Well I tried but the Atlas is still a work in progress. I’d given myself most of Saturday afternoon and Sunday but just ran out of time – how long can it take to put a 600cc parallel twin together hey?
Initial progress was good with the cases going together with a dab of Loctite 518 but things slowed with the pistons and barrels.
Got the pistons on and the rings but then looking at my piston ring clamp decided it would work better if I put the pistons in the barrels first and then attached them to the con-rods. It took longer than I thought but I think it is the best way with the Atlas as removing a ring clamp would be difficult.
The piston rings are off a Lada (Russian copy of a Fiat) – £35 the pair! The oil scraper ring is made up of three separate pieces so having trawled through a Youtube video or two I sorted out how to fit these correctly (you put the coiled ring in first).
Getting the pistons onto the rods when buried in the barrels was a challenge because of the 180 configuration. You have to get the rods at the point where they are both at the same height and then have a bit of luck to push the gudgeon pin home. With the barrels on I took the opportunity to find the absolute TDC and mark it on the primary case – no hassle to sort the timing in the future hopefully.
Putting the cylinder head on was straightforward. The cylinder head had a new valve seat put in + a light skim. Skimming the head left the fins under the exhaust port very thin – hopefully this won’t matter as it is just decorative with enough meat round the port to hold the exhausts.
So switched of the lights with the engine together and high hopes it would be a straightforward Sunday…
By the time I packed things in on Saturday the cam chain hadn’t been threaded through so I did this before breakfast. I found the best method is to feed the chain down through the cam chain adjuster window and then pull it back up with lockwire attached to the end of the cam chain – if you don’t do this the chain doesn’t naturally loop round the crank.
Mrs A came down to the garage to help hoist the engine into the frame. I though the engine would go in via the primary side but not it has to go in (and come out) via the alternator side. The engine hoist is a must to avoid damage to the frame and with some deft crane work by Mrs A the lump was finally home.
Time slipped away as I put the final drive chain on the sprockets, primary case and then gear lever which enabled me to check the gearbox was functioning. With the gearbox home the next thing to sort is the valve clearances and this proved the killer. All the clearances were tight as you’d expect with refaced valves and seats so it was a case of cams off, grind the shim on the grinding wheel, cams on, cams off etc. I also lost time investigating the cams to get them to spin easily. Some very light emery on the plain bushes seemed to help here but by 18.00 on only two shims done it was time to admit defeat – tired eyes leads to mistakes…
So how damned long is it going to be before I am back on two wheels? I really thought it would be done by the end of the weekend but where did the time go? I guess when you don’t do this for a living you don’t take a time’s money approach and it’s easy to get distracted. I guess also going a bit slowly means you’re less likely to make a mistake.
The big job to do is the valve clearances, make sure the cams are smooth and reattach the cam chain. I think this alone will take two full evenings in the garage and I have a busy week ahead at work…so looks like next weekend which hasn’t raised my spirits but let’s keep looking forward hey.