ALLEN MILLYARD
Our Allen is talking about sorting the zorsts and fixing leaky things!
Iwas conscious that I needed to send four used header pipes off to ACF Howell for chrome plating, but before I could send them I needed to fit the exhaust system to the bike and make the new collector boxes to join the six headers to the four original silencers.
I was hoping to finish my Z1B Super Six by the time the current coronavirus lockdown rules were relaxed to allow motorcycles to be ridden for leisure. My friend Neil is getting on well painting the tank, side-panels and rear fin in Z1B dark candy red and they should be ready by the end of March.
When I made my first Z1 Super Six I had bought two sets of exhausts from Z1-parts in California so that I could use two of the headers from the second set to make the six-into-four system. I planned to use the second set of exhausts on my second Super Six, but would be short of four header pipes. Luckily, the Z1B donor bike had its original exhaust system and although mostly rusted out, the headers were in fair condition and would rechrome nicely. I cut off the four header pipes, trimmed them to length and cleaned out as much of the carbon from inside the pipes as possible.
ACF Howell will rechrome exhausts but they have to be sure all carbon is removed; this will add time to the chroming process while its being cleaned out, so the more I could remove the better. I temporarily
fitted the four old headers to the engine two each side on the outer four exhaust ports. I then cut off the two remaining new header pipes and fitted them in the centre and lightly tightened all 12 clamping nuts. I could then position the headers so that they line up, three each side of the bike. I had already trimmed them down in length so that when the four silencers were bolted in place there was a 150mm gap for a pair of three-into-two collectors.
I made the collectors from stainless steel tube that was a sliding fit over the headers, first cutting 10 pieces of the tube about 30mm long. Five tubes for each collector were arranged on the bench to match up with the spacing of three headers and a pair of silencers, and then welded together. Finally a piece of stainless steel sheet was cut out and formed to fit around the tubes and welded in place to make the two collectors. The collectors were then cleaned up with a file and abrasive paper and buffed to a shine.
Each collector was then slid over the three headers each side and positioned so that the two silencers would engage with the collector outlets. With everything in place and checked for alignment, I tack welded the collectors to the silencers, then gently pulled them off of the header pipes to finish off the welding on the bench. When the welds were complete I painted over the welded area with high temperature silver paint just like Kawasaki did on the original exhaust system.
I then fitted the original stainless steel wrap-around covers to cover the silver painted weld area again just like on the original Z1. With the exhaust system test fitted, I could finally remove the four outer header pipes and send them up to ACF Howell for chrome plating. So, that’s it for now, there is nothing more to do on the bike until I get the header pipes and paintwork back.
As work had ground to a halt on my Super Six, I decided to check over a few bikes ready for the summer, and one that had sat idle for a couple of years was my 1983 Kawasaki KDX200A. I restored this bike 15 years ago and use it most years for trail riding and a few enduros. It’s amazingly good off-road, being light and nimble, and it also has a proper seat that is comfy when riding on the road. The engine started easily and it seemed to run okay, but I noticed it was hanging on the throttle and not returning to idle like it usually did. I thought maybe it was a sticky slide in the carb or a damaged throttle cable but on further investigation all was good.
At the next point I needed to go out I took the KDX so I could test it and it certainly went okay, apart from the erratic idle and quite a lot of smoke. I suspected it may have leaking crank seals which can cause an erratic idle and oil to be sucked into the engine from the clutch casing, causing the excessive smoke.
I removed the plastic magneto cover
from the left-hand side of the engine and there was a strong smell of petrol and a fair amount of oil that dripped out on to the floor. The crank bearings felt smooth when I rotated the flywheel and I couldn’t feel any play, but the crankshaft oil seal was definitely leaking. I rebuilt the engine in 2010 with a load of new old stock parts including crankshaft seals, but over time the rubber seals can harden and then need replacing. It is not possible to replace the seals by pulling them out of the crankcases in situ like it is on some engines because the seals press into the crankcases from the inside up against a shoulder.
So the engine has to be removed and the crankcases split to change the seals. While the engine is apart it’s a good time to check the big-end, main bearings, gearbox internals, clutch plates, piston and Nikasil coated cylinder. The first thing I did was remove the tank, seat, exhaust and carb, and then drain the oil from the engine. The engine is small for its capacity and really light, and after removing the engine bolts, disconnecting the chain and magneto wires, it lifted out easily.
The engine was then stripped down and all parts cleaned, and I was pleased to see no significant wear or damage. The bore was perfect and the piston was well within its wear limit, as were the rings. I decided to replace the main bearings because I had to remove them to change the seals and it’s a good idea to fit new ones while the engine is apart. I ordered a pair of SKF bearings from online supplier Simply Bearings; they sell all kinds of bearings, seals and general engineering equipment, and provide a fast delivery service. I managed to buy a pair of genuine Kawasaki crankshaft oil seals from Corby
Kawasaki who still have a few early parts in stock. When the parts arrive I will reassemble the engine and hopefully the bike will run nicely again.