70 tccd piston port clearance

i am having some trouble getting my tccd to run, head was hitting and then when i increased the gaskets a bit(too much?) at BDC when looking down into the intake port the holes thru the piston are juuuuuust visible now. i think that is a problem.

i checked against a running tccd and you could not ever see the piston ports, BUT his piston was an aftermarket one.

i am just not sure how they work or what they do, should they clear into the intake and have an extra fuel boost, or do they just play at some other point?

there are two matching trenches in the top of the cylinder so someone tell me what is going on here, is this a boost? how does it work? :)

Re: 70 tccd piston port clearance

i used 3 base gaskets, my ports were JUST clearing also. Head still hit so i used 2 headgaskets. the best option is to get a real 70cc head and use the gasket also.

it went mid 40's with a 14mm carb and such.

Re: 70 tccd piston port clearance

I spy a high comp head with my eye.

Re: 70 tccd piston port clearance

i ran min with a single base and no head gasket

mine was 50cc kit tho

no issues..12mm carb and stock-modified pipe 37-41mph

Re: 70 tccd piston port clearance

when you look down the intake port you do or do not see the ports in the piston?

Re: 70 tccd piston port clearance

i did. a sliver.

Re: 70 tccd piston port clearance

ok, wasn't clear when i first read it if it was the same. thanks!

now i need to find me a highcomp

Re: 70 tccd piston port clearance

The idea is that you don't see the ports in the piston at BDC. If you do see them, you'll lose primary compression through the intake. Solution: Use a K-star piston (I do) or a custom made head for the TCCD piston.

The K-star piston also has boost-ports, but those are a lil bit higher compared to the TCCD piston.

Re: 70 tccd piston port clearance

which explains my compression issues, i knew it couldnt be right.

Re: 70 tccd piston port clearance

I wasn't able to see any of my top ports when I ran my 70cc TCCD. Although my ring broke and well it messed up my top booster port....so I know have a kstar on it and I still can't see anything. I think I have 3 base gaskets and a head gasket.

Re: 70 tccd piston port clearance

see that is the only problem, as i build up gaskets the piston stays in the same place, i need to find the sweet spot where it is high enough that th head doesn't hit, but low enough that the ports dont show....

seems like everyone has the aftermarket piston....

Re: 70 tccd piston port clearance

You can cut or file the head's squish band to get to where you want to be. Round files at an angle or some dremel work will get you there. Then there is the piece of solder squished between the cyl and piston to gauge the clearance trick

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