Head milling on a KDX220R

know_fear · Mar 23, 2003

My 2000 KDX220 has been suffering from leaking head gaskets so I thought I should use some wet/dry paper on a piece of glass to ensure the head surface is flat. What are the risks and benefits of removing .010" of material to increase my compression ratio. My current squish is .095" and pump gas here is said to be 94 octane. I'm running an FMF pipe a Wiseco piston and the RB enlarged carb. Any comments are welcome.

Robcolo · Mar 23, 2003

It will take you a while to remove .010" by lapping. I milled mine about a year ago and I think that I removed .028". A squish clearance of .095 is way excessive -- an d maybe one reason that the 220s overheat. Squishes in the range of .040 - .055 are more realistic. The octane requirement isn't dependent on the squish clearance but on the final head volume. The stock 220s have a pretty low comp ratio and removing .010 won't make much difference.

know_fear · Mar 23, 2003

So how did your power feel after taking off .028"? Would it still run fine on pump gas?
You're right about lapping being labour intensive. It took me quite awhile to remove .010" even using 60 grit emery cloth. I won't get a chance to try the bike out until next weekend but from what you're saying I may not notice anything.

Head milling on a KDX220R

know_fear

Robcolo

know_fear

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