1964 600cc single special

[Dan.Gibbs]

Hi All, first post on the forum, just curious for any thoughts comments on this bike.

Aquired it at the end of the last lockdown as a bit of a project / curiosity. Unfortunately previous owners didn't have a lot of info on the bike, so whoever modified it then it was done 10 maybe 15 years ago. From what I was told it was a 600 single, little used by last 2 owners, the last owner had issues starting it, which I resolved, carb and ignition, the slotted pre-combustion spark plug head doesn't help! Bottom crankcase indicates a G3 and the 1964 frame and case numbers are matching. The paintwork and chrome wasn't good so all that was sorted and now looks good if not original for the purists!

It's always had a small weep of oil from around the pushrod tunnel where the head gasket is located. It's slowly got worse so was time to take the head off and take a look. bore is 87.6 and stroke approx 96mm, so more or less 600cc, I did always wonder if it was a 600 or a 500? inspecting the piston and bore it does seem very little used since built. Piston is marked "Wellworthy 4185-C/1 025326 + 20" Also has a KE stamped on it, maybe the builder? I can't find any info on this old piston, was curious what it was from if anyone has any ideas. The only 600 matchless single I can find is the Typhoon and that from what I can find out had a 96mm stroke (so same as this one) but a bigger bore of 89mm, so maybe this has a Typhoon crank but a different piston?

When I pulled the head off there wasn't any "O" rings in the top of the pushrod tunnels, there was a copper gasket, but no o rings, that explains the leaks then, I don't think the cylinder to head seal was blowing, no tell tale signs of compression gases leaking. But the copper gasket did have oil on it so maybe it was?

I'm hoping the rocker box gasket is standard, will be calling the club spares number tomorrow. Not sure what "o" rings to use, are the club ones ok or anyone have the size and if Viton ones are available?

Some pics below, after taking them I started de-cokeing and most carbon was very light and came off with rag, so again indicates little use since build

Thanks Dan

[dave16mct]

Steve at AMC Classic Spares has the copper gasket and the special O rings you need for it. Best to phone him, very helpfull and knows about the CS. You've a very nice bike. I have the same issue with the 'slot' on my 18CS, what spark plug are you using? I'm using a Champion N5C plus an alloy spacer. A friend with a '63 CS advises not to tickle the carb at all, just ease over compression and kick. It worked the first time I tried it but didn't start first time since. I think I still haven't found the correct setting of advance/retard and choke from cold. Usually goes first kick hot. I couldn't start it at all when I'd finished building it so I made a paddock starter and it started up first time on that. I was flooding the carb with the tickler then.
Dave.

[Dan.Gibbs]

Hi Dave,

Thanks for the heads up re Steve at AMC, will make a call when they open.

I tried a lot of different starting procedures on mine until I found the best way! I'm using a NGK B7ET (BR7ET) plug, it came with the bike, tried a few others but this 4 ground plug...with ally spacer too this seems best, so worth a try.

I've got elec ignition, the points weren't in best condition when I got it and so went with the electronic upgrade and also hoping that gives a better spark, still on 6V though. So I've no advance / retard but with the elec ign it would be fully retarded for starting

The biggest improvement on starting was to modify the carb tickover screw, done this before on other bikes buy adding a big knurled brass addition to the screw so can mod it by hand, I then turn up the tickover by 1/2 a turn before starting, either hot or cold. This gives the engine a chance to "catch" when starting as so often in the past it would fire but not quite catch and trying to catch it on the throttle was hit in miss, but with the mod on the carb I can precisely set the increase tickover and as she warms up turn it down, I have 2 marks on the screw, run and start.

My start procedure is to turn up tickover as above, tickle carb and then kick it over a dozen times with the de-comp lever in, ign off, just seems to help to get a bit of fuel/air in the cylinder. Then tickle carb again, ign on, bring engine up to compression, pull in the de comp lever and bring over compression and kick lever nearly down on the way, release de comp lever and allow kick start lever to come back to comfortable position to give it a good kick. No choke and from cold normally starts first or second kick

Thanks Dan

[dave16mct]

Thanks for that Dan.
I tried The Green Sparkplug Co. for the B7ET and they're out of stock. Not sure about using it with a magneto anyway though as the gap is more suitable for coil or electronic ignition (about 28thou?) I usually go for 20-22thou on singles with mag. But it it helped me start the beast easier I'll try it! Did you make the throttle adjuster or is it available somewhere? Old Norton singles used something like that, the screw had a little tommy bar and you turned it to the start setting, then returned it to the run setting. I'll find a way of doing that, maybe solder a small lever in the screw slot. I did notice it helped if I opened the throttle slightly holding it still by pulling the brake lever at the same time. Got to be carefull though or it'll kick me over the handlebars! My friend with the '63 CS has a compression plate under the barrell so his is easier to kick over.
Dave.

[Dan.Gibbs]

Unfortunately I think the B7ET is no longer made, it's now a BR7ET with resistor, should be ok on my coil ign, but not so good for mag's. I've got a few B7ET's in "stock" I just buy them when they pop up on ebay etc. I think you can still get them from other parts of the world, old stock etc but expensive with shipping and imports.

If you want to try one of the B7ET then more than happy to lend you one to try, if it's better then you know your onto something, if no better then just let me have it back?

You can get extended Amal stop screws, see here https://acmestainless.co.uk/shop/triump ... cba1185463 I don't think that is where I got mine though....memory loss fortunatly I have a lathe so made up a large brass knurled fitting and drilled and tapped the end of the extended screw to hold it on, see pic.

Steve at AMC spares came up good with just the right parts, so thanks for that tip.

Cheers Dan

[dave16mct]

Thanks for link Dan but mine's a monobloc and the screw isn't shouldered, it's threaded all the way down to the head. I'll modify mine, the head is knurled anyway. Thanks for the offer but I'll keep looking and persevere with the N5C for now. Maybe try side gapping one, perhaps it would 'see' the spark through the slot better?
Dave.

[Dan.Gibbs]

Hi Dave, Ahh I did wonder if you had a different carb, sounds like it's possible to mod yours though and do think it will help, I was surprised as to how much I had to turn up the tickover (1/2 turn) to get it to catch and run.

Yep thats what I think with the B7ET, ie the spark isn't hidden by the ground bar but exposed and jumping across the plug rather than up down in the centre, and having 3 ground bars hopefully more chance of the gasses getting to a spark, although from my understanding you only get a spark to one ground at a time and not all 3.