I think this might make someone smile - I'm still grinning:
Had this CB250RS running briefly, it died in the Galloway hills. It's since been in the garage 4 years. Finally had a wee look...
Rocker box off shows very worn camchain (wedge shouldn't stick out more than 8mm, or be shiny where it's hitting the engine cover. Ahem). I'd done tappets, then
ignored the loud tapping still present - well, it was a pretty rough bike!



Camchain is VERY DEAR (£50ish!), took off side cover with view to checking tensioner damage, metal flakes, etc, and found this:


Big nut holding on ATU (pulsar, and mech advance) has undone itself, only held on by engine cover! As a result, pulsar senser bit has popped out of engagement with arms/springs of baseplate - no wonder it wouldn't run!
Amazingly, nothing seems damaged! I'll put it back together roughly without changing camchain, just to see if it runs now - if so, it's worth camchain (also a bit of work on carb - butchered by P.O. I hasten to add. I've fixed accelarator, and a couple of other bits, but it leaks a bit).
The only worry is this:
The pulsar senser bit (the oval bit at the front) will fit into the baseplate 2 ways, 180 degrees apart (it could be worse). I think these photos show it assembled correctly - but tell me if you know better!

The baseplate has
TEC stamped at 6 o'clock, and
428 stamped at 12 o'clock. The oval spinny bit has ONE END with a magnet (?) in it (2 vertical strips) - I think it's the end NOT visible in the Haynes book photo, nor the photo above as I've assembled it, where magnet strip is at about 2 o'clock.
Photo below shows magnet strip

Final evidence is in photo below, B stamped in non-magnet end, dirty patch in magnet end...as per Haynes photo.[/quote]
Advice appreciated on whether I've got this right, cheapest camchain choice, and crucially whether I should or shouldn't get a camchain with a split link - I've only done a CX cam (with help) which is totally different (transverse engine split). I'm at. or beyond, my technical ability here!