Odd job man!
With lockdown in full swing, Allen's on with his Zed Super Six and also doing some odd jobs!
It's been a strange few weeks not being able to ride my bikes or go to bike meets and shows, and especially not being able to test ride my newly completed Kawasaki Zl 1396cc Super Six. I had one last job to do on it before its first road test and that was to fit some better fuel hose that was ethanol resistant. The original fuel hose that I bought online had gone hard in a matter of weeks after contact with petrol, and also as a precaution I wanted to fit a pair of inline filters. The standard petrol tap filter is made from quite coarse brass gauze and can let some sediment pass through. For those of you who follow my social media posts you will have seen the finished Z1 Super Six and also may have heard the engine running, but I've been resisting the temptation to take it out for a test ride while the current lockdown is in force. In the meantime I have started to make a new six cylinder Z1 engine, and this one will be 1522cc utilising the 70mm bore 1015cc Zl000 barrels. I'm planning to complete this bike in slower time as an exact copy of my first Super Six, but maybe in a ZLA colour. I've been catching up on my routine bike maintenance and keeping the batteries on a trickle charge rota. The last time I rode my Honda SSLO0 V-twin I noticed that it had a problem with 4th gear: it would intermittently click and had been like this for a while, so this was an ideal time to take the engine out and strip it down for investigation. I built this SSLO0 in 2012 and it has done around 800 miles; being a small bike I generally only use it for local trips. With the engine apart the problem was immediately obvious: the 4th gear on the lay-shaft and final drive shaft each had a tooth missing! I was amazed it still worked at all and didn't make more noise. This was a common problem on the SS50 gearbox gears, especially the 5-speed versions that have thinner gears. After a quick rummage in my shed I found a pair of spare gears in good condition and they fitted perfectly. With the engine back together and running nicely, the next job on my list was to sort
out my son Sam's 1975 Honda Xll 75 engine. Well, it's actually a bit bigger because several years ago I bored out the cylinder casting and fitted a modified 70mm liner from a Kawasaki Zl000 and a VFR750 piston bringing it up to 210cc. The bike had been running fine, and Sam often uses the XL as his everyday commuter bike as well as for trail riding. Sam is a proficient motocross rider, so to say it gets gentle treatment off-road is probably untrue. The engine had gradually lost power over time and was burning a lot of oil. Sam had previously taken the engine out and left it with me so I took the head off to investigate the problem. At first everything looked ok, the piston didn't rock too much in the bore and there was no sign of oil seeping down the valve stems, so the next thing to do was remove the barrel and piston. With the barrel removed the bore looked to be in excellent condition with no significant wear or lip at the top, the piston also looked in good condition so I removed the piston rings to check the end gaps. The two compression rings had huge gaps over 1mm, but when I checked the three-piece oil ring the two scraper rings just fell down the bore! I had never seen this before and the end gaps were also in excess of 1mm. This was quite possibly the cause of the loss of power and excessive oil consumption. I started to think that maybe the piston rings were a bit thin and designed to run in a VFR750 water-cooled engine where the piston temperature can be more closely controlled. I looked under the crown of the piston and found a layer of burnt black oil deposits, indicating that the piston had been running quite hot in this single cylinder air-cooled XL engine.
New VFR piston rings are expensive and usually bought in sets of four so I thought I would see what I had in the shed that I could use to get this engine running again at minimal cost. Then I remembered that I had two spare pistons from my latest Zl Super Six engine that were complete with rings. These pistons were 70mm diameter, which would be perfect for the VFR piston, but the rings were significantly thicker and wouldn't fit the grooves. This was easily rectified by setting up the VFR piston in my lathe and re-machining the grooves a bit wider. I first checked the rings in the XL barrel and they fitted nicely with a minimal end gap so they would be perfect once they fitted the VFR piston. With the ring grooves machined the Zl000 piston rings now fitted on to the Honda VFR 750 piston, so I placed it in the XL barrel and I could feel the difference immediately as the piston rings were actually rubbing on the bore. With the piston rings sorted I lightly honed the bore with my four-stone adjustable cylinder hone, to produce a nice crosshatched finish which would aid running in the new piston rings. I then made a new base gasket from 0.8mm thick Flexoid gasket paper. I had previously made the cylinder head gasket from 1.2mm thick pure copper sheet so it just needed cleaning with steel wool and re-annealing by heating cherry red with my Map Gas blowtorch and then quenching in cold water. This makes the copper gasket soft and malleable, making it perfect for re-use, but I generally put a smear of Permatex Ultra Grey gasket sealant around the cam-chain tunnel and oil galleries to help prevent any oil leaks. With the top-end reassembled I set the ignition timing using a battery and bulb. This is an easy method to use on points ignition bikes. All you have to do is connect the wire from the points to the negative side of a battery, then connect a bulb between the positive side of the battery and the engine cases. I usually undo a cover screw and pinch the wire under the head of the screw. Then the bulb will light up when the points are closed and go out when the points open. This makes it easy to adjust the points so that the timing marks align at the F (fire) pointer on the flywheel just as the Iight bulb goes out. With the timing set, the engine was ready for Sam to refit into his Xll 75. He is giving the bike a light rolling restoration while we're in lockdown, but will be out on the trails again soon.