TOPIC:

Incorrect cam timing will make the pistons hit the valves bending them, this will make them stay open, they may not look really bent, and they seem to move ok, but they don't seat properly, but believe me it can happen, I had a failure of the tensioner and a cam chain jumped a few teeth, bike was only idling at the time, it didn't sound nice, anywho after replacing the valves, chain and the tensioner all is well. The holder for the shim that covers the valve spring is a "bucket" , well that's what I call it, hope it's not valves bent, but worst case it could be.

Hi Ian what size shim's are you down to Eg 270/260/250/240 mm if your clearence didnt change i,d be just trying one cylinders clearence and see how smaller shim i have to put in till i got the right clearence then see if your compression is any good .
Cheers chuck

The intake shims I used to drop it down were 2.50 and 2.45. I dropped it down 0.10 on each valve assuming originally that someone had done an adjustment incorrectly and that 0.10 would at least give me some form of measurable clearance.

Hi Ian you would have thought .10 would have given you some sort of clearance but who knowns if the intake valves are tight enough to not let the bike start they would have to be very tight i would pick an easy cylinder and do a compression test if low or no compression reduce the intake shim on that cylinder only till i get correct clearance and compression you can get shims as low as 2mm .
Hope this gives you some ideas
Steve

It sounds very much like bent valves to me.
If the pistons have touched the valves, they will not sit perfectly in the valve seats, meaning the top of the valve will be in a lower position & create the problem you have with gaps.
The double spring valve spring set up on the 1300 has a great deal of strength in it so its unlikely the valves are stuck in the guides, unless it has been left in damp or wet conditions for a long time.
Its a cylinder head off job no matter what, which is no big deal really if you are ok with that kind of work.
Best of luck & please let us know what you find.
Pete

Ian any luck with your valves staying open problem
Steve