TYGA GP 500 (Street version)

TYGA GP 500 Racer (Street Version)

August 2002

Due to popular demand from customers who wanted their GP replica for the street and wanted lights, we decided to modify the NSR500 Replica to make it street ridable.

First job was to make a headlight that wouldn't spoil the looks of the Rossi replica. Cutting holes in the upper was out of the question, as it would have meant removal of some of the famous # 46. Using the duct was the obvious choice, but to do so in a way that kept the duct looking like a ram air duct was the tricky bit. After much work, we settled on a pair of projector beam lights, which are held in a lightweight box to prevent light being reflected inside the cowling.

The box is wrapped in black tights (panty hose for those in the US). Don't laugh!! They weren't mine! When the light box was secured in the air duct of the cowling, the black tights are very inconspicuous and hide the lights behind them. When the lights are turned on, the light shines through the tights and the oncoming traffic can see the bike approaching. On our version, the projector beams were dim to start with and the beam projected is not enough to see when riding on unlit roads. Purely for urban or daytime use!

The headlight wouldn't be much use without a lighting loom. We decided to leave the HRC racing loom intact and instead made a separate lighting loom with a master switch, which switches on both looms. We didn't have a key on our loom so the switch is hidden for security and an MC28 top triple clamp fitted for clean looks. Incidentally, those wishing to hide their ignition switch on the MC21 can relocate it to the helmet lock position on the left frame mount and fit an MC28 upper triple clamp instead of the stock item.

So we now have the headlight and light wiring. After that the taillight was easy. We decided to remove the entire undertray on the Rossi rep and made a one off custom aluminium subframe saving around 2 kgs. To this we cut out of corrugated plastic a very lightweight undertray, which slips in under the seat cowl and protects the electrics form water and stones flying up into the seat cowl. We then simply screwed a TYGA tail light in position and it is very tucked away but very visible when turned on.

No street bike is complete without mirrors. We considered using the stock ones with the stock mirror stay and they will fit. However, we prefer the GP upper stay on the GP cowling and decided to source a more suitable style that secure directly to the upper cowling. We were worried that both visibility and vibration would be issues, but seeing behind is no worse (or better) than stock and the mirrors only vibrate on tick over so that problem is solved.

Finally, the airbox (or lack of) needed attention. Riding open carbs is fine if you are racing or willing to change cranks every 500kms. However, it was spoiling the enjoyment of riding the bike when all you could think of was all the grit and bugs getting sucked in the engine. An airbox was modified to give full airflow. The lid was cut down so only the rim remained and the central division in the airbox cut out to maximise air charge. The tights came to the rescue again! We hacked the legs off the tights, (the waist part being used for the headlight) and stretched one leg over the remaining part of the lid. This gave us double thickness and then we screwed the rim to the airbox carefully without laddering them! The carbs were rejetted to suit and Matt got the jetting so that the bike was actually as fast or faster than before the air box was fitted. The only negative aspect being the increased induction roar, but it isn't offensive, well, not to us!

Other things that may get done later, are a speedo cable, back lighting for the instruments and turn signals. However, this bike is not really for touring or long night trips, so we'll probably leave it as it is. On the other hand, knowing us, I doubt it? Paul

List of the products used below.