Frequently Asked Questions about the R21
Q. What relays will I need to use the R21 on my Airhead?
None! The R21 eliminates the starter, headlight, flasher, and horn relays.
Q. Will I need to buy additional special items to work with the R21?
No, only if you intend customizing the look and feel of your Airhead.
Q. My main wire harness is beyond repair on my Airhead. Is the R21 a viable option instead of replacing the chassis harness?
Yes! You can forget about replacing the chassis harness and the associated dreaded work inside the headlight bucket. The R21 will allow you to maintain the original (stock) appearance of your Airhead.
Q. Do I need to do anything special to run LED turn signals like adding resistors, with the R21?
No. The R21 does not need to detect the bulb resistance to flash your turn signals properly. Traditional bulbs or LED replacement work perfectly, the R21 knows what to do!
Q. I am electrically illiterate, can I still install the R21 myself?
Yes, The R21 comes with an easy-to-follow installation guide that can be viewed on your phone whilst installing the R21. If you get hung up on anything, a dedicated support email channel is available for prompt accurate support from the designers and electrical engineers at
Q. Is the R21 the same as the other systems offered by NWT?
No, The R21 is specifically designed for, and incorporates unique features for BMW Airheads.
Q. I am building a custom BMW Airhead, Will the R21 work for me?
Most certainly! You can go from totally original (stock) to completely custom, and any variation in between.
Q. Do I need to buy those fancy momentary button switches?
No! You can install most any switches, however on BMW Airheads the handlebar controls are integrated. The switches link into the throttle tube, and the levers, etc. If you change the switches, you need to change the brake lever, clutch lever, and throttle tube.
Q. Can I use a lithium battery with the R21?
Yes, the R21 has sophisticated circuitry to including a built-in voltage regulator to protect itself from voltage spikes.
Q. How long does it take to wire an R21?
Typically, the installation process can be done in a few hours! We want you riding your bike, not working on it in the garage on a never-ending project!
Q. Why should I choose the R21 over other similar products on the market?
The R21 readily available for prompt shipping and is reasonably priced. The R21 is fully supported with sophisticated technical assistance. A great problem solver in that it replaces the sometimes unobtainable chassis harness and can be fitted with stock or custom switches, lights and other gadgets.
Q. Can I use an aftermarket gauge with the R21?
Yes, you can use the stock, or any aftermarket gauge available.
Q. Can I connect my phone to the R21?
No, Keep the screen time for the bathroom. We believe in ridding with wind in your face, rather than playing with your phone.
Q. Is there a wireless fab option for the R21?
Sorry, the wireless
Key Fob option is a parasitic draw on your bikes electrical system, as it is always on and hunting for a signal. If you use a key fob system, you need to keep your bike plugged into a battery tender or your battery will be dead in short order. Instead, you can use any of the factory stock key switches, or the aftermarket KEY-SW-R21 from NWT Cycletronic.
Q. Do I need to know how to solder to install an R21?
No. The entire installation can be accomplished by crimping wires together.
Q. Are there any special tools I need to install the R21?
Basic electrical tools are all that is required such as a wire cutter, stripper and crimper. You could also use heat shrink tubing and a heat gun for a clean installation. Soldering connections is not required, although never a bad thing to do.
Q. Will I need to purchase additional wire?
Possibly, for the output side of the R21 you may need 8awg to the battery positive and ground, 16awg to the key switch, 18awg to the horn, headlight etc. and 20awg or smaller for LED lights. All of the input side is included and the fine wire gauge wire is all that is needed.
Q. Where do I mount the R21?
You can secure the R21 in almost any location. On Airheads, under the tank is a great location and can also be mounted where the original starter relay was located on /5, /6, or /7 models. On later models you can mount the R21 on the back of the center frame where many of the original relay’s were mounted. On a custom installations, builders often make a pan for under the seat or in the tail section for this purpose. You can mount the R21 anywhere but remember that heat kills electronics, so keep the R21 away from heat sources where possible.
Q. Do I need to worry about moisture, water, or vibrations with the R21?
No, The R21 is all solid state. It has no moving parts and is completely shock, and water proof.
Q. Will the R21 work with the other EnDuraLast electrical products?
Yes, The R21 works great with the full line of EnDuraLast starting, charging, and ignition systems offered.
Q. Will the R21 work on older (pre-1970) 6v Airheads?
No, a system for all 6v Airhead models is currently being designed.
Q. Will the R21 work on the stock momentary Airhead switches found on GS's installed in 1991 on?
No, The switch's function completely different on these model's and is not compatible with the stock R21. For these switches you will want to order the R21-MS
version that is programed properly.