard wired wires and just labeled them and cut them for reconnection with plugs.

The vapor is good for very high voltage, according to the manual, so I would just try connecting to the vapor wires to the stator loom wires described above and see if it makes any difference to the rev readout. ( sorry I don't have time to strip my wiring for you, to find out at the moment :-( )

Good luck,


No luck posting the pic I'm afraid. Sorry about that. Hopefully my explanation will suffice. Give me a yell if you need further clarification.

Cheers, Jed.

Here's your wiring diagram.  It's exactly the same as an 01 wr250f which is what I have.  I connected the vapor to the orange going to the coil and the tach works perfectly.   The green you are talking about comes from the charge coil to the CDI.  It looks like it could work.  But I have converted mine to a full DC system with a battery to make the DOT happy.  Vapor is powered from the 12V battery. 

WR250F wiring.jpg

Edited by flyandride

Thanks flyandride and Jedmeister! That helped greatly! I'll give it a try this weekend to see if it helps.

Hey old triumph guy,


Flyandride has got my brain ticking over and I think I may have been leading you astray with my previous posts. 

If memory serves me (and I feel it may have let me down in the above), it was the power connection I had for the vapor that was causing the rev readout to be WAY high.  I had it connected to some random wire that was providing power to something around headlight/headstem.  When the vapor was disconnected from external power and running on its own battery, the rev count was correct, but when I tried to power it from the bike (ie to run background lighting) the rev counter went haywire!


Flyandride is correct in that the rev counter should be connected to the orange wire, I believe the tech guy is correct in saying that the issue is being created by electrical noise.


It was the POWER connection to the green/black wires on the stator to ecu(? Black box) loom that sorted out the problem!


Humble apologies for having led you a little ways down the garden path!


And many thanks to the guys on TT like Flyandride who actually know what they are talking about!




Thanks Jed! I think I'll just go back to wrapping it round the plug wire and tape it up. I was just looking for a good way to clean up the install. Hope to be able to ride this weekend and check it out.

Appreciate all the help guys!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now