Making a KTM 450 SMR Street Legal - Electrical

So, I just bought this thing. It was advertised as "I've got everything to make it street legal." Well, yeah, sort of. I don't think it's ever been street legal but at least I have a plate for it and the plate number is already on the title so registering it shouldn't be a big deal. I was told that it's been upgraded to a 300W stator.

So here's what I got in my box of parts that came with the bike:

1 - Four little Lockhart Phillips turn signals. I've already figured out how and where to mount these.

2 - A nifty little aftermarket LED running/brake/license light that will fit nicely under the rear fender. I'll need to fabricate some mounting hardware to get that and the plate on the bike but I've got that figured out.

3 - The rear brake switch is already installed. No connector on the end, just bare wires. I tested it and it works.

4 - No front brake switch. But I've got a switch from a BMW in my basement and I've figured out a way to install that to work with the KTM brake lever.

5 - A KTM headlight. I installed that today. The front brake line is a little short to make it over the front of the new headlight panel so I had to run it behind the panel. No biggie.

6 - What I'm pretty sure is a non-KTM headlight/turn signal/horn combination switch. I used a continuity tester and have figured out the wiring on that.

7 - No horn. I've got some spare horns in the basement so that's not a big issue.

8 - No mirrors. At least for now I'll get some bar end mirrors on Fleabay so it's at least legal.

9 - A KTM mystery wiring harness. I can read the KTM on the tag but no part number. From looking at the wire colors and some KTM wiring diagrams I've deduced that the little black box I've got attached to the harness is the voltage regulator/rectifier.

Since the lights and switches are non-KTM they have different connectors and won't "plug-n-play" with the KTM harness I have. So I'm thinking that my best bet is to use the regulator/rectifier and some turn signal relays and just build my own wiring harness. I've done lots of electrical mods to my other bikes so I'm not a nOOb at wiring and I think it should all be pretty straightforward.

So my plan would be to take what shows on the wiring diagrams as yellow and white wires from the generator, run those to the regulator/rectifier and then power my lights and horn from the yellow-red coming out of the regulator/rectifier.

Does this seem right to those how know KTMs?

Oh, and I plan to use a TomTom Rider GPS as my speedometer/odometer.

Well, it sounds like you've got most if not all of the bits and pieces you need.

A voltometer and test light are going to be your new best friends. A small 9V battery with some leads will help test bulbs and stuff.

I'd start by testing the turn signals and lights just to see if they work before attempting to wire them up.

Nothing more frustrating then trying to make a burnt out light work!

If the new harness is routed you might test the termianls at the ends of the wires for power and see if they blink,stay on for running lights,etc before cutting the plugs off. Keep your battery on a tender you'll need it.

I'm looking at putting turn signals on a 525 MXC soon so I'll probobly be doing alot of the same trial and error stuff your going through.

Just out of curiosity how much did you buy the bike for?

KTMs always seem grossly overpriced in WA.

I paid $4k for it. I really tend to believe that it has incredibly low hours given how clean it is. There isn't a spec of dirt on it and the air filter looks brand new.

Anyhow, the plot thickens:

I emailed the following picture to Trailtech tech support guys to see if they could be of help in determining what I've got.


Their reply was that it didn't look like theirs but was probably stock EXC Parts. From looking at a few EXC wiring diagrams and the wiring colors I think they may be right.

Here's the wiring harness that came in the box of parts with the bike. The guy told me at was a Euro EXC harness but given other misinfo from him who knows? (He bought the bike a couple of years ago and didn't do much with it.)


The part number on the tag is worn and hard to read but I THINK it is 594.11.07?.000

Here's the voltage regulator on the wiring harness:


From the KTM wiring diagrams I've looked at the colors to it's connector seem to agree: Brown, Yellow, White, Yellow-Red:


Here's a sample from a KTM EXC wiring diagram which leads me to beleive that I mihgt be able to just connect the voltage regulator to the yellow and white wires and get 12V DC out of the Yellow-Red wire: (with the brown wire grounded of course)


So the question becomes how many watts can I get from the stator?

I pulled the bulb from the EXC headlight I've installed and it says it's 35/35W.

In addition to that I need to run an LED tail light setup (as LEDs that can't draw very much current) and four little Lockhart Phillips 122-0031 turn signals.

In the meantime I fabricted some stuff and got the LED tail light and plate mounted under the rear fender. (I put the turn signals up at a 45 degree angle because it looked like the right one might get melted by the exhaust if pointed straight to the side.)


Thought it might be the same bike. I offered him 3,800 a few weeks ago and he wanted to get asking for it, probobly would have paid 4 but he never counter offered so I passed.

Sweet bike.

He told me he had two offers of $3800 he'd turned down. Wasn't sure if he was telling the truth but offered him $4k on the spot that I had in my pocket. I was going to go home and get my trailer since I'd ridden there but he offered to throw it in his truck and deliver it to my house in Seattle which was cool. Saved me from having to register my trailer since I only use it for emergencies and don't keep the tabs current unless I need it.

The "I've got everything to make it street legal" was not really true but Im dealing with that.

You got a great deal on it. SMR's never came road legal so you'd have go though the lighting and stator hassle with another one anyway.

I'm torn between the 450 and the 525 right now. Have to make up my mind by tommorow. Traded my Jeep for my buddy's pickup Saturday so I can transport a bike back to Seattle.

Any luck with getting that Euro harness working?

Any luck with getting that Euro harness working?

I decided I'd be better off building my own wiring harness. I'm really comfortable going the DIY route as I've wired tons of stuff on my other bikes so I have a good idea what I'm doing and how to wire stuff so it lasts.

Here's what came with the bike that I'll use:

KTM 35W headlight

KTM voltage regulator/rectifier

4 Lockhart Phillips 122-0031 turn signals

Rear brake switch

Aftermarket LED brake/tail/ license light

Aftermarket headlight/turn signal/horn combo switch

Here's what I've bought:

Turn signal relay ($9)

5 Ah 12V sealed lead acid battery ($15 shipped)

Four slot aux fuse block ($9 shipped)

Bar end mirrors ($25)

(I'll probably need to spend another $10 on open-ended grips for use with the bar end mirrors)

Stuff I've got laying around:

TomTom Rider GPS (running some 3rd party software

to serve as a large digital speedometer)



BMW K75S dash pad with igntion swtich/key - that looks like it will work OK on the KTM bars. It has a three position switch which I'll wire up so it's:

1) Off and bike won't run

2) On with no lights except the headlight will work if turned on at the headlight switch

3) On with power to everything and street legal

If it looks like I've got enough spare power once I've got things going then I'll probably wire up some Symtec heated grips($40) to AC in the fall.

I have some spare sheet aluminum in the basement to I plan to make my own mounting plate for under the seat and mount the following components to it to keep things organized:


Voltage regulator

Power relay

Turn signal relay

Fuse block

For grouping/protecting the wires I have a cheap local source for various sizes of heat shrink tubing in four foot lengths.

Here's a schematic for the wiring that I drafted yesterday. I plan ro run the headlight on AC and everything else on DC.


Everything should be here by next week and I'll dig in. :excuseme:

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