Stuart Turner

Depends on which model it is. Magneto is always an issue and related problem of oiling plugs, particularly after hard hot running then throttling back. Converting to coil ignition is supposed to help. Ran one for 11 years. 7 of them were good the other 4 were horrible for no clear identifiable reason! Found reciting the catechism while on my knees trying to start it or upside down timing the mag helped. My then labrador hated it - even more than she hated the Seagull.

Then I replaced it (the ST) with a Yanmar 1GM - bliss.
 
I had a Stuart Turner in an old boat. It ran very well but would never start if the plug was hot. I never figured out why, I simply whipped the hot one out, stuck in a cold one and away she went. Keep a few spare plugs and a plug spanner handy.
Always stop the engine by shutting off the fuel, not by shorting out the magneto. If you don't, fuel left in the carb will evaporate leaving an oily gunk that will block the float, choke the jets and result in petrol ending up in your bilges next time you turn the fuel on.
Don't use carbon HT leads and don't use a suppressor cap. Why not the former I don't know, but it makes a difference. As for the latter, it didn't seem to cause any fm or VHF radio interference, but you do get a better spark.
Make sure the bottom of the magneto and the plate it sits on are spotless. It's your low voltage return path. Any tiny bit of volt drop there will cost you hundreds or thousands on the HT side.
Lead free petrol and modern 2-stroke oil is manna from heaven to these engines. No lead to short out your plug and clean burning; beautiful. Measure your oil to petrol ratio accurately; don't guestimate.
You may find the cooling water seacock has THREE positions: Off, Normal (ported to the sea) and Bilge (ported to the bilge). Very handy if you want to clear the bilge of accumulated rainwater (or seawater if she leaks a bit), but don't forget it's in that position!
 
More years ago than I care to contemplate, I had an ancient Stuart Turner in an 18' ship's boat. It wasn't even a marine engine, but off some ex wartime centrifugal clutch driven fuel bunker. So no gearbox, no brakes.
Reading Porthandbuoy's post reminded me that I found exactly the same with the spark plug. If the engine was hot, it wouldn't start unless the plug was replaced with a cold one. This was the very opposite of its predecessor, a JAP Vee Twin, which would only start if the plugs were heated up. This new-fangled diesel stuff is great.:D
 
I had a Stuart Turner many years ago on a 24ft boat; the engine is not the problem, the magneto is. Magnetos are wonderful as they are independent, however, can get very weak and they need to be put on the test-bench to establish their real performance under running conditions.
 
Local boat builder used to fit them. They would buy a pallet load of ten. There was always one that simply would not start in each batch. ST never bothered and would just send another engine.

If you had a good one they were excellent. If not, they were a nightmare.
 
My P55ME had twin coil ignition with two sets of points - one for each cylinder. I had a lot of trouble with it seizing after a rebore but that was the fault of the engineering firm who rebored it too tight. Once that was sorted, it started easily and ran very smoothly, probably due to the massive flywheel.
 
A couple of final thoughts from me. When I took mine apart, the water cooling channels were pretty well eaten away in places especially in the area of the cylinder head gasket.

The silencer and exhaust looked like they were made from bronze and in perfect condition after 30 years. My engine didn't pump the cooling water into the exhaust system but out through a separate skin fitting. Consequently, the exhaust pipe was covered in what looked like asbestos cloth to protect the hull from the heat so watch out for this.
 
I recently gave away most of 2 P5 engines. I had kept one running by cannibalising parts of another.
The guy I gave them two had acquired an almost complete engine but minus some bits like starting cog, chain & handle, carburettor, magneto etc.
He took the lot including some gaskets, spare magnetos and the original handbook.
I also gave him the tips I had learnt from years of Stuart Turner suffering. e.g.
Oil and / or petrol down the plug hole.
Clean / change the plug.
Set the points .
Drain the crankcase.
Swear at it.
He phoned me some weeks later to say that he had reassembled his engine using my parts, but could not get it started.
My reaction was, yes, that sounds like a proper Stuart.
 
In defence of Stuart Turners, they are well made if archaic. I rebuilt one for someone a couple of years ago. Once sorted it was a thing of beauty and it worked too. In a river launch (the OP's question I think) it would be a pride and joy but in the Portland race...no.
 
Interesting you mention draining the crankcase. I had a BSA Santa until recently. It was sometimes reluctant to start and I found that removing the crankcase drain plug and draining out the unburnt fuel would get it going. I think the problems noted with ST engines are common to all older two strokes. Im looking forward to the PBO team restoring the one on Hantu Biri.
DanTribe said:
I recently gave away most of 2 P5 engines. I had kept one running by cannibalising parts of another.
The guy I gave them two had acquired an almost complete engine but minus some bits like starting cog, chain & handle, carburettor, magneto etc.
He took the lot including some gaskets, spare magnetos and the original handbook.
I also gave him the tips I had learnt from years of Stuart Turner suffering. e.g.
Oil and / or petrol down the plug hole.
Clean / change the plug.
Set the points .
Drain the crankcase.
Swear at it.
He phoned me some weeks later to say that he had reassembled his engine using my parts, but could not get it started.
My reaction was, yes, that sounds like a proper Stuart.
Click to expand...
 
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