Question about Milling Heads

Adam McGillivray

Adam McGillivray

New Member
#1
#1
I ordered a bare 14cc head for my gx200 from affordable go karts and i got stock size SS valves, 18lbs and 26lbs springs heavy duty aluminum retainers and keepers and to go in it but im having it milled down .065 and fully ported by ajax racing engines. Now my question is am i gunna run into problems milling that much someone told me i have to unshroud the valves i dont know what that is and what springs should i use. The gx200 was a blue printed motor built by dominator race engines. Iv done more work to its since i got it. It now has a straight header with rlv muffler, ngk race plug, 3 degree advanced timing, mikuni fuel pump, velocity stack with knN oil type filter stock carb with 90 main jet and 140 etube thinner head gasket and what is being done with head above.
 
iatemeself

iatemeself

New Member
#2
#2
People mill more than .065" at times such as .080". As long as your piston doesn't hit the sparkplug you should be fine. I don't think you'll have any problems except for keeping your front wheel down! :thumbsup:
 
Adam McGillivray

Adam McGillivray

New Member
#3
#3
Before all the mods i had a 72 tooth i dropped down to a 62 now. Do you think ill notice less torque now? Or will my torque pry be the same just higher top end? And what springs should i run 18lbs or 26lbs
 
deesel

deesel

Member
#4
#4
Itll take off a little slower but the topend will be quite a bit faster. I would put the 26# springs in probly- that will let ur motor rev out good.
 
ole4

ole4

#7
#7
You do not have to unshroud the valves. Some people say the small chamber shrouds the valve near the edge of the cyl wall. Remember the way the ports are the flow is away from the chamber wall towards the center of the cylinder and the short side radius is near cyl wall so unless you are going to larger seats and valves it will not buy you much. Here is a head I unshrouded as I was going to a 28.5 intake. I used a ball end mill to do it. Before and after on the flow bench showed very little difference.
 
ole4

ole4

#10
#10
because i only run a max of 330 lift I only test to .350 in .050 increments. Next time I'm out there playing I will go till there is no increase. I am trying to set up a dwyer differential pressure guage to read port velocity with a probe. Seems to be more important that absolute flow.
 
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