TTR125/L/LE Installing Lights

Existing technical info specific to Yamaha.
Respond to topics with questions or comments.
Post new topics in Yamaha Community.
Post Reply
User avatar
Site Admin
Posts: 1203
Joined: May 02, 2016

TTR125/L/LE Installing Lights

Post by 4Strokes » Fri May 20, 2016 9:46 am

Stock stator with no wound lighting coils
stator.jpg (16.9 KiB) Viewed 5797 times
The Yamaha TT-R125, TT-R125L and TT-R125LE do not come with lights and some do not even come with wound stator coils to power lights. For the ones with no wound lighting coils, modification is required. If you are mechanically inclined or have wound stators in the past, then you already know what needs to be done. If not, you can send your stator out to one of the many stator rewinding shops or just purchase a new or rebuilt stator that has its lighting coils already wound. The picture to the right shows the stock TT-R125L stator with only the ignition coil or poll wound.
Newly wound stator with yellow wire and regulator
woundstator.jpg (22.29 KiB) Viewed 5797 times
The engine must be somewhat disassembled to remove the stator. Before beginning any of the following work, it is advised to purchase and use a good service manual. On the Yamaha TT-R, you must first drain the crankcase oil because the stator resides in crankcase oil. After draining the oil, pull the left-side engine cover off. You will notice by the photos above and to the left, that the TT-R stator is not behind the flywheel like many bikes. It is actually mounted to the backside of the left engine cover and sets into the flywheel when the cover is bolted onto the engine.

Contact or electrical cleaner works good for cleaning oil off the stator. Package it up for shipping if you are having someone else do the rewinding. You may also want to order a new left engine cover gasket and voltage regulator at this time. The voltage regulator is the square thing shown in the picture to the left. The picture also shows the newly wound stator coils with the addition of a yellow wire that is common on most dirt bikes.
Acerbis HP headlight in blue
ttrblue.jpg (13.54 KiB) Viewed 5797 times
I wanted the plastic of the new headlight to match the blue plastic of the original Yamaha plastic color. After some checking around, I purchased the Acerbis HP headlight and taillight assembly. I went to a boating supply store and purchased marine-grade wire, heat-shrink tubing, connectors, and a 2-1/2" stainless steel bolt, washers and locknut for mounting the voltage regulator. I bolted the voltage regulator to an existing hole on the right-side of the frame under the gas tank, as you can see in the picture to the left. I removed the CDI unit to facilitate easy installation. I made sure all ground connections were on clean bare metal. I used the left side mounting of the ignition coil because it already had ground wires going to it from the factory.
Wiring on frame under gas tank
wiring.jpg (19.14 KiB) Viewed 5797 times
I wired four female power connectors into a red wire to plug the high-beam, low-beam, taillight, and brake lights into (all separately). I soldered all wires into the connectors for durability. The red wire just connects to the yellow wire coming from the newly wound stator. I used plastic zip-ties to hold everything in place, just like factory.

Notice the two forward-most red wire connectors in the picture to the left. I have intentionally left these where they are accessible when the bike is reassembled. This allows separate connection of the high and low beams in the headlight while I figure out what works best (i.e. high beam, low beam or both).
Acerbis HP headlight on TT-R125L
headlight.jpg (8.86 KiB) Viewed 5797 times
The Acerbis HP headlight kit requires you to make your own wiring plug for the back of the headlight, but they do give you the metal connectors to solder or crimp on the wires and a plastic plug to snap them into. Again, I soldered all connections for durability. I also used a piece of heat-shrink tubing to group the 3 wires and run them down under the gas tank. [You may want to find other tubing to use for a loom as heat shrink may eventually shrink down over time from the heat rising up from the motor.] This helps reduce stress on the wires when turning. If you use heat-shrink tubing, do not heat and shrink it because it will be too rigid.

The Acerbis HP headlight is smaller than I expected but a good size for the TT-R125L. It cost a bit more than others but it is DOT approved and can use standard light bulbs (Sylvania 9003 or equivalent) found at places like Wal-Mart for $7.00 and available in several wattages. Note: Baja Designs will try to sell you the same bulbs for twice as much money. I ended up putting in a Sylvania Blue-White Halogen 65/45-watt bulb. I am trying it with both high and low beams wired up to run together (Baja Designs said this was fine) for an incredible 110 watts [estimated] of woods-illuminating power! Update, both beams on is the best configuration.
Zip-tie holding headlight back
zip-tie.jpg (10.96 KiB) Viewed 5797 times
It was a real chore mounting the Acerbis HP headlight so it would not interfere with the front brake line. I also had to trim some plastic from the headlight bezel to keep it from hitting against the gas tank shrouds in tight turns. The modification shown in the picture to the left was required to keep the headlight bezel from touching the brake line. I just drilled a hole in the headlight bezel and zip-tied it to the handlebar so it would not contact with the brake line. The choke is a little harder to reach but doable. [An alternate to this might be to find a headlight with a fascia that does not interfere with the brake line as much. It is not that critical if the brake line touches or rubs slightly on the headlight fascia. You would also be able to run the all-important handlebar crossbar pad.]
Notch in headlight bezel to clear shroud
cutout.jpg (6.12 KiB) Viewed 5797 times
The picture to the right is a close-up of the headlight fairing showing the corner I had to cut away with a Dremel tool (on each side) to keep the headlight fairing from hitting the shrouds in tight turns. Not that apparent in this picture but on 3rd picture from top of this page is clear vinyl tubing around each fork tube that Baja Designs sold me to make the Acerbis headlight fit the small TT-R forks better. The rubber straps that hold the headlight to the forks were optional. I used two zip-ties, one around each fork, to aim the headlight downward and to position it left-to-right. Each zip-tie went through a hole in the middle of the plastic rim under the headlight lens. [Some headlights have adjustable beams so this mod may not apply.]
Acerbis DOT approved taillight assembly
rearlght.jpg (7.88 KiB) Viewed 5797 times
Taillight: I opted to use the Acerbis DOT approved taillight assembly shown in the picture to the left. It is has a large mounting area for a license plate and the taillight puts out a small amount of white light underneath to illuminate a license plate. The Acerbis taillight assembly came with stainless steel hex-head (Allen) hardware. [The way this taillight assembly mounts to the rear fender actually strengthens it. If you do not go with this particular taillight, try to find something similar that will help to strengthen the rear fender. The TT-R rear fender (and most others) will not support a taillight assembly if its just hanging off the end of the fender.]
Acerbis HP headlight at idle and revved up
lights.jpg (11.85 KiB) Viewed 5797 times
The headlight on the right in the picture to the right shows that there is not a lot of power when the engine is at idle, but who rides their dirt bike with the engine at idle? When the engine is revved up just a little bit, the headlight on the left in the picture shows what the new Acerbis HP headlight looks like with my newly wound stator. Again, this is with both high beam and low beam wired together.

Total cost of project was $330 and breaks down as follows: Stator rewind $135, OEM left engine cover gasket $5, Acerbis HP headlight assembly $90, Extra light bulbs (2) $15, Headlight mounting straps (4) $20, Acerbis taillight assembly $40, Rear brake light switch & bracket $15, and marine grade wire & hardware $10.

I could have spent less by not getting the rear brake light switch. I could have spent more and got a Hi-Lo or On-Off switch for the headlight too. It all depends on what you want to do. If you want the bike totally street legal, you will probably need these parts, otherwise I would say they are optional. I also did not go with a horn or turn signals and I hear a horn requires a real motorcycle battery to actually sound right. I was just trying to keep my modification simple. Baja Designs' official TT-R125L dual-sport conversion kit with turn signals, horn, switches, etc. runs $400 plus another $100 for the stator rewind.

Credits: TTR125 Lights Install article written and submitted by Tom Rogers. Edited and published by

Post Reply