More problems starting.

[duTch]

 

........If only the mags had slotted holes it'd take a lot of the hassle out of it...

 It can, and has been done 

[Greybeard]

That's another mod for the list

[coater87]

That's another mod for the list

 

 This single change could potentially save hours and hours of frustration over the course of a bike owners life.

 Lee

[BSA_54A10]

Well I have been using piston stops for a long while when I set timing.
Find the right advance then screw a bolt down the plug hole till it touches the piston.

[lawnmowerman]

Well I have been using piston stops for a long while when I set timing.
Find the right advance then screw a bolt down the plug hole till it touches the piston.

...........but don't forget to take it out again - a problem for us with advancing years 

Jim

[Joolstacho]

I seem to remember some years ago, alloy mag pinions with elongated mounting slots for fine adjustments.
Had a separate centre section with the taper mount, and an outer gear section that bolted to that. (Perhaps I dreamt it, or maybe it was for Velos).

[BSA_54A10]

Well I have been using piston stops for a long while when I set timing.
Find the right advance then screw a bolt down the plug hole till it touches the piston.

...........but don't forget to take it out again - a problem for us with advancing years 

Jim

Funny you should mention that 

[muskrat]

G'day fellas.
The slotted mag mounts duTch mentioned  is in this thread. https://www.a7a10.net/forum/index.php?topic=13132.msg105254#msg105254  Well done Richard "orabanda".
Cheers

[AdrianJ]

Starting to get somewhere. Compression tester arrived.
LH cylinder 100psi, RH cylinder 20psi.
Got to find time now to get the head off and see what's happening.
I lost the nipple off the throttle cable a while ago, thought it came out the bell.
I'll find out early next week.
Adrian.

[lawnmowerman]

Now we are getting somewhere!
Before you remove the head it may be worth squirting a little thick oil down the faulty plug hole then try it again. If it improves then you know you may be looking at faulty rings / bore. If it does not improve then it points towards valves (bent?), head gasket and rocker clearances.
Valve timing should be ok if you are getting good compression on one cylinder.

Jim

[AdrianJ]

Thanks Jim,
I'll try that, but I bet it's a stuck valve.
Adrian.

[muskrat]

G'day Adrian.
I agree, a bent/non seating valve. You'll probably find the tappet clearance has grown on the faulty one.
Cheers.

ps: When checking compression the throttle must be held wide open and a good few compression cycles {(I do 10) then need a beer}.

[Duncan R]

Starting to get somewhere. Compression tester arrived.
LH cylinder 100psi, RH cylinder 20psi.
Got to find time now to get the head off and see what's happening.
I lost the nipple off the throttle cable a while ago, thought it came out the bell.
I'll find out early next week.
Adrian.

Careful with that tester, is a cheapo one of EBAY? I used one and it gave random readings leading me to believe that one cylinder was way down on compression and there was nothing wrong. This is quite common with these cheap testers

[AdrianJ]

Yes it is a cheap tester, but the readings are consistent.
Adrian

[muskrat]

G'day Adrian.
Is it a screw in or just a hold over the hole type?
Cheers