Resilient Ride: KAWASAKI ZRX1200/R Custom by TG NAKAGAWA
TG NAKAGAWA's ZRX1200/R
This ZRX1200R was built by TG Nakagawa about 10 years ago and recently came in for an engine overhaul. However, since there have been some changes in the environment and technology since it was originally customized, the overhaul also included some updates.
If we take a look at the original customization, we'll see that the bike was a full-custom with everything from the engine to the chassis worked on. Since the owner has racing experience, the transmission was converted from a 5-speed to a 6-speed using modified stock parts from a ZZR1200, and since the ZZR has the same displacement as the ZRX but uses high-compression pistons, those were also specially modified and installed. The kind of engine tuning that TG Nakagawa is known for, such as head surface grinding, port polishing, and crankshaft balancing, was also done to create a high-power unit with rear wheel output of over 170 PS. At the same time, the frame was reinforced, the detachable right down tube was modified, and the front and rear suspensions were tuned, making the machine as a whole a flawless package.
The owner had been enjoying these specifications for the past 10 years when he decided to bring it in for an overhaul. This time, the updates included changing the cowl to a frame mount and equipping new front brake/clutch master cylinders (GALE SPEED Radial). The engine specs remained the same, but TG Nakagawa's proprietary R-Shot#M surface treatment was applied to almost all of the internal parts. Mr. Nakagawa told us that he recommends applying R-Shot#M treatment to all the internal sliding parts of the engine, but if he had to give priority to a few places, where would those be?
"First of all, the pistons and piston pins. Then the transmission (shafts and gears), the shift area (drums/forks), and the crank metal. I would recommend these five parts, and if possible, also the valve guides and cam holders. The five places I first mentioned are also chosen because of the discontinuation of stock parts. Since these parts are hard to obtain, in other words, it is difficult to replace them easily, you want the replacement span to be as long as possible. If the surface is stronger and smoother, the possibility of breakage is reduced, and the degree and speed of wear can be mitigated, which is why this treatment is recommended. For the valve guides, it doesn't change the power of the engine, but they don't wear out as fast and you can eliminate rattling of the valve stem and reduce the frequency of valve and guide replacement. It also reduces the cost by eliminating the need for making new guides. Treatment of the cam holder (cap side) also noticeably smoothes cam rotation. For the counterpart cam side, we use journal wrapping,” says Nakagawa.
Although the number of parts may seem like a lot, when you come in for an overhaul every 40,000 to 50,000 km, the engine just needs to be opened to check the condition of the parts, and replacement work as well as the cost of the parts themselves can be reduced. It also has the added benefit of making the ride smoother. This machine has taken advantage of these benefits to cope with the increase in the number of discontinued stock parts within these past 10 years. The pistons were also checked and found to be in the usable range, so R-Shot#M treatment was applied to them, giving the owner peace of mind for the future.
Handle
With the change to a frame mount, the stock cowl was also replaced. The gauges were also changed to a one-off panel made by TG Nakagawa with a Stack ST700 meter and SP Takegawa fuel gauge. The handlebar was replaced with an EFFEX, and the left and right master cylinders were also upgraded to GALE SPEED VRC, for better control and touch.
Bodyworks
The 2001 A1 stock color, Firecracker Red / Ebony, is still intact and pristine, so the fuel tank remains stock, while the fuel cock has been changed to a Pingel to ensure enough flow to match the carburetor change.
The seat is TGN's original complete seat and inside it is TGN's original HIR ignition unit that can be used for creating, saving, and switching engine maps.
Engine
The engine is a ZRX1200R with pistons from a ZZR1200, which has the same displacement and bore as the ZRX1200R, but higher compression (10.1:1/10.6:1 compared to stock), and the transmission has been changed from a 5 to a 6-speed, also from a ZZR1200. Head surface grinding, port polishing, edge treatment, crank dynamic balancing, etc. were all performed to achieve 170 PS. In this overhaul, almost all internal parts were treated with TG Nakagawa's original R-Shot#M surface treatment. The pistons were measured to be within the usable range, so R-Shot#M was applied to them as well. The pistons are now smoother and more durable, so they should last for a long time to come.
The carburetor is an FCR φ41mm. The frame has been reinforced in various parts, including at the back of the main loop (triangular shaped part) behind the carburetor (left side in the photo).
Chassis
The steps are MAVERICK, the hydraulic clutch kit is by WHEELIE, and the drive chain is an RK 520XXW.
The forks are Ohlins upright with a WHEELIE 28mm offset (same value as stock) stem. The front brakes are a combination of Brembo Racing CNC 4P axial calipers and SUNSTAR Works Expand discs.
The rear brakes use a Brembo CNC 2P caliper + GALFER wave disc. The exhaust system is a Nojima SC Full Titanium.
The swingarm is a WHEELIE and the Ohlins rear shock is a Grand Twin/KA417, replacing the previous fully adjustable shock. The wheels are MAGTAN JB3 with 3.50-17/6.00-17 sizes, making the rear one size wider than stock.
Gallery
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Specifications
About TG NAKAGAWA
TG NAKAGAWA is a cusom builder that deals GPZ and ZRX dedicatedly. They deal many complete cusotom and sell many dedicated parts. A rider hoping for further potential up to one's favorite vehicle is unmissable.
Original Source of this Article
Heritage & Legends


editor
Hakuyo
A foreigner who rides in Japan, Japanese call this "Gaijin Rider". Third year in the Webike global team. He feels and shares the real bike life in Japan then presents you how interesting Japanese customs are.