Like many during lockdown, Simon Bowes suddenly found himself with a lot of time on his hands. But he’s managed to keep himself busy with repair and restoration projects including motorbikes, a generator, a welder and even a washing machine.

MARCH 23, 2020: that’s a date for the diary. Probably a date for the memoirs I’ll write once I’m too old to use a chainsaw. Looking at how I’ve been getting on in isolation, that might be sooner rather than later.

I’d better explain. I parked my forwarder up on 23 March after meeting with Garth Dearden, my FWM, who is the area manager for Euroforest. I was a bit wary when he took over from Steve Dresser, who I’d worked with for almost two decades and counted as a personal friend. It was a great loss when he passed away from cancer. His stoicism in the last few months of his life was inspiring. He was a brave man and is sorely missed. Anyway, Garth is a more than competent manager who is good humoured and willing to listen (an attribute sadly lacking in many managers).

I met Garth to decide what was going to happen with lockdown on the cards. It was decided our job could carry on, as we were cutting biomass for local fuel producers. I would not be contributing myself, other than to keep the machines supplied with fuel, oil and spare parts. I was going to join my wife at home for a 12-week isolation period as she was one of the 1.8 million UK citizens categorized as ‘shielding’. I got home that day in time to watch the news briefing where Boris announced the lockdown. Impeccable timing.

The first two weeks I was occupied with the FCA’s response to members’ concerns over coronavirus and getting my own business in order. I had a stack of jobs that needed doing. I talked to one estate forester who, with time on his hands, had cleaned his oven. I wasn’t going to go that far, but I did pull our washing machine apart to find out why it periodically showed a fault code and found half a chip fork jammed in the drain pump. Once all the domestic stuff was out of the way, I turned to the more enjoyable tasks.

Five years ago, I rebuilt the engine of my 1976 Kawasaki Z1000. I stripped the frame and repainted it at the same time. The engine and frame were sitting on my bike bench where they’d been ever since I’d put them back together. So, in a spell of fine weather, it rolled out of the shed and fired up on the button.

Forestry Journal: The Kawasaki KL250, every 17-year-old’s dream back in 1978.The Kawasaki KL250, every 17-year-old’s dream back in 1978.

In an act of supreme self-control I warmed it up and, having satisfied myself it was fit to ride, wheeled it back into the shed to await the day I could ride it on the road. I did realise its flat bars were no good to me with my dodgy knee. I had fitted higher bars on the last road bike I had – a Suzuki SV 1000 I sold last summer – and I went onto a well-known internet auction site to look for the same ones for the Z1000. I found them made by Renthal, a UK company that has made handlebars and bike accessories for decades.

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I bought a Kawasaki KL 250 trail bike last summer. It’s an American import, a couple of years newer than the Z1000. I spent an enjoyable few hours working on it, improving on the work I’d started the previous autumn. I soon had it going, although I had to strip and service the clutch that was stuck solid. I spent another couple of hours breaking it down to its component parts and filled a further couple of days painting the frame and all the small brackets and fittings. A change in the weather and the unfortunate fact I was having to scrape consumables up from my meagre stocks meant I made a major mistake.

It’s amazing how long you can make a sheet of 80 grit last when you can’t nip into town for another pack. However, trying to use the same thinner/hardener for all the part tins of paint you have doesn’t work and the 2K hardener that worked perfectly in the gloss black I used on the frame wasn’t so good on the non-reflective black I used on the fixtures and fittings. It took a week to go off completely, which held the rebuild up.

Forestry Journal: Always the easiest part of a restoration.Always the easiest part of a restoration.

With the bike build on hold, I turned to a less-than-appealing project I bought many years ago: a 4.2 kW generator. It has a 13 hp Honda twin-cylinder engine fuelled by LPG. There was a time when we had regular power cuts in the winter and would plug it into the house electrics so we could at least run the lights and boil a kettle. In recent years it was relegated to occasional trips out in the van to run angle grinders, compressors and similar undemanding power tools. It doesn’t have the grunt to power a welder and is a brute to move, so it was replaced by an upright 2,500-watt generator that can be manhandled by one person. The trouble with the Honda engine was the last time I tried it, it wouldn’t start. Setting to work, it was quickly apparent that all the switches and solenoids on the gas supply side worked and the engine would turn over if I bashed the starter with a hammer while holding the key in the start position. That’s old-school diagnostics. Unfortunately, the Honda isn’t an old-school engine.

It took two hours to get the starter off. The carrying frame, radiator, flywheel and most of the wiring had to be removed. The radiator fan needed an M14 bolt to get it off, which is an uncommon size. Fortunately, Kawasaki axle bolts from the ‘70s and ‘80s are M14. The flywheel needs a special puller that no one has, so I made one by drilling three holes in a piece of 10 mm plate steel, using the fan shroud bolt holes to pull against.

Forestry Journal: Two keyways in the flywheel and a very unusual thread size for the correct flywheel extraction tool.Two keyways in the flywheel and a very unusual thread size for the correct flywheel extraction tool.

The starter had a stuck brush and one of the field magnets had fallen off, probably as a result of me bashing on the motor casing. I glued the field magnet back on and filed the copper brush back to shape so it slid freely in and out of its holder. I fitted the starter three times before I got it to work properly. A small insulator had dropped out without me noticing and, though the motor would spin freely, it didn’t throw the starter gear out until I sorted the insulator by fitting some small O-rings onto a bolt where it fitted through the case.

Finally I got it running. I suppose when this is all over I should either fix it in the back of the van or sell it to someone who needs one.

With that ticked off the list, I moved on to the real test of skill and endurance – the JLo welder. This is a Rockwell engine with a Hayter welder gen coupled on a wheeled frame and almost everything about it is awkward and ugly apart from one thing: it’s a brilliant site welder, if you can get the engine started.

I’m an even six foot and far from a weakling, but I haven’t been able to start the bloody thing for a few years. It does have a spark if you can turn it over fast enough, but it isn’t easy with a pull starter. This is back to ‘old school’ again. To start it, you take about six foot of thin rope and wrap it round a pulley bolted to the flywheel. Once you’re ready you have to pull the entire length of rope off that pulley as fast as you can to spin the engine as fast as possible.

Forestry Journal: The piston in this German Rockwell engine is ‘kaput’.The piston in this German Rockwell engine is ‘kaput’.

I’ve always been under the impression this engine has loads of compression because it’s a pig to pull over, but I had an epiphany when I was beginning to feel light headed after trying to get a spark for about 20 minutes: “Why is it so hard to pull over with the plug out? It shouldn’t have any compression and the heavy flywheel effect from the generator should keep it spinning, which it isn’t.”

I unbolted the generator and split it from the engine. Suddenly, it was easy to spin the engine over. A bell rang in my head as I realised it had no compression.

Forestry Journal: The cylinder isn’t much better than the piston; the ends of the piston ring should almost meet.The cylinder isn’t much better than the piston; the ends of the piston ring should almost meet.

The Rockwell L372 engine is a 372cc piston port two-stroke single-cylinder air-cooled stationary engine widely used in the late ’60s and early ’70s before emission regulations killed off utility two-stroke engines in the USA. The Rockwell was mainly fitted in snowmobiles, but it became popular in water pumps, generators and portable welding units like the JLo.

I tried spinning the input shaft to the welder unit and turning it by hand wasn’t easy. There was more drag than I’d expected and I could hear a distinct dry bearing sound. Sure enough, the outer shaft bearing was as dusty as a Yorkshireman’s wallet and, after spraying some liquid grease into it, we had a much happier experience, but a new bearing was required.

Forestry Journal: Getting to the starter motor requires a major strip-down just to get one crucial bolt out. A new starter motor costs almost £300, so repairing the old one was essential.Getting to the starter motor requires a major strip-down just to get one crucial bolt out. A new starter motor costs almost £300, so repairing the old one was essential.

One good thing about two-stroke motorbikes is I grew up taking them apart (they were sacrificed around the farm in large numbers). The cylinder head and barrel took about 10 minutes to get off and one look at the piston told a story: this Rockwell engine had seized on numerous occasions in the past, it had no cylinder-head gasket and the bore hadn’t been true for a long time. In order to get an idea of how true the cylinder bore is, you remove a piston ring and fit it into the bore near the top. Using a feeler gauge you measure the end gap in the ring. I’d guess a 372 cc engine with a bore of almost 80 mm should have a piston ring end gap of about half a millimetre. This engine had a 3 mm end gap which increased to almost 4 mm halfway down the cylinder. There’s little wonder it wouldn’t start. Regardless of whether it has a spark, the top end of this particular engine was junk.

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A piston-port two stroke depends on a good seal between the piston and the cylinder for several reasons. It needs compression to squeeze the fuel air mixture in the cylinder to create a big bang when the spark ignites it, and it needs a seal to create crankcase pressure to force the new charge of fuel in the bottom of the engine up through the transfer ports to fill the cylinder for the next compression stroke. It also needs to create negative pressure to pull the next fuel air charge into the bottom end from the carburettor.

Forestry Journal: JLo welder bought for spares is in far better condition than the original so it’ll get a refresh once I find a flywheel puller.JLo welder bought for spares is in far better condition than the original so it’ll get a refresh once I find a flywheel puller.

It was time to go back to that auction site I’m so fond of, type ‘Rockwell 372L’ into the search box and hope. There were dozens of entries for gasket sets, pistons and cylinder heads, most in the US. I scrolled further down and there was a complete JLo almost identical to mine. ‘JLo welder, engine complete but welder unit not working’, it said. Where was it? Just outside Scarborough, less than 20 miles from home. So I bought it.

My new purchase was left languishing for a couple of weeks until it was worth going out to run several errands at once. Lockdown done properly at that time required a military-style decontamination when I came home, so I didn’t want to go out often.

The bought-for-spares JLo was covered in dust and grime from sitting in a shed. I got it on the bench and gave it a clean before inspecting it. The exhaust was trashed – it had been dropped at some time and the whole lump had landed on the exhaust – but otherwise it seemed well looked-after. The fuel tank was missing its cap and was full of flaky rust. The fuel tap was complete and it worked smoothly, the carburettor was all gummed up but wasn’t worn and the governor was smooth in operation. It also felt like it might have the correct damping oil in it. I pulled the spark plug out and to my surprise it was a standard short-reach NGK plug often fitted in chainsaws, a BPMRA6.

This wasn’t a high-performance engine, but I already knew that. The big question was: would it have a spark? I mixed some two-stroke fuel up at double strength and sloshed a good measure into the cylinder before winding the rope on and giving it a healthy yank. Nothing.

After a dozen attempts I realised I was heading for a coronary so I stopped and accepted the inevitable. The flywheel would have to come off. Removing a Rockwell flywheel is about as welcome as being told you need a digital rectal examination. It might just need the points cleaning, but more likely it’ll need a condenser.

I stripped the carburettor and the bent exhaust and took a good look at the piston and bore. It all looked good and the piston had three rings, not two like the other engine.

To get to the points, you have to remove the starter rope pulley to reveal three access slots in the flywheel. What you really need to see is a dirty set of points, a bit of gooey crud or a bit of light corrosion but no, these points were spotless. The condenser, then.

The flywheel is removed from the end of the crankshaft which it is keyed into with a Woodruff key. Oh the joys of being an apprentice faced with his first Woodruff key all those years ago, using a special tool called a flywheel puller!

Forestry Journal: A terrier, a 1976 Z1000 and a Transit van. What more can a man want?A terrier, a 1976 Z1000 and a Transit van. What more can a man want?

There are numerous types of flywheel pullers, but this machine required a bolt-and-screw type. This consists of a large bolt that screws onto a thread in the flywheel. Down the centre is a screw with a fine thread that pushes against the end of the crankshaft. The theory is you fit the puller into the flywheel centre then wind the screw in until it pushes the flywheel off the crankshaft taper. In reality, you tighten the screw down as hard as you can then hit the end with a hammer in an attempt to shock the flywheel loose. What happens next varies. Sometimes a little heat works, but generally increasingly extreme measures are used until there comes a point where something is about to be damaged irreparably or the project is abandoned.

Why not just buy a puller? Well, not just any will do. There are two types; male and female. Small ones are generally male, larger ones female. This one’s male. There are also metric and imperial. As this is an old engine you’d expect imperial. And there are pullers in right- and left-hand thread.

So what do we think? Have a guess. We know it’s male, so it should be reasonably small, say under 30 mm or 1-1/8th, and it should be imperial and hopefully right-hand thread.

My thread gauge says it’s metric, 1.5 mm. Bit of a surprise until you look at where Rockwell engines are built – not in the USA, but Germany. And it is right-hand thread. The easiest way to find out a thread size is to eyeball it and pick a bolt you think will fit. Any mechanic or forestry contractor who maintains machinery will be able to spot M8, M10 and M12 by eye and nine times out of 10 it’s an easy job, but what about when it’s a blind hole with a crankshaft end sticking up the middle? You can’t thread a bolt into that.

It’s time for a vernier, or a ‘very near’ caliper, as Tungsten Tommy Butler (one of the mechanics I worked with) used to say. The question was always, “Why do you call it a ‘very near’ caliper?” The answer: “Because you’re using it boy. If I’m using it, it’s an exact caliper.”

Measuring the hole and referring to a thread chart, the Rockwell flywheel measurement equates to M40, which is a bugger because you can’t buy male M40x1.5 mm flywheel pullers. You can buy female ones, but I’d need to get an M40x1.5 mm bolt, cut 20 mm off the end and drill the centre out, then use it like a sleeve into both the puller and the flywheel.

The only suitable bolts I can find aren’t bolts, they’re cap screws – Allen bolts with socket heads which are always at least 10.9’s, much harder to cut and drill. Shortest length available is 80 mm and price is around £50 each. I only paid £100 for the welder!

This isn’t looking good, is it?

Time to reassess and come back with another plan.

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