Valve clearance reduced after lapping valves.

Bike:
1979 Z650 C3 - 38K km (24k Miles).

Everything mentioned below was done while consulting a Kawasaki workshop manual.

Had the head off recently to repair a mangled spark plug thread and while I was there I popped out the valves to replace the valve stem seals and  lapped the valves, each valve was only lapped for 2-3 minutes at most. Before I took off the head I checked the valve clearances and measured #1-5,7 @ 0.08mm, #6 @ 0.05mm, and #8 @0.10mm, and while the head was off I put in new shims going 1 size down for #1-5,7,8 and 2 sizes down for #6 to get them all in the middle of the 0.08mm - 0.15mm and to hopefully account for the valve lapping taking some material off.

Once I put the head and camshafts back on I turned the engine over by hand several times to check the cam timing and make sure everything was all good. Before re-measuring the valve clearances I gave the engine a good few kicks with kick starter to try and evacuate some of the assembly grease sitting between the bucket and shims (in hindsight I put far to much assembly grease on the underside of the bucked). Re-measured the clearances and to my disappointment #1-5,7 were all between 0.05mm - 0.07mm with #6 and #8 0.09mm and 0.10mm. Kicked the engine several times again and turned over by hand a few times for safe measure and same results.

So, my question is did the lapping my valves remove enough material that my clearances tightened enough that I have to go down an additional shim size or was I over zealous with the assembly grease when putting the buckets back giving the illusion of tight valves. Should I just turn the engine over with the starter for a bit to try and flush out the potential thick film of grease or should I just bite the bullet and re-shim the valves?
 

Probably a combination of both, what did you use as assembly lube ?
You may need to run it up to temperature to flush it through then allow to cool fully and re-check

I doubt lube could affect the change mentioned.  Most likely, lapping removed carbon and seat/valve material, tightening the clearance.

Realize also, that positioning the cams, by pointing the lobe away from the valve before measuring, is not the best way to measure clearance.  I say this, because many people do it this way.  If you do, make sure to target the high end of the factory manual spec range, because the measured clearance will be looser than the true running clearance.