Intake valve oddity

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A pressure test on the cylinders is a good way to diagnose problems. With plugs out, lock engine at tdc on compression and blow air into cylinder from a compressor. Ie bike in top gear with foot brake applied. Listen then to the exhaust, the inlet and with a valve cover off, listen to the crank case. If you hear air rushing, then you have found the problem. You may not hear a blocked exhaust this way but removing the muffler will eliminate that. Blocked muffler is probably rare but it can happen. Likewise , with the valve covers off, you can turn the engine over and look for a valve lift problem [ as Jim has mentioned ] .
Dereck
 
Many apologies for the great delay in this update. Thanks again for all the constructive input as well.
Life got in the way for way to long. Retirement,Grandchildren,etc. An almost life altering health issue, 3 doctors + 1 chiropractor wrong!! I'm fine as hell.
Also lost all the local machinists to who I would trust doing a valve & guide job. Ended up buying the tooling & doing it myself.
Valve guides were worn, valves & seats due for attention, but nothing unexpected. Double checked cam lift & it was perfect to specs. Bores were beautiful.
So that left the loose upper end of the offending pushrod. Out of the bike it just falls off onto the bench when turned upside down. Found another a bit loose, so I
replaced all the pushrods. Also replaced the springs and valves along with new guides. Spent a lot of time fitting the new valves so that they were perfect in contact
with the seats in all respects.
Reassembly went smooth. A few kicks with loads of compression & nothing!!! Traced the wiring for the Boyer & coils, & yes I did miss one wire laying right where it should be but on top of spade connector not on, though it was visually where it belonged. Plugged it in, and first kick she started & ran like a sweetheart.
Tweeked the carbs a smidge during a brief warm-up & then checked all over. A-Okay, and then a 10 min ride. Check all's well. 40 minute ride followed.
Retorqued head, and rechecked/reset valve clearances. Beauty.
Today went for a beautiful 1 hour tour.
Happy Ending. The only smoking gun seemed to be the loose pushrod top. I still find it hard to believe, but what the hey.
Looking to a great year of riding, & hope you all have the same.
Cheers
 
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