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Number 1 cylinder not firing compression issue

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richardnlambert:
Hi all
I have a issue with number 1 cylinder not firing I have tried a number of thing listed below and now starting to think engine rather than ignition or fuel
The engine sounds good when warmed up but remove plug 1 and still sounds good no change bike tends to overheat after a run.
New coils leads and plugs
Took lead off plug no difference in engine running
Swapped number 1&4 over good spark
New carbs
Cleaned carbs a number of times
Checked valve clearance
Plug is black ( scooty carbon) all rest light brown
Compression check incorrect way throttle not open
1= 70
2-4 = 100
Compression check correct way
1 = 145
2 -4 = 125
Check temperature of manifold
1 = 60
2 -4 = 150 approximately
Used easy start direct into inlet manifold no difference

Any help ideas would be appreciated
Thanks

Trigger:
Is number 1 sparking or just not firing when in ?
Compression is a tad low, should be around the 175 psi mark.
Have you done a leak test on the head to see if any valves are bent ?

richardnlambert:
The spark plug sparks outside The compression test was weird as it was higher than the 3 other cylinders with throttle fully open but lower than the others when closed, not sure how to do a leak test

Trigger:
The temp on the down pipes suggests that there is not enough fuel getting through. Are all the float heights right and were done in the correct way ?

To do a leak test, the head has to be removed . 

richardnlambert:
I adjusted the floats using clear tubes looks like the head has to come off then

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