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good idea, bad idea?
Posted: Wed May 06, 2009 5:21 am
by fireblade
would it be a smart move to machine material from the bottom of the jug where it bolts up to the crankcase, to raise the deck height of the piston and increase compression? Or is there some pitfall in doing this?
Posted: Wed May 06, 2009 5:39 am
by bakaracer
its easier to deck the top.but what reason are you decking it for?
Posted: Wed May 06, 2009 9:45 am
by noiseguy
The reason guys used to do this on some bikes was to alter all the port timings. Frankly, unless you understand and are comfortable changing port timing, I wouldn't do that. Just knock the material off the head instead.
Posted: Fri May 08, 2009 3:37 am
by fireblade
what about removing material from the top of the jug?
Posted: Fri May 08, 2009 8:18 am
by noiseguy
Well, the head is easier to machine and cheaper to replace. I guess I don't see why you'd mess with the jug at all.
Posted: Fri May 08, 2009 9:39 am
by burnt_toast
indeed, head is aluminum jug is cast
Posted: Sat May 09, 2009 10:48 am
by keithw
The port timing on these is very conservitive. Machining the bottom of the cylinder will lower the ports reducing performance. Some actually spacer up the cylinder to raise the ports. The easy answer is mill the head. If you want to get fancy spacer up the cylinder then cut down the top of the cylinder the amount of the spacer. Make sure you understand what the ports are doing and the port angles before and after.
keithw