REBUILDING A KAWASAKI GPZ1100 | PART 2

Date 21.7.2016

Presented by
  • Motorcycle Trader

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In Part One of ‘Rebuilding a Kawasaki GPz1100’, we left our intrepid team with plenty of work required to get it rolling. Here’s what happened next…

…A new swingarm was sourced from the US. Trying to get one here wasn’t easy as not a lot of ZZR1200s were sold compared with the number in the US. It was about a third of the cost (with postage) of a locally available one and it was in excellent condition. It got cleaned, checked, painted silver on the inner surfaces and polished on the outer surfaces – job done.

The old swingarm was used to check the clearance on the frame and the frame bracing turned out to be mighty tight. Dale had to resort to a rather agricultural method to restore order to that region. Another solution – well done Mister Dale.

The downtube needed attention on the alternator side of the engine as there was a large dent in the tubing. It appears a previous owner had belted the frame flat to fit an exhaust. Hmmm.

The swingarm clearance issue was fixed and the rear shock got tested and came up okay. I’d sourced a GSX-R1400 unit which fitted but needed more room. The battery box needed to be smaller as well so we could run a lithium-ion battery.

Kawasaki GPZ1100 P2 Kawasaki GPZ1100 P2

The downtube was fixed, the battery box was fixed and a nice little collection of parts was found locally in Melbourne, which included a better tank gauge, seat, fairing, side covers and battery box. The fairing was in excellent shape, not like the original.

The new seat will be used as well. The poor old original ducktail had holes drilled in it and cracks. Dale had a few goes at reviving it, using every trick at his disposal including an ABS hot stapling machine for repairing plastics, but to no avail. The old ducktail was turned off life support and is now in the great parts collection bin. The new one is ace. We are keeping it simple so the grabrail is gone. The lines of the ducktail to seat are really much improved with it gone. The seat will be upholstered to sit flush with the ducktail and the front of the seat needs to be much flatter so I can move around on it.

BLOOD-BOILER

The top triple-clamp from the ZX-6R had been modified to suit flat ’bars. As the triple clamp spindle diameter is greater than the hole in the ZX-6R unit, a previous owner had filed the hole bigger to make it fit. It’s finding things like this that make my blood run cold – then hot – then I have the steam from the ears. WTF? Another top triple-clamp was sourced, cleaned up and made ready for the upright ’bar conversion.

The engine cases were bead-blasted and came back looking amazing. Every detail from the casting is revealed so no damage at all is done to the material and its surfaces.

Now it’s ready for the Dale’s special paint treatment. Having seen his Firecracker Red 1983 GPz1100 (see Part 1) and the engine paint on that, I knew it was going to be excellent. The cases got their coating of black, along with the frame. It was all ready to get assembled.

Kawasaki GPZ1100 P2

I was still sourcing parts for the transmission and engine and it was going amazingly well – just present at Peter Stevens and give the part numbers. Easy. The head was still progressing nicely. The porting was critiqued and improved on to actually work. The barrels were line-bored and then were ready for paint. The cams were assessed and approved to suit the engine and the state of tune we were looking for

With the head in the hands of a maestro like Mr Trease, and him overseeing the most important aspects of the design of performance, I’m secure in knowing that each part of the machine will be working at its best with all the other parts, each part complementing the other to produce the overall and predicted improvement, as opposed to the parts working against each other. This process of refinement, and improvement is detailed and painstaking work and requires an enormous body of knowledge and expertise.

This isn’t an exercise of ‘big-it is’. When you just make everything bigger, it’s got to be better, right? We’ve avoided big capacity, high compression, too much fuel from too big a carb size, choking, ineffective flow characteristics of fuel delivery, combustion compromised by inappropriate cam profiling and a whole range of other popular mistakes. We aren’t going down that road, thanks.

The GPz1100 wasn’t a noted stump puller and delivered its power mid-range from where it kept building. We are enhancing and refining that, not changing the characteristics of the power delivery. The last thing I need is for it to be delivering all its power in a narrow range. If I wanted that, I would have built an RG500 with chambers.

TIRING WIRING

The frame was all ready for some bits to be attached to it. New bearings were bought for the wheels and rear sprocket housing and they were fitted. I’m glad I have nothing to do with the nightmare of dealing with the wiring. Ideally, a completely new wiring loom is needed. The existing loom has wiring that is dried and failing so it has to go.

Luckily, Dale has a lot of experience in huge wiring jobs including cars and bikes. Try making a full wiring loom for a Corvette left-hand-drive conversion – oh, and doing the conversion itself. Fries my brains.

So the wiring was starting to be sorted out. Luckily, we had almost everything working before it was torn to pieces so we knew the parts worked. The wheels went into the frame and the forks were placed to help us figure out the fairing issues.

Kawasaki GPZ1100 P2

The swingarm in and shocker mounted. The brake discs have been painted and treated to new bolts for the rotors. The front calipers got fresh pads. Given the weight of this thing (now often referred to as ‘The Green Machine’), as much braking as I could get would really help. I went looking for Brembo carbon ceramic pads and found some. They were excellent so I’ll be keeping them and recommending them.

On the weight issue, the Green Machine has been very responsible and stuck with the Jenny Craig program. It’s lost the stock pipes, centrestand, footpegs, swingarm and the stock alloy wheels. OMG, how heavy are they!

The tank, fairing, side covers and ducktail all got primed for paint, and I finally confronted the decision about what colour the stripes would be. I looked at lots of other custom GPz1100s and I hate those dumb stripes on the sides of the front fairing.

Kawasaki GPZ1100 P2

The black section on the tank really helps to define the tank much better: there’s a nice curve on the sides along the top side of the tank and the stripes follow that. This is carried all the way down to the black contour line at the bottom of the tank. I always thought the original model seemed really long and the paint scheme worked to magnify that. I think the new paint scheme enhances the shapes of the ducktail, side covers, tank and fairing much better.

We went with the original Kawasaki Racing US paint from the Eddie Lawson KZ1100: white stripe above the royal blue on the Kwaka green. Dale has gone into expert paint-mixer mode to make his colours. They have a very fine metallic through them all, also having a coloured sparkle that only shows in the sun or up close – very subtle, very classy. The two stripes are normally divided by a gold pinstripe, so that needs to be done.

Kawasaki GPZ1100 P2 Kawasaki GPZ1100 P2

The engine in stock form has rubber mounts and these soon turn into black marshmallows, letting the engine slop about. A much better solution is to make solid engine mounts. Off to CAPRAL and some alloy to feed the lathe. It’s an easy and very practical solution.

With the engine parts all sorted out, we were just waiting for the head to be completed and finding the last bits when we discovered the transmission bearing supplied was incorrect, so we had to find a new shaft bearing. It’s an obsolete part so it was off to BSC in Clayton. Almost unbelievably, one was located just hours after making the call. That’s great service. It’s genuine and made in Japan by the same manufacturer with the same clip retainer and the same bearing clearance specs. What a relief.

Stay tuned for Part 3 when, two engine builds later, we wonder will it run?

Article by Duncan Aitken-Bain