Sunday, 27 March 2016
Brief Lives: From a rat C90 to a dodgy LC350 via a Z250
From the age of 17 I ran a P reg Honda C90 which I had inherited from my father — he had three in various states of disrepair. I ran it for 18 months. It had an oil leak from the base gasket - I chose to replace this and learnt my first painful lesson about maintenance — put the split link clip in the camchain the right away around. I didn't, on my joyful test run with the engine running well after I’d decoked it, the link gave and the chain punched a neat hole in the engine casings, taking a tooth off the top gear when it jammed on the sprocket. Most of the oil fell out of the engine, but I had a spare split link, put the chain back and got home. We transplanted the engine out of the other running C90 and I was mobile again.
After a while, the clutch packed up - there was a spare gear cluster in the garage so I rebuilt the first engine and patched the hole as best I could with an aluminium plate — it always leaked but not much. C90s are often unfairly maligned — mine went flat out everywhere at 50mph, did 120mpg and gave me a lot of fun. Sure, the chassis rotted but dad had a welder and an old fridge door in the garage... the suspension was packed with washers to tighten it up, so that on a few mad occasions I could take roundabouts flat out - the thing weighed so much that it was very stable so long as you hung your bum over the edge of the seat.
The C90 ended its life bright yellow and totally clapped out from 10,000 miles of thrashing, particularly as I had got into the habit of over revving in second so that the bike didn't start to slow down as I put it into third (top). I went to university and the C90 was loaned to a friend who had blown up his own and never got it back. That seemed like the end for me and bikes — I needed a car to get all my junk back and forth from Norwich to the north of England. Then, in the vacation of my second year, I got chatting to a student in an East Anglian pub who had an A-reg Yam RS100 in his garage which had seized ten minutes after he had restarted it after putting in new mains. I had sorely missed bikes, even though I had only ridden the C90, and couldn't resist. A deal of eighty quid including his helmet was agreed on and I took the bike home on dad's trailer.
Within an hour I had the engine on the bench — I couldn't pull the alternator so I fiddled around with the primary drive gears — suddenly the crank rotated freely in my hands, the nut on the end of the crank hadn't been done up tightly and allowed the primary gear to ﬂoat around and jam up. I put it back together and bingo, one perfect RS100. After the C90 it was bliss, but top gear was uselessly tall, a smaller gearbox sprocket fixed that. The bike would hold 60mph in most conditions and 70mph down a hill. After the bafﬂe had a fight with my hacksaw the bike sounded better and there was a bit more speed. Handling and even the tiny drum brakes felt fine.
The end of the summer came and I rode the bike up to Durham in two shifts, totalling about I eight hours. I kept off the dual carriageways and felt quite at home on A roads where I could go with the flow but had a hard time overtaking. The bike was crap on fuel at 70mpg but I suppose I wasn't exactly gentle with it.
In Durham l passed my Part 2 and found someone who would give me £325 for the bike; I needed something bigger. A Kawasaki Z250 seemed ldeal. One appeared in the local rag for 300 quid. It was a bit tatty but had a new Marshall 2—1 and new shocks. It went okay. had a free top box, so I bought it for £290 with some spares. For a while it was wonderful, big, fast. powerful (after a 100cc) then a catalogue of disasters began. Both discs seized on, the back one glowed red on the way home — new seals. pads, £35 and a lot of farting around bleeding the front and rear systems took care of that. Then a carb diaphragm split — £28 new but I bought a Stromberg diaphragm for 99p at the local motor factor and fitted it with Araldite and a bit of Coke can. This repair lasted for about a month when I repaired it with Superglue and instant gasket, which lasted until I got rid of the bike.
I had also noticed that the bike needed the oil topping up every 100 miles. Out of innocent curiosity I pulled off the breather and white fumes came out, bores or valves on the way out. The camchain was also noisy, so I planned a bit of renovation for the Xmas vacation. Just before the end of term I pulled out the engine and took the head and barrels off — bores looked fine, so I cast suspicion on the valves. I put the engine in the boot of the car and took it home to fix.
A new camchain and valve guide oil seals were fitted. I noticed that the big and small ends were a bit worn, and that the cam bearings were also scored — all on a bike that had done 20,000 miles. All of these bearings were plain, with no shells — I found this very hard to believe, as the only conclusion which can be drawn is that once one or all of them go that's it — party’s over. Back in the frame the motor was a pig to start — smoke billowed out of the exhaust and there was a strange tapping noise...
l ripped it apart again. New gaskets dealt with the oil smoke, and the noise was traced to the pistons hitting the crankcase at BDC, down to the worn conrods. I realised that I had heard it all along, but before it had been largely hidden by the noise from the shagged camchain. I relieved the pistons where they were fouling and put it back together.
The bike was then okay for a while. They are a bit heavy for a 250 but handle well and have good brakes when they are not seized, wet or dry. So why am I so fed up? I set out for home for the Easter vacation on a lovely sunny day. The first 100 miles were bliss at about 75mph on the flat (with a tail wind and not flat out).
Going into Hull the bike overheated — I let it cool and set off again - no problems apparently. 10 miles further on I stopped for petrol, the bike was hard to start and generally felt a bit odd, but there was nothing I could do but carry on.
Then it started pulling on only one cylinder. Half an hour with the toolkit revealed that one set of points had closed. I reset them and then carried on. A bit further on the bike seized and although I got it going again it was obvious that this was the end of the road — smoke poured from the exhaust. the sump was dry and there was no compression on the left-hand side.
It took ten frustrating hours to get the bike home on the trailer — the ditch option looked attractive but I couldn't afford it. Next day the horror story came to an end — a quick strip revealed a melted and holed piston, no oil and therefore no cam, crank, etc. Totally buggered. I sold it to a breaker for 60 quid, I think he felt sorry for me. The breaker didn’t have a kind word for the Z250... don’t bother & get a Superdream!
Eventually. I bought an X-reg Yam LC350 for 700 quid with a brand new Nolan lid and some spares thrown in. It's in loud Marlborough colours but bog standard. It took fork seals and a new rear tyre to get an MOT. Then I changed the gearbox oil. It was EP90, and full of metal fragments — with 10/40W the clutch stopped slipping but 6th gear was obviously in trouble, judging by all the noise. I got a used cluster for £25 but on the strip down it needed a rebore and crank overhaul. £200 later I had a virtually new engine.
I rebuilt it carefully and am now running it in. l'm up to 6500rpm which equates to an effortless 80mph. For the first 300 miles (60mph) I got 55mpg. They are a hell of a lot of fun, my boots are getting worn on the roundabouts, above 5000rpm they pull like crazy and they are thirsty. It's very comfortable and quite capable of frightening me silly.