Erratic confusing running

[BSA500]

Hi,
 The A7 specced as a SS is confusing me. It will start ok and seem to run ok. As it gets hotter the bike refuses to tick over and just dies. Sometimes being difficult to start. I have wound in the throttle stop to raise the tickover to help but even then she wants to die. Thinking it might be the mag I pull the plugs and they spark really well nice fat blue sparks. Plug condition sooty so rich. So fiddle with carb settings. You can see where its going a muddle. Also as she gets hotter start to notice a lack of power. So perhaps points gap.
 What I am really asking what should i be looking at. The mag is a Andy from Priory mags put in a couple of years ago. Carb has had a recent clean in an ultrasonic and compressor blow through, new pilot jet,needle and needle jet. Carb spec 1 inch 376,30 pilot, 106 needle jet, 270 main B7ES plugs.
 Plan is check and reset if needed points gap, check regap plugs, check compression because I can, check valve gaps, check/clean slip ring. Check throttle cable is not snagged, wind throttle stop down and open a little. Anything else??
 thanks in advance

[Triton Thrasher]

Points gap and lubrication is routine maintenance.

Got to keep on top of that, as well as the other service items.

[Ted_Flash]

Vent hole in petrol cap clear?

[BSA500]

Yes a service is on the list and the vent is clear.. I am basically resetting and checking all the normal stuff and see what happens. I have fiddled around too much I think

[KiwiGF]

Hi,
 The A7 specced as a SS is confusing me. It will start ok and seem to run ok. As it gets hotter the bike refuses to tick over and just dies. Sometimes being difficult to start. I have wound in the throttle stop to raise the tickover to help but even then she wants to die. Thinking it might be the mag I pull the plugs and they spark really well nice fat blue sparks. Plug condition sooty so rich. So fiddle with carb settings. You can see where its going a muddle. Also as she gets hotter start to notice a lack of power. So perhaps points gap.
 What I am really asking what should i be looking at. The mag is a Andy from Priory mags put in a couple of years ago. Carb has had a recent clean in an ultrasonic and compressor blow through, new pilot jet,needle and needle jet. Carb spec 1 inch 376,30 pilot, 106 needle jet, 270 main B7ES plugs.
 Plan is check and reset if needed points gap, check regap plugs, check compression because I can, check valve gaps, check/clean slip ring. Check throttle cable is not snagged, wind throttle stop down and open a little. Anything else??
 thanks in advance

How worn is the carb? A worn slide often causes an erratic idle, albeit the idle speed usually goes up when hot, as air leaks past it.

[Peter in Aus]

NGK plugs could be your problem, If not made in Japan.

[BSA500]

Found it. Checked mag,plugs,carb all good compression 110 psi both cylinders . Last check valve clearances , timing side inlet drive side exhaust no gap, timing side exhaust drive side inlet about 3 thou. That'll do it the hotter the engine the worse it ran

[groily]

Would also account for the power loss, logically. Well sussed!

[BSA500]

Nice to have a clear reason for once. Thought the valve clatter was quiet 

[Rex]

Occam's Razor again..

[Triton Thrasher]

Now you know why there’s a maintenance schedule.

[groily]

If the compression was reasonably good, probably no damage to valve seats from tight / negative clearances 

[BSA500]

She seemed OK after resetting no issues

[Klaus]

Remember, a noisy tappet is a happy tappet

cheers Klaus

[RichardL]

They’re not called “tappets” for nothing.

Richard L.