Intake & Porting ???

[kujoskennel]

    I'm working on a GY6 rebuild. I've Installed a 50mm bore kit. The Stock carb just isn't the preformance i'm looking for, so I ordered a PWK 24mm carb & manifold. I know I need to port my head bc my new manifold is 26mm. i'm having trouble finding a 26mm spacer and gasket. Shld I just order a stock 150cc spacer? 

[GrumpyUnk]

If using the plastic spacer between carb and cylinder head, why not use some tools to enlarge the opening so it matches the outlet of the carburetor? You could also adjust it to match the diameter of the intake port of the cylinder head, more or less tapering from larger to smaller. That would be a better match IMO to just plopping a larger diameter w/o doing any matching.
tom

[gapplebees203]

I agree with Grumpyunk^^ just upsize the hole on the stock spacer, can use a drill an a step bit, oh an probably something to hold it still with. Id suggest a vise if possible but if not, a block of wood an a few screws will work too. Just screw it down to the block an drill it out tell its the size you want. Can probably get a step bit from a hardware or autoparts store for under $20. And you can use it again in future projects.
An as for the porting the head, thats what im about to do to my scoot. I have a 52mm bbk with a big valve head, being fed by a 28mm pwk. So 28mm to 17mm is a drastic drop.

[GrumpyUnk]

Didja ever hear the phrase: 'Lipstick on a pig."? Seems doing all this work to feed a quite dimunitive sized piston/cylinder may be kind of like shining the chrome on a '59 Studebaker Lark. VI. Auto. 2-door sedan.
Why not shine up a '63-64 Impala 2 door hardtop? 327 4-speed?
But I digress.
Have fun porting, but don't get carried away. Not all that appears to be blockage should be removed. Sometimes what looks to be an impediment actually causes a good airflow, so be wise and careful removing material.
Eric Weingartner here:
www.youtube.com/watch?v=EFflEhZVYog

Difficult to see what he's referring to, so watch closely. Just a thought.
tom

[gapplebees203]

My main idea is to widen the intake port at the mouth an maybe remove casting defects on the way to the valve port. I just dont want it to go from one size to a smaller size with a wall. My idea is to make it kinda like a funnel. I understand this is a delicate process an removing too much can actually impead the airflow.

[jackrides]

What they said plus smooth transitions are key. Smooth but not polished in an intake. Reasoning is that a little surface turbulance increases atomization of fuel.