working on a friends bike. had to tear the engine down to remove bolt lodged between crank and case. During reassembly cam across an issue.

the directions i have access to for timing the cams is not clear...
i can rotate the crank to the TDC indicator and then position the cam timing marks level with the head as shown..but im not sure if im in the correct phase..

one more full revolution of the crank and it is aglined with the marks again but the cam marks are now incorrect.

i need to know how to determine at no.1 TDC if im actually in the correct phase..

 

There are a couple if things to keep in mind. The Crankshaft rotates 2 times for each single rotation of the camshafts. If you have the crankshaft in the correct position for setting the cam timing, and you position the camshafts with the marks as indicated, then everything is fine. That initial starting point puts everything in the correct phase. If you rotate the crankshaft 2 times, you'll find that the camshafts are once again back in the proper position. You're good to go.