Lister A Junior “won’t take much to get it running”

“won’t take much to get running”
This was last year and I bought the engine. I should have asked the chap why he didn’t try then

So, I’ve started a new thread as there’s more problems than just the engine feeling “tight”. As I’ve started to investigate why it wouldn’t even try to fire, this is what I’ve discovered:

1 compression low
2 flywheels don’t turn freely, seem to be binding slightly. As Appletop has said, may need to investigate shims or lube on main bearings
3 carb has been off and reassembled incorrectly
4 piston rings look brand new but the edges are really sharp, perhaps this is what’s caused the damage
5 valve seats are really clean, exhaust valve has clearly been ground but not quite all the pitting has been removed, possibly not sealing properly

My main area of concern is the bore, it’s very badly scored and I need your expert thoughts please as to what my options are



Is the bore repairable? Below is the piston for reference



Thanks in advance peoples, appreciate any advice you may have
John

Measure the bore and if not at top limit it may be possible to hone out the scores.

Alan

Hi John, I have noted the two parallel gouges shown running up the cylinder at 6 o'clock in your picture. They look very reminiscent of the scoring I had in a Velocette Viceroy engine which was caused by the gudgeon pin contacting the bore, due to the circlip being missing or broken. Hopefully the damage is not as severe as it was in my engine which required new cylinder liners to be fitted and you will be able to hone out sufficiently, as suggested by Alan. Best of luck.

Neil






Viceroy engine cylinder with similar score marks, caused by a loose gudgeon pin.

neil (LE) wrote:Hi John, I have noted the two parallel gouges shown running up the cylinder at 6 o'clock in your picture. They look very reminiscent of the scoring I had in a Velocette Viceroy engine which was caused by the gudgeon pin contacting the bore, due to the circlip being missing or broken. Hopefully the damage is not as severe as it was in my engine which required new cylinder liners to be fitted and you will be able to hone out sufficiently, as suggested by Alan. Best of luck.

Neil

Viceroy engine cylinder with similar score marks, caused by a loose gudgeon pin.

Ouch!

Well, that was my first thought when I took the piston out, especially when the gudgeon pin easily slid out with no clips etc. However, in the piston there’s no recess for a circlip and looking at the bore, the scoring is all round the bore, not just where the gudgeon pin could contact.
Now, here’s my quandary: In the Lister A manual, the piston assembly shown on the exploded diagram is slightly different to what I’ve actually got, the manual shows a clip on the pin. However, there’s another Lister manual specifically for the Junior which shows no pin but a brass cap on one end, that’s the type I have in this engine. So if there’s no clip, what stops the pin from sliding onto the bore?

Also, the piston itself, there’s the 3 rings, but the recess for the oil scraper is practically nonexistent, the Junior manual only shows 3 rings. Presumably then I don’t need an oil scraper?

Anyone know what the actual differences were between the standard A and the A Junior? Can’t really seem to find anything documented

Regards
John

The plot thickens! Had a spare hour today so removed mag, tank and drained the oil. Look what I found in the crankcase! Is this a bearing shim?




Regards
John

I'm not familiar with this engine; can't even guess what that is, that you found in the crankcase.

But, it is the brass cap on the gudgeon pin that stops the pin from from contacting the cylinder wall. I would expect there to be a brass cap at both ends of the pin, and also expect the outer face of the caps to be slightly convex. The brass will not damage the cylinder.

Looks like half of a crankshaft oiler ring.