new top end compresion test

blaster man1

Member
Jul 30, 2014
125
7
38
41
scotland
hi just rebuilt my top end with weiseco piston and new rechambered and milled head do i have to break piston in before i do a comresion test as i done one one strait after biuld and it only red 125psi
 
It should get a bit higher once you break it in and the rings seat. Make sure you do the heat cycles and re-torque head and cylinder after.
 
If you compression gauge has long tube with the Schrader core at the gauge an not at plug insert its going no affect your reading, as the tube adds volume to the combustion chamber
 
dont know ware it was done got it from a freind he got it like that looks like it has about 5mm taken off and alloy removed from dome looks like a good job
 
pic would help?
vitos high compression gasket is 14 thousands of an inch smaller and they say it adds 10psi.
hard to say unless you had cylinder freshened up first,with a new piston rings...leak tested
ken oconnors head is like 30psi more so it you were to start at 120psi...it would be like 150

mine.......

REDESIGNED HEAD 1.jpg
 
pic would help?
vitos high compression gasket is 14 thousands of an inch smaller and they say it adds 10psi.
hard to say unless you had cylinder freshened up first,with a new piston rings...leak tested
ken oconnors head is like 30psi more so it you were to start at 120psi...it would be like 150

mine.......

View attachment 13220
it looks just like ures but ures is shinny
 
Seeing that he is in Scotland, who knows who did it. Other than checking with another gage, won't matter whole lot. Ya got what ya got.
Did you have cyl bored for new piston? Set ring end gap?
 
A KOR re-designed head is set at 22cc for engines running pump gas and will yield 140 - 155 psi with a static compression test. A home porting job will change that number.
i ported using your vids and info raised exhaust 1mm polished exh raised intake 1mm droped 2mm would this lower the comp
 
Fix the leak befor starting it.

The intake area is very prone to leaks, especially if it has been overtightened and warped the cage and boot.

High temp copper RTV on both the block and boot left to dry over night should seal it up.

No more than 5.8 ft lbs on the bolts.