[wristpin]

Fairly certain that pulling the sleeve and sprocket off is the way to go. Atco used a similar system on cutting cylinder drives right through to “modern” Atco 24s. Unless one knows, that hex sleeve just invites the application of the biggest ring spanner in in the box and I’ve seen them actually twisted. I’ve got a few damaged ones that I use for driving cylinders on the grinder.

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[wristpin]

I’m now looking at your image on the PC which is a lot clearer than on the ipad when I did my last post. By the looks of it the ratchet is part of the sprocket – or at least fixed to it. It certainly leads me to believe that the hex component will be either keyed of splined to the roller shaft and will draw off. Unfortunately the only parts books that I can find for that era show a slightly different design of ratchet and as far as I can see the OLC archive does not show your design either.
I suggest getting a couple of pry bars behind the sprocket and try levering it away from the side plate / roller. However if it doesn’t show signs of moving before the sprocket starts to distort, STOP.
Do post an image of the parts that you have removed – presumably the “other half” of the ratchet / dog clutch and what ever holds it on.

[wristpin]

NO don’t attack it with an impact driver, damage it and there’s no going back.
Am I right in thinking that as it is shown in your image the sprocket is free to turn ( not connected to the roller) and that the ratchet is part of, or fixed to the sprocket ?
If that is so, please post an image of the parts that you have already removed from that area. Preferably a better quality image.
I believe that the hexagonal sleeve is splined to the roller shaft and will draw off , possibly with some gentle levering from behind the sprocket. Any levering should be done from as near to the centre as possible to avoid distorting it, but a look at what you have removed will help to establish if that is so.

[wristpin]

At least twenty years old. Quality kit and actually a simple design and easy but heavy to work on.
Plenty of used parts available and standard off the shelf bearings etc. Should you be tempted to fit a more modern engine, stop and consider that the MAG suited the centrifugal clutch in that it would tick over below the bite point but would recover and not bog down when it was time to move off. Many modern engines didn’t like the low rpm needed to disengage the clutch so Ransomes had to fit special build reverse rotation lumps with the drive taken of the half speed cam shaft.
Half choke. Possibly just needs a thorough carburettor clean.

[wristpin]

Chris , memory isn’t what it was , but I seem to recall that you simply undo the nut (left hand thread) and the sprocket pulls away by hand.

If anyone has an illustrated parts list and the end of the cutting cylinder looks to be splined or keyed it is likely that the above is correct.

[wristpin]

As you have surmised, a loose valve seat, not unknown on Briggs engines that have overheated . Providing that the machine has not been run in that state for too long and the seat recess enlarged too much there is a procedure for recovering the situation, which if carried out to the letter should provide a permanent solution. The procedure is covered in the appropriate Briggs manual which is not expensive but does advise the use of one special tool, a valve seat cutter to ensure that the re-positioned seat is concentric with the valve guide. However, if the centring advice is followed exactly you can usually get away without re-cutting the seat.
The appropriate manual for your “L head” (side valve) engine is part number 270962.

EDIT. Should have watched all your video after the discovery of the loose seat! Lets just say, not by the book but sufficient for your purposes!

[wristpin]

Out of interest, what “acid” are you using?

[wristpin]

Early Lasers had Koehler engines, so the starting point is to determine what you have.
If the engine is cranking but not firing the plug the first step is to isolate the engine from the machine’s safety switches etc which could be “saying unsafe to start”.
This is where some engine info is needed as it’s necessary to identify the “ kill wire” that connects the engine’s ignition system from the machine’s key switch ( ignition switch) and the machine’s safety systems.
Once identified and disconnected it can then be determined whether you have an engine fault or a systems fault. NOTE If it’s a safety systems fault, with the kill wire disconnected, the engine will start but turning off the ignition key won’t stop it.
If, with the kill wire disconnected there is still no spark, you have an engine ignition system fault. If the engine is old enough to have a points ignition system, dirty points are the possible culprit. If it has an electronic system, life gets more complicated !

[wristpin]

That bushing with 86-3519. Villiers used 86 and 87-xxxx numbers for quite a few parts, including the crank oil seals on F15s,but on the other hand they may have been their suppliers part numbers. Probably in the 80s I did a complete overhaul on a Monro- Tiller which included having a new axle machined up from scratch and the chap doing the machining for me consulted some tome and found that a Lister bushing ( little end, I think) was just what was needed for replacing those in the MT hull.

[wristpin]

Progress indeed. I like the suggestion of sharing the question of identification with the Stationary Engine brigade.
Off topic, but is that a Champion plug cleaner and pressure tester in the back ground?

[wristpin]

It certainly has an over engineered look , the bottom end would be more at home as the casing of a right angle drive box. If it is a home made engine would the maker have gone to the trouble of manufacturing his own finned flywheel or did Villiers or some other contemporary engine maker unknowingly provide that? Any clues such as casting numbers inside the flywheel?

[wristpin]

Not sure about any Villiers association as I can’t recollect ever seeing an engine from them that has a crankcase split horizontally along the crank line. It was the Japanese who introduced that design to motor cycle engines while British lumps were still vertically split and dripping oil.

[wristpin]

Good suggestion, but I didn’t mean to imply that I have one now but I’d been in conversation with a man from Leicester who has two and neither of us knew the answer to the BUX question. I did have one that I took as a trade in when I had the business but I was doing a bit of post retirement de- cluttering and sold it to a chap from Oxfordshire who apparently has a bit of a collection.
This may be of interest
https://www.outdoorking.com/forum/ubbthreads.php?ubb=showflat&Number=63824

[wristpin]

I think, in- house too. My parents had a new Rotoscythe in 1952 and I was deemed old enough to use it. I well remember that turbine like sound – and also the burn on the wrist from the exhaust, acquired when reaching over the machine to the height adjuster knob rather than walking around the front.

[wristpin]

Definitely check the valves. Check both with the piston 1/4″ down the bore past TDC. The Magnetron electronic ignition coils usually either work or not at all. Genuine BS Magnetron coils are readily available in the UK from Briggs agents but the pattern ones from China are also available from UK sellers at considerably less money and seem to be reliable. Also bear in mind that there is a ready supply of Magnetron coils from engines that have “blown up” from a lack of oil etc.

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