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The transfer ports needed a small grind to match nicely so that's good, but that boost port is way off and I was hesitant to open it up to match as it needs a fair bit taken out to suit.
The Shop
here are the areas I would address, the boost port on the cyl should be ground back so the "overhang" is removed..the other areas circled and then highlighted in blue should all be "rolled" over heavily so they are round...the intake where the cyl and the cases meet at the end of where the reed block would be,(bascailly the circle closest to the piston), should get a heavy roll so the gases have a promoted "up" path. Hard to describe but you wil lsee in there.
Also, ANYTHING that gets fresh fuel should be roughed up REAL HARD, prickly to the touch, hammer, punch, tooling, etc, very coarse feeling. Anything that sees burnt gases should be polished, head, pv flapper..
The back two rear boost ports can get a little epoxy and profiled so the "hook" is removed and so the port appose each other. When the gases come up, they will shoot across the piston crown at each other to cool the piston crown and retain more charge..This is very important, the gases serve two functions, combustion yes, but cooling the crown! You will need a right angle porting tool to get in there after the epoxy dries.
The spark plug lig can be nipped down by .75mm so the plug sits even with the bowl, chuch it up in a lathe and nip away at the lug.
Your exh height shoudl be right around 27.5mm and a finished squish clearance of no less than 1mm.
If I look through my notes I will see if I can find more info, post back! looking good!
Kinda like this...
Josh. What are your thoughts on main bearings, would you run ceramic hybrids? Much cheaper are also polyamide caged bearings that I'm leaning to.
As for the bearings, I have used the ceramic coated before on a few builds, they DEF made a diff in how easy the crank spins over, feels like "buttah", (You have to say that like you are from Boston, my neck of the woods lol).
As for the polymide, I havent heard of them?
Saw them on a kart website. Going to stump up for the hybrids. I'm in deep enough what's a bit more hey?
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