Cold compression readings

[facepants]

What should normal compression be on a cold motor?

Thanks

[werase643]

ya don't take readings on a cold engine......

ya need the metal to temp so you get a good seal and proper tolerances.....

warm it up for 5-10 min and then pull the plugs
no big deal

[sledge]

I will back Ken up on that, compression readings should be taken with the engine warm and the valves set correctly. 

Section 3-1 of the manual states overhaul the engine when......

Compression pressure in one of the cylinders is less than 800kPa (8kg/cm2, 114psi)

Difference in compression pressure between the two cylinders is more than 200 kPa (2kg/cm2, 28psi)

Both compression pressures are below 1000kPa (10kg/cm2, 142psi) even if they each measure more than 800kPa (8kg/cm2, 114psi)


So the answer is........if 1 cylinder is below 114psi, or if the difference between cylinders is more than 28psi, or if they are both below 142psi the engine need attention.

[DerekNC]

Also be sure to open the throttle when checking. I had a 50psi difference between a closed throttle and open throttle.

[werase643]

hot 165-180 range
but cold, i've seen 100-140....and that will scare you to think your engine is fried