Decent cylinder compression but cold exhaust?

[The Jimbonaut]

Just finished a valve clearance check, replaced a few shims and now have 0.005" clearances across the board. Emptied a can of Honda's carb/combustion chamber cleaner into the carb intakes and compression check now looks better -

#1 - 140 (130 before)
#2 - 150 (same)
#3 - 165 (150 before)
#4 - 165 (150 before)

Question - although the compression has improved, cylinder #4 now has a cold exhaust, whilst the others are hot after running the bike for a while. Ok, not cold, but only mildly warm. Plugs on #3 and 4 look a little oiled.

Weird?

 

[amc49]

As soon as plug wets from fuel or oil it begins shorting down side of electrode (fouling) to not fire. New plug time if the residue gets cooked on any at all to reinforce that condition. Only like glassbeading will bring the plug back and that brings its' share of issues too. The carb/cleaner thing you did can easily foul plugs, that has to clear out. Or your 'oiled' thing. Valve seals die pretty bad on these too.

If OEM ignition, they are weak and just enough to fire the plugs with everything just right, they wet out easy.