Oil wells

[Arthur]

Novice scott rider here with my first fit for the road machine just purchased (I have a 1922 model in restoration 20 years so now entirely a newbie)

Just removed crankcase doors on 2 speed super 1930 to find wells full of black oily old fuel, lots of carbon lumps and a BA screw head !!!

Cleaned it all out …one side was fine but the other side had a con rod rather blue (the side with the screw) and also the well that side had a very modest deposit of alloy flakes.

Both cylinders seem to have good compression

My question really is do I fill the wells totally with 40 weight oil before starting, but any general advice would be welcome.

I’m Itching to ride the thing!!

[dave bushell]

The BA screw (depending on size) is probably the small end bush retaining screw. This was discontinued on later models although provision was still there to fit one if you tapped a thread in the small end bush. It’s a good idea to fill the wells with fresh oil after a rebuild or draining and cleaning the wells as this ensures adequate lubrication of the big ends and bores on start up.

[Arthur]

Cheers Dave,

Crikey a BA srew holding the bush in ..never thought of that !

Screw is probably 2BA going on head size but it is sheared under head so thread size cannot be ascertained. Going to try to borrow a boroscope to look up the underside of piston. Keep your fingers crossed !!

Are gudgeon pins secured by brass buffers or circlips???

[dave bushell]

Originally brass pads. Replacement pistons or bushed pistons can have either – depends who supplies them and what your preference is. Personally, I prefer pads, having had a circlip come out of it’s groove and score the barrel. Pad are available in aluminium as well as brass.

[Mike Fennell]

It might be worth considering the advice of Lofty Avis (in 1959) on starting a re-built Scott engine.
It assumes that everything has been assembled in good order, and correctly timed.

1. Drain crankcase contents and re-fit drain plugs
2. Remove transfer ports, pour in 1 – 1/2 eggcups full ( = about 15ml ! ) of starting mixture
and replace covers.
STARTING MIXTURE is 1 part lubricating oil to 2 parts petrol
3. Engine will invariably start, first pot over.
4. Dense smoke may exude, and if too much mixture is used the plugs may oil up.
5. If she smokes profusely give her a quick run down the road to get rid of surplus oil, say 1/4 mile.
6. Keep her at fast idle on the stand and check oil pump. both sides should be delivering oil
WITHOUT BUBBLES in the sight feeds.
7. If bubbles are present open up that adjuster until oil spurts through cleanly.
8. Set adjusters to 1 drop in 4 pulsations ( can later be cut back to 1 in 6 for general riding.)
9. Take her for about a mile and recheck pump for regular feed without bubbles.
10. Try a couple of miles and check again. The pump should be set when the engine and pump are hot.
The delivery when cold will be excessive but this is one of the major faults of the system – just
wind it up from cold to clear the oil.
11. ALWAYS check the pump when going on to a fast road and again after 5 – 10 miles at say 60mph.
They will let you down at the most unfortunate times and in a treacherous manner otherwise.
12. To stop engine for a delayed restart, clamp hand over carb intake, open throttle and stall her
by strangulation. Petrol drawn in will make an easy start.

The rationale behind all this is to ensure there is enough petrol in the crankcases for starting.
Sucking it in from the carb by kicking and/or pushing is exhausting.

[BRIAN MARSHALL]

Hi.
My thoughts are that whatever problem caused all the debris in the wells has NOT been properly investigated and repaired if the crud has been left in there….
I would therefore be apprehensive about firing it up as is.
Is this the ex-Mavro, ex-Glyn Chambers, ex-David Waring bike ?
Brian

[Arthur]

No this is the second one I bought TK 4556, one can only smile and broadly walk onwards.

TK 5209 the ex e-bay, Mavro, Chambers etc one is going to have its doors popped tomorrow for investigation.

Bad timing : My son an R & D engine development guru is off in Sweden cold Ethanol testing with some Italian 12 cylinder monster , but when he returns he is going to bring along a tiny Boroscope which will proove some fun. Pray for me if you would ?

Mention of Lofty Avis plumbs my memory. In the late 60’s I was a member of Southend and District MCC as was Mr Avis and his son (probably about my age) who like me raced in Scrambles. I really do not recollect him on a Scott, but then at the age of 16 I would not have been interested.

It’s a fair cop I’ve been around a bit.

[Mike Fennell]

Lofty Avis was from the Southend area but may possibly not be the man you remember Arthur. For one thing, his eldest son Phillip was only 9 years old when the family emigrated to Canada in 1967. He may have been a member of the Southend Club since he often wrote about a group of motorcycling buddies from the 50’s.

I posted his instructions in response to your query about filling the wells with oil. My personal feeling is that it would probably cause plug oiling and produce a lot of smoke. It must be emphasised that the “starting mixture” ploy was only for an engine being started for the first time after a rebuild.

This re-inforces Brian’s comments of course about the undiagnosed state of the engine which caused the accumulation in the wells in the first place. The blue conrod on that side is another certain sign of over-heating and the bigend rollers will be the same – Lofty used to call this condition “The Hoffman Blues”. Oil starvation is the most likely cause of both the bigend problem and the aluminium flakes from the piston. The oil feed to that side of the engine needs full investigation and Brian is right to advise against trying to start the bike without finding and correcting the faults. Even the main bearings and glands would have to be checked and unfortunately a stripdown is the only proper course of action.

As to prevention in the future, you would find Lofty’s advice on close attention to the Pilgrim pump very valuable.

[Arthur]

Ah some good nerws…after proper investigation with a torch and better light than before the blue on the rod is just black grime, grimier than the other side though. All looks Ok inside the rollers are good, but am, still going to look inside with a Borescope .

[Author]

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