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There ya go! That's how to do it.

It shouldn't be a problem as long as the cylinder is good and there aren't wear marks. Did the old piston rings scratch the cylinder walls?

Hoca parts are usually synonymous with racing, so the dome is there to increase the compression. You might not like the extra compression as it can lead to harder starting and a tighter tolerance with the a/f mixture. To compensate, people add a 2nd base gasket to lower the compression.

Very nice. Not bad at all.

That head doesn't look bad at all. I bought my NCY head because it was the size I wanted and it cost the same amount as that one.

Yeah, people don't know about the spring bind or valve float. But for most of people's riding habits here, it isn't an issue. We are talking about regular street riding and reliability.

I wouldn't port and polish the head unless you have done it before....but, it isn't a bad idea to clean up the casting from burs. You could make the head flow worse if you don't know what you are doing. If you do choose to do it, buy a kit with different grits. Think very very mild grits so you don't over cut. Or you can try the de-burr kit. Also, practice on the stock head you won't use.

Personally, I have done porting on half a dozen items from intake manifolds, exhaust manifolds, and heads, all for cars. There is a lot of time and calculations that go into porting. You have to scribe matching components and gaskets, you have to mark the thin areas of metal, and you have to make sure that your porting doesn't make the flow worse. You want the straightest bends with least friction. Larger ports aren't always better, especially if it creates a tighter bend. I didn't port my head because I didn't have the bits ready and didn't want to remove the valves as it is already assembled. Mine is a street rider, not track racer.

I was also looking at that kit, but I purchased a 58.5mm NCY kit because the piston skirt goes almost all the way around. If you look at the "high compression" or "performance" pistons, you will see the piston skirt is cut out at the wrist pin sides. That means the piston will rock more in the cylinder. More rocking leads to more wear. I was looking for durability and longevity. If you are doing a drag bike or plan on rebuilding in less than normal wear time, then get the lighter high compression pistons.

I also added an NCY 58.5mm head. If you do the 26mm carb, there are choke points in the spacer and the stock head. They both measure at 24mm.

Now, as far as flow, yes these can be restrictive, but another way to get more air and fuel is duration. That is where a camshaft will work well.

I haven't started the engine yet with the bbk upgrades, will probably finish up the build by tomorrow.

Is it just the bbk or do you have an intake or exhaust as well?

For those who have done 50mm bbk's, they usually use a higher main jet than #. You might need a #-#92 if all you have is the bbk. To richen the mixture, you need to move the clip to the lowest setting, so the needle actually sits higher. 40 pilot jet is too big, good hting you changed it back.

Also, have you checked the spark plug?

So we can better help you and get a clearer picture, please list your mods, how it behaved before the bbk, and other history while doing the bbk.