The eighth instalment of my first cafe racer project on a budget.
Problem Solving! leaking carburettors, mis-firing, spongy brakes.
Progress has been slow over the last two months due to holiday and other competing projects and also trying to resolve some build problems which I had not anticipated.
In my last update I refitted the carburettors and got the engine running after a fashion and my next job was to fit a Dynojet stage-3 kit (£120) and a carb rebuild kit (£60). It soon became apparent that the float valves were not sealing properly and on further investigation I discovered that the valve seats were badly pitted. I sought expert opinion and also checked out some YouTube videos. I attempted to improve the seats, which are not removable, using cotton buds dipped in a light abrasive paste and fitted in an electric drill. This improved the seating but there was one carb in particular that I just could not get good enough. Offers of help were gratefully accepted but this problem could not easily be solved. My next thought was to try and source a replacement set of carbs and as luck would have it I quickly found and purchased a set for £102 including shipping. I knew these were not identical to the originals and in fact turned out to be 2mm larger inlet diameter (Keihin CVK 34 vs 32 mm originals). I still haven't discovered the exact bike model they came from, opinions suggest Suzuki GS or GSX and more specifically a GSX 750 from 1979 to 1986.
The replacement Keihin CVK 34 carbs in front of the original set
Anyway they fitted into the original rubber inlets manifolds and I had the engine running on the first day. However, changing the carbs also meant that the Dynojet kit and most of the rebuild kit didn't match. The mixture screw on carb three is directly above the cam chain tensioner so not easy to adjust when in situ. To get round this I soldered small brass split pins to the top of each mixture screw and bent them at 90 degrees to create a simple adjuster.
I have been using a small temporary fuel can to test the engine but it was not running smoothly on all 4 cylinders. I tested for a spark on cylinder 1 and there was no spark at all although it had been firing intermittently. Cylinder 2 and 4 were ok but cylinder 3 was not firing either. This pointed to a fault with the right-hand coil and it turned out to be a basic but hidden faulty connection. One side of the low voltage circuit was not pushed onto the spade correctly. The spade on the coil was sitting between the plastic cover and the connector itself and was quickly resolved once identified.
Whilst the inside of the Z1000 fuel tank looked reasonably clean through the filler cap I wanted to give the petcock a thorough clean. Just as well as the amount of dirt I removed, including a dead fly and scaly flakes in the outlet pipe, would have resulted in a very short journey before the first breakdown.
With the carb swap, electrical issue, mixture adjusted and fuel delivery sorted out the bike is now idling smoothly and responds quickly to throttle action. I have changed my order for a pull only throttle cable to a push/pull type as required for my new carb setup.
I fabricated the number plate side mount from a piece of aluminium and I came up with a personal design for the number plate itself. A local sign maker produced exactly what I was hoping for and I also had an idea to create side plates for race numbers. Being a member of the local 66 MCC the number was already decided. Next I made a bracket for the Delkevic exhaust system as the one which came with the kit was designed to attach to part of the frame which is now in the bin!
Seat is only loosely placed for the photo
Having soaked the brake callipers in diesel for a couple of days the cleaning process could begin. The old paint came off fairly easily and my friend Colin removed the old pistons using a grease gun attached to a grease nipple that had been temporarily screwed into the calliper in place of the bleed nipple. The front and rear callipers are interchangeable on the Z750 but and I used a spare front calliper to replace the missing rear calliper. What I hadn't noticed was the position of the brake line and bleed nipple were reversed because I had been given the front right instead of front left so I had to use a longer brake hose to reach.
My first attempt at adding a voiceover!
With everything tightened up and the rear brake master cylinder charged with DOT 4 fluid it took me less than 15 minutes to bleed the brake. The front brakes were a completely different story! I have tried nearly every method known to man and woman to bleed the front brakes and even as I'm writing this blog the brake is very spongy and definitely not safe to ride. Today I enquired about buying a vacuum pump but at £50 for a once only process (hopefully), I can't yet justify this expenditure. Especially as I've seen the vacuum advertised on eBay for around £14. Stop Press...I've just ordered this one!
Fingers crossed that the brakes will be fully bled very soon!
If all goes to plan part 9 of my video blog will be the final stage of the build ready for the road and later part 10 will be out and about riding my Z750 creation. Thanks for following.