3rd port in piston above 2 smaller ones anyone seen it

[dadofethan47]

I have a piston and cylinder combo that it has 3 ports on intake side of piston. It has the 2 vertical ports on lower half of piston. and 1 port horzontal above other ports. The cylinder also has epoxy in one of the ports on intake side but has 2 ports on intake side inside of cylinder. Just wondering if anyone has seen anything like this? the combo is very fast but need to get it bored out. and nicalsiled. any help would be great. thanks

[don bassani]

Perhaps small hole is to aid lube to wrist pin bearing.

[dadofethan47]

Originally posted by don bassani
Perhaps small hole is to aid lube to wrist pin bearing.

It is a big port about the same size as the vertical ports. I put new piston in that cylinder with just the two ports and it ran like crap. wouldn't hardly rev. Used mill and cut same port in new piston and then it was ripping. The dyno sheets I have say it is running 21.4 hp @ 11400 rpm Just hoping I could find someone that has seen this before.

[don bassani]

Hetrick would probably know

[Logan #34's Dad]

Originally posted by dadofethan47
The dyno sheets I have say it is running 21.4 hp @ 11400 rpm Just hoping I could find someone that has seen this before.

Is that a 70cc or 90cc? either way, that's some impressive numbers......
I'd dig in the research of who built the motor.....

[dadofethan47]

I know who did the work but he is no longer with us. I have seen some other cylinders and pistons done like this also. But never thought nothing of it because I could get these cylinders. I don't know if the guy that did my cylinders showed the others or the others showed him. what ever it is the thing rips. I just don't want to start all over on r and d to figure out the clutching and all that for new cylinder design and this is a 90cc I bought it this way and if it's not broke don't fix is the way I see it. Here is a list of what is done to motor if it helps.
Fully ported race cylinder nicasiled. extra port in piston, 180 high comp head,needs VP C12 fuel 28mm carb,Koso intake, hetrick genII pipe, stuffer crank. cut flywheel to make lighter, pvl ignition. titanium bolts in engine. it won't let me add pics of piston and cylinder. so someone could see what I am talking about.


Here is you tube vid
http://www.youtube.com/watch?v=RV02tfHK8kA&feature=related heat

[Logan #34's Dad]

I notice that it's Aircooled........ 50cc?

[dadofethan47]

Originally posted by Logan #34's Dad
I notice that it's Aircooled........ 50cc?

90cc.
I have another motor I could try diff cyl and piston setup. but need to get overange kit for it. So I could just swap out motors without messing with clutching on the one that is in there now.

http://www.youtube.com/watch?v=RV02tfHK8kA&feature=related heat race

[zach R 7x]

I used to have a 107cc motor built by Chris Crump , he used to run a mini quad shop out of Fremont Ohio. He was taught by some gocart guys how to build motors. The motor I got from him had this same hole milled in the piston , I still have the piston somewhere, but cyl is long gone. He explained to me what it was for , but I can't really remember all the technical terms for it. Not for certain , but I believe it had to do with compression and dumping the excess gas back down to the crank case. I could be totally wrong , it was a long time ago. We never ran the motor on a track( it was way illegal for CRA), I did ride it down the road a few times and it was crazy fast!

I bet Rich Hetrick will know what it is.

[machwon]

Adding another port to the top intake side of the piston will help with cooling the piston crown and wrist pin bearing. The piston weight loss would be small, but lighter is better as long as it survives. It also has the effect of shortening the effective runner length for the boost port (unless their plugged off) depending on where the hole is at and where everything lines up.

[bloodswet&gears]

Do you have picture of them?

[dadofethan47]

It says file is to big to upload. But I did talk to a guy today that has seen porting like this on scooters and The way he explaned it is that it helps with crank case pressure and advances the port timeing to let fuel in sooner. And also keeps cylinder temps down too.