Decided to check the valves on my 4RT today and haven't done it on this before but have on previous bikes.
All 4 valves were tight, couldn't get the feeler gauges under any of them so set it to TDC (checked Pistons was at top too, valves on the rock although its hard to tell on them) set the crank on the T mark and slackened the adjusters, wound the tappet out and reset to correct clearance then put all back together. 
When I tried to start it, it now has massive compression, it will turn over and can't hear anything untoward but doesn't want to start and the compression just "feels" wrong, so gave up for the day and to have a think. The only thing I could come up with last night at 10pm was that I hadn't reconnected the electric plug on the tank but can't see that making any difference. 

I must be missing something very obvious but any one any suggestions?

hello hoggy you have time timed it up on wrong stroke remove sparkplug and use long screw driver and check piston is tdc with timing mark(T) on fly wheel

Make sure you are at TDC on the compression stroke. And only turn the engine in the normal running direction, don't back up to the TDC mark -- if you overshoot a little, go another 2 revolutions.

Thought I was on the comp stroke as piston was at top (checked through spark plug hole) and valves "rocking" ???

 

Why should I not back it up to get back the the T mark?? 

Valves need to be closed, not rocking, to check valve clearances.

If the valves were rocking they could have been on the top of the lobes= 1 complete revolution out. If so no wonder it won't start as the valves are probably not opening

I did say that

I did say that

 

 

"Doctor, everybody ignores me..."

 

"Next."

Why should I not back it up to get back the the T mark?? 

 

Because of Backlash 

 

You need to be at TDC on the compression stoke i.e. after the inlet valve has closed - not after the exhaust has closed

 

suck squeeze This TDC bang blow not this TDC

Edited May 3, 201610 yr by ourian

Where's the egg on the face emoji??

On the wrong stroke oops, it is 28 yrs since I was taught lol all sorted now though and back running, at least I realised something wasn't right before starting!!