Pics for sicivicdude

[Prime]

Here you go, all the pics you requested.

Cometic



Possibly shaved head?


Crankshaft


This says "H"


"43G"


More crankshaft

 

[sicivicdude]

That's an OEM gasket. It does looks like multiple layers but it's not. It's kinda gooey sticky on both sides to take the aluminum REALLY well.

That appears to be a stock stroke crankshaft. You'll have to measure the stroke before you put the head down with a depth caliper but it looks like a stock stroke crank. It's clean dude top end gasket set and rock out!

 

[Prime]

Sweet. Thanks! I just wasn't sure about the crank. Probably should've looked 10 feet to the side at my other bottom end and the other crank to see about the "serial numbers" on the connecting rod. I'm fine with it being stock stroke, I just thought it'd be pretty cool to have a stroker in there.

 

[Blaner]

that head does look a bit shaven if im not mistaken!

 

[Prime]

that head does look a bit shaven if im not mistaken!

That's what I thought!

 

[Prime]

Either that or I have the one head ever made by Yamaha where the casting is actually clean...

 

[sicivicdude]

If anything, that's a stock yamaha head with the mating surface shaved slightly. It looks like a stock combustion chamber.

 

[Prime]

Yeah, I'm not sure what was done with it, this is the first time I opened up this motor.

 

[sicivicdude]

Measure the "lip" between the mating surface and the start of then quench area.

 

[Prime]

Alright, I will when I get back home. I am about to leave for work.

 

[Prime]

Measure the "lip" between the mating surface and the start of then quench area.

It's five thousandths.

 

[sicivicdude]

Then that head mating surface has been shaved. Yamaha heads have in the order of .8mm or about .020" difference between the mating surface and the start of the quench area.

Shaving a head increases the compression ratio slightly (simply reducing the volume the trapped charge has to be squished into) but a real gain in power would come from having that head redesigned with a proper squish band and hemispherical combustion chamber.

 

[Prime]

Then that head mating surface has been shaved. Yamaha heads have in the order of .8mm or about .020" difference between the mating surface and the start of the quench area.

Shaving a head increases the compression ratio slightly (simply reducing the volume the trapped charge has to be squished into) but a real gain in power would come from having that head redesigned with a proper squish band and hemispherical combustion chamber.

Sweet, thanks for the info.