Could this be the problem

[ChrisTheChippy]

I'm guessing that valve has a tiny bend in it . I'm assuming you have no access to a lathe to check if it's true . Try rolling it on a sheet of glass or a known flat surface it's easier to see any movement as it rotates. If it's bent its basically scrap . That could have happened when the pushrod came loose. Also check inside the valve guide make sure it is scrupulously clean inside . Might pay to run a reamer down it .

[PX207]

I'm guessing that valve has a tiny bend in it . I'm assuming you have no access to a lathe to check if it's true . Try rolling it on a sheet of glass or a known flat surface it's easier to see any movement as it rotates. If it's bent its basically scrap . That could have happened when the pushrod came loose. Also check inside the valve guide make sure it is scrupulously clean inside . Might pay to run a reamer down it .

A mate has a wood lathe

[PX207]

Evening all, I've decided to take the head to Ken de-Groome it's booked in for this Saturday. This gives me some time to get on with some minor issues like touching up rusty paintwork and lucks horn

[PX207]

Update: dropped the head off with Ken who is going to sort the issues and some other work that needs doing. However, it looks like the exhaust valve; which was not seating properly, set off a chain of events which led to the inlet tappet being dislodged from the pushrod. Luckily the Inlet valve is not bent just a little knurled at the collet end, which Ken sorted in 10 seconds

[PX207]

Big shout out to Ken who not only did a blinding job sorting out the cylinder head and other bits! But also spent time explaining some points and giving me answers to many schoolboy questions. Going on 3 day trip on the AJS 20, so will hopefully get around to putting things back together next week

[PX207]

Just thought I'd post an update to close this topic off. So on Friday and with the radio on in the back ground I finally put the bike back together, no interruptions as the rest of the house was at work. Everything went together as planned, apart from misplacing the bolt to secure the front of the exhaust, luckily I had a suitable replacement to hand.

It was nice to see the old girl back in one piece, so I made a brew and admired (delayed the inevitable) for a while. Unfortunately when the time came, I kicked and kicked and kicked but nothing ... time for another brew and a quick phone call. So I had a couple of hours free on Saturday to go over a few things I thought it could be; fuel and spark doubled checked the valves were set at TDC on compression, drained the carb, checked the sump for excess oil. But all was good or so I thought .... turns out that what I thought was a good spark really wasn't, so out with Champion and in with NGK ..... et voila, she's running and it only took one kick.

A big thanks to Ken who has been teaching this youth some new tricks, I remain truly grateful buddy. Next chapter is to get some NGK plugs in the Model 20

Thanks to all the forum members for your wise words and input

[ChrisTheChippy]

Great stuff mate! Enjoy.
You posting here adds to the pool of knowledge somebody else will identify with your mechanical problem somewhere down the line.
Cheers Chris