Piston position

Just wondering. How far down should the piston go past the intake port? I took my intake pipe off and turned the fly wheel a couple times (the cylinder was still lubricated). And the top of the piston barely went past the port. Is this normal? Is it so the air/fuel can get quickly sucked into engine? (And when I say barely I mean barely)

Re: Piston position

Clearing the exhaust port at the bottom of the stroke is usually the goal

Re: Piston position

> Wesley Ambrosini Wrote:

> -------------------------------------------------------

> Clearing the exhaust port at the bottom of the stroke is usually the

> goal

That because the other ports are usually at or very close to the same 'level' .

Yes , all ports should be totally open at BDC .

Re: Piston position

And just barely clearing the whole thing is damn near perfect. It is as if the thing was engineered to do just that.

If you put a go fast cylinder and piston on, this is something important to pay attention to. That the piston clears the port entirely (but just barely like a mm or two) at BDC, and does not come out of the top of the cylinder at TDC.

Re: Piston position

Dirty30 Dillon /

If your intake port is showing at BDC, that's very bad.

Re: Piston position

It doesn't clear the whole thing though. I can't even see the top of the piston. It looks like it hardly let's anything in. I checked my crank and connecting rod and neither had any damage

Re: Piston position

The fuel enters the intake and goes under the piston, into the crankcase, then back up the transfer ports, coming out on top of the piston where it's pushed up and ignited by the spark, which pushes the piston back down, sucking the fuel in from the intake to start another cycle.

Re: Piston position

Here's a some handy pictures


Re: Piston position

Terbo Speghetti /

We need pics, dude. Gonna make it way easier to see what you're talking about

Re: Piston position

You know I misread the OP and thought he said exhaust port which is what I was referring to. My fault.

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