[fredvincent]

Yes good point.

Always thought it would be good for someone with a lathe and some spare time to make up a batch of the s/s spools for the pump and pop them in the club spares.

I can cope with the rest of the mods but don’t have a lathe sadly.

[fredvincent]

Thankyou Glyn,

At least you have confirmed I have the correct pistons so I can finish rebuilding.

I will just have to build up my right leg.

Regards, Roger

[fredvincent]

I’ll try again and reword it better this time!
Can anyone tell me how to tell between long stroke and short stroke pistons? I understand that there is 1/16in difference in  height from gudgeon pin to crown but unable to find any dimensions anywhere.

Thanks.

[fredvincent]

An interesting update. After running the bike it is still difficult to start. The crankcase now pops instead of plops so the glands are nicely oiled. Thought I better take the thing apart and being a little perturbed at the route the poor mixture has to take, fill the crankcase and port the piston to increase the gas velocity. Took the top end off yesterday only to find in addition to an undetachable detachable head, the pistons are on the wrong way round. That may explain the poor starting and power and all the oil in the exhaust.

As the provenance is now suspect, does anyone have a piston nearby that they could measure the land height? Mine is a long stroke but I have read that the short stroke pistons are a 1/16 in higher. I ask this because the compression feels very high on the kickstarter.

Thanks, Roger

[fredvincent]

I have the omissions but did receive my membership form.
Cheers
Roger Townsend

[fredvincent]

Well thankyou all. Finally today (13th but not a Friday) the bike ran after 44 years. After 5 bumps down a hill and lots of flooding in between, it decided to start on the kick. Started again later on the kickstart and pilgrim pump now feeding oil to presumably seal everything up again. Pity it’s three days late for the Southern Rally. Maybe next year.

[fredvincent]

Currently trying to force oil through the oil delivery pipes from the pump. I am assuming the glands only let oil in somewhere between the transfers closing and the inlet opening but so far haven’t found a point where I can move the oil. However, I remember someone stating that the oil in the pump wells disappear as soon as the bike starts so do the glands let oil in when the crankcase is under vacuum?
My assumption that primary compression was present was wrong. When I put finger over the crankcase drain plug there is no suction whatever when turning the engine over with spark plugs out. Baffling that when turning the engine over with all plugs in there is no leakage sound at all. If the glands were letting by would you not hear something around the flywheel?

[fredvincent]

Yes, I ended up squirting 3 in 1 oil onto the tops of the flywheels through the transfer ports to try and get oil to the gland seals. Then put some petrol in the plug holes but it would not fire. Bike then went back in the garage for more checks on timing and spark. Timing had not slipped and spark still good.
What I do not understand is the cork popping sound bit where you take the plugs out and spin the wheel in gear. I have been doing this and no such sound. Today I tried each cylinder for compression in turn by putting one plug in and turning the rear wheel in gear and found two distinctive compressions per cycle so there must be good primary compression. Could be the thin oil has done the trick and helped the glands seal. My next step was going to be to try and force thin oil down the oil delivery lines from the pilgrim pump with an oil can to feed the glands.
This all seems to be backing up what has been said here in that an engine laid up for some time just needs to run somehow to get the glands working as they should.
So will try the brake cleaner and large hill with new plugs tomorrow thankyou.

[fredvincent]

Thanks for all the tips. Mag was reconned 5 years ago by Brightspark. Nice blue spark with Champion D21 plug gaps at 15 thou. Timing checked and triple checked. Points to correct cylinders checked. I had put oil down the bores and on the skirts through the transfer ports and it is very hard to kick over. Crankcase doors have been checked and transfer ports checked and resealed. Sucking noises from the carb when turned over with no plugs in but no cork popping. In fact there seems to be almost no crankcase primary compression. Bike allegedly was running in the 70’s before being taken off the road so assuming the gland seals are ok mechanically. Could it be they need oil to seal? Not been able to pump oil through the oil feed pipes.
Still seems that mixture is not reaching the combustion chamber.
Have briefly tried squirting wd40 through carb and into plug holes but still will not run.
Will try bump starting tomorrow as a last resort.

[fredvincent]

Just found Richard’s excellent video on timing a Scott which explains how to check which side of the points cam relates to which ht lead. Thankyou Scottparts and apologies for any confusion as I don’t think I could have worded my initial post very well.

[fredvincent]

Well done Andy. Please put me down for one.
I was going to try Brentwins (Black Country) and Llewellyns (Bristol) but I don’t think you will get much cheaper for this small quantity.
You would think that Holders could at least take confirmed orders with a few for stock and sell them at cost to help shift some of the matching gears that are presumably stuck on their shelves.
If you cannot obtain 10 confirmed orders, maybe the Club would be able to make up the difference using Surplus Assets with the knowledge that the gears would eventually be sold.
Regards, Roger Townsend

[fredvincent]

Hi Andy, I would be interested in one.

[fredvincent]

Thankyou both for the replies – I had not realised that Brightspark Magnetos are only a few miles away near Eastleigh, Hants, so I went with them. I was able to see the mag and dynamo tested and stripped down while I waited and am now waiting for the mag armature to come back rewound so it can be reassembled. Pickups were tested – OK cold but broke down when hot (placed in an oven) – so new ones needed. Capacitor was paper and duff as expected and will be replaced with one of Brightspark’s mag points backing plate with built-in ceramic capacitor.

Will report back when the bike is running.

[fredvincent]

Not ideal, but would it be worth looking at the feasibility of having 26T gear rings made and then welded onto a ground down 29T main shaft gear? Or another way?

[fredvincent]

Spoke to Velocette today and they told me ‘nothing planned at the moment – maybe in the future’, adding that the Scott gears were small volume and suggesting that if there was enough demand, they may pursue it.
It seems a shame that all the other gears are available to make up a ‘Medium Close’ set from ‘Modern Wide’, except for the 26T mainshaft first gear.
Not sure how much demand is out there.

[Author]

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