Firstly only one special tool is required & this can easily be made by your local machine shop. The tool required is pictured in the Clymer manual & is used to immobilise the cam chain tensioner when you remove the cam shafts.
The tool is based on an M20 x 1.5 bolt 43 mm long. Get this made on a lathe from hex tool stock as standard bolts will be high tensile steel, & too hard to drill. The locking sleeve is 25 mm long, make sure the OD is also only 25 mm or it will exceed the dimensions of the machining in the timing cover. Drill a hole as close as practical to the edge lengthways through the bolt. Make this hole 4.6 mm, you can then use an extra long 4 mm Allen key as the pin. This tool cost me $40.
Measure your valve clearances & if you need to change a bucket proceed as follows.
Return the engine to TDC on compression stroke No 1 cylinder. Both triangle cut outs in each camshaft sprocket will be at 12 o`clock pointing down. Check also that the slots at the rear of each camshaft are parallel & horizontal [note Clymer says vertical, perhaps relative to the motor, I am using the ground as reference].
Unscrew the blanking plug from the middle of the timing chain cover. Screw in your special tool 3-4 turns until the 4.6 mm hole is uppermost. Looking down past the camshaft sprockets insert the 4 mm Allen key until the end is just past the chain. Then rotate the tool clockwise until you have firm pressure on the chain & lock with the locking sleeve. NOT too much pressure as you cannot compress the tensioner [contrary to what it says in Clymer] as it has a non return ratchet in it, you are merely holding it in its present position.
With lacing wire & using the most convenient hole in the camshaft sprocket, tie the chain to each sprocket to prevent incorrect reassembly. It is possible to remove only one camshaft if required. Hold the required camshaft with a spanner on the cast in hex & remove the camshaft sprocket bolt. There is enough room to slip the sprocket with chain still attached with lacing wire forward off the camshaft. Then follow Clymer to remove the camshaft retaining caps & timing chain guide. You can remove the guide [brown nylon between upper & lower camshafts] with careful wiggling even if you are only removing one camshaft & still leave your lacing wires undisturbed.
When reassembling make sure the camshaft is in its correct position before tightening the caps. The rear slots will be horizontal, & the front locating spigot for the camshaft sprocket will be inboard. Prevent the shaft from turning as you tighten the caps with a spanner on the camshaft hex. Because you have wired each sprocket to the cam chain it is impossible to mistime the motor.
Please note this is from Mark Holland via my wife's e-mail.