In Australia we now have a good range of fuels, so I would like to bump up the compression by shaving (milling) the head. I have a rev pipe and are chasing more mid and top end power. Has anyone tried this simple mod and got any stories to share.
I have just put my 220 together this afternoon, new cases, replated barrel by US Chrome and I took 0.5mm off the head using a 4 jaw chuck in the lathe. I have been told this is fairly conservative, with guys who raced them new at the Australian ISDE in 99 taking up to 1.5mm. However one blew the gearbox apart and the other dropped the skirt off the piston (as typical of standard 220 pistons), so maybe they pushed it a bit far. I took 0.5mm off a KTM 250 EXC 6days model before the ISDE last year, with the owner saying that it gave a noticeable amount of extra grunt. I will see if I notice a difference in my KDX tomorrow. I run race gas and full synthetic oil at 40:1. FMF rev pipe, flywheel weight, V Force 3 reed block.
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