Weak spark advice please

[Johndoc]

Ok so the bike was running fine last season, left it neglected over the winter. It will not start now. There is a weak spark at the plug, fuel seems fine, carbs all good with fresh fuel. It has new coils, leads NGK caps, points, condensers and plugs. I am stumped! Probably missing something obvious but just cant see it at the moment.  The coils are aftermarket, however it makes not difference when I try an original set. Any advice will be gratefully received.

[hairygit]

New points? Did you clean the greasy gunk from the point faces that is put on as a corrosion inhibitor, if you didn't it will cause problems. Also check for loose connections, particularly the junction by the back brake switch where the points wires join the main loom, often get corroded inside and need cleaning after a lay up.

[Johndoc]

Thanks Hairy, will check the wires, never thought of that. The points are new but bike did run with them, will clean them.

[Seabeowner]

If it's like the 500 the 12V has a long way to go to get to the coils. Ignition switch, fuse, handlebar cut out switch and lots of connectors and long wiring. When the points are open you should get near battery voltage at coil. Common mod on classic bikes is to fit a relay so that the 12V goes strait to the coils. (with only a fuse in line)

[Integra99]

all of the above as said but having had similar issues with another bike... worth looking at Plug gaps? weak battery?

[Johndoc]

This forum is amazing, and Hairy you are a genius! Opened up that connector behind the brake switch and sure enough there was verdigris on the spade of the green wire. Cleaned it up, pushed the button and away she goes.
Thanks again