Still confused about porting

[noah9988]

Like Karl said go slow, you want to remove any slag or high spots but don’t raise or lower the ports, you can widen them. Raising or lower requires a degree wheel to get right. Cleaning it up is probably all you need to do.

Yeah I'm going to be careful and not remove too much. The transfers on the blown up jug I have are absolutely horrendous. Hopefully I can work out a technique to get em cleaned up.

 

[Karl Snarl]

I use a 45 degree pencil die grinder now, much easier to do. Cost me about $20 bucks and a hotdog compressor will run it easy peasey.

 

[Regalgse00]

Yeah I'm going to be careful and not remove too much. The transfers on the blown up jug I have are absolutely horrendous. Hopefully I can work out a technique to get em cleaned up.

I use a degree wheel to do porting. It’s not that bad with a wheel once you set up the wheel correctly. I’ve been doing my own porting as well. I have a pk80 with a mz65 and I made my own window piston with a g2 reed and made a boost port as well. The bike hit 42 before with no porting snd now with porting it hits 48mph and I weigh 170lbs.

 

[Regalgse00]

 

[Regalgse00]

 

[Chainlube]

Here is pic of my intake side port at tdc, all I did to this port was clean casting slag/flaws from port. Can some of you professionals tell me if this is ok? Or did I already mess up?View attachment 158506

That's fine, you can trace the port on the piston skirt with a sharpie and then file off the sharpie mark.
Most of all you want the entrance to the cylinder to be beveled, that way the rings won't hang up on any sharp opening.

Leave the intake a little rough for turbulence and polish the exhaust for none.

 

[noah9988]

Thanks for the advice and pictures, guys. My last yd100 got up to 38 without any porting (and hauling my fat a**). Hopefully I can get 40 out of the new one (and not explode the internals).

 

[Regalgse00]

I’ve seen on a few of the engines I messed with that the wrist pin is a tad to long and won’t let the c-clip sit flush. So I had to grind the pin a little bit for the clip to sit in there nice. I had that happen to me on my first bike build

 

[hazmat]

My wrist pin circlip in my yd 100 decided to blow out (surprise, surprise) and my engine proceeded to grenade itself. I got another one coming with cw10 circlips. I want to port the head but even after all the reading I've done I'm not confident I know what I need to do. I have my old head that I can practice on. My understanding is that you want to make the port bigger. That confuses me because the ports are kind of cone shaped, if you imagine them from the top. For example, the hole of the intake port gets smaller as it approaches the combustion chamber. The exhaust port is the same way. Where do I take material from?

I'm also wondering about intake and exhaust gaskets. The hole in the gasket is smaller than the port. What should I do about that?

i hope you mean port the cylinder. porting the head is a real skill left to specialists with cool toys that you probably dont have access to commonly.but porting the cylinder has some things to watch for like stay between the piston ring holders to pins you will see on the intake side if you go past it compression loss will happen. dont be so concerned about damaging your cylinder the cost is not bad for stock and when you get it down you can start doing sleeved cylinders.have more confidence in yourself and have fun
ps grind away flashing and the gaskets you speak of to match (port matching)

 

[Karl Snarl]

i hope you mean port the cylinder. porting the head is a real skill left to specialists with cool toys that you probably dont have access to commonly.but porting the cylinder has some things to watch for like stay between the piston ring holders to pins you will see on the intake side if you go past it compression loss will happen. dont be so concerned about damaging your cylinder the cost is not bad for stock and when you get it down you can start doing sleeved cylinders.have more confidence in yourself and have fun
ps grind away flashing and the gaskets you speak of to match (port matching)

A lathe or mill if you wanna change chamber shape. They make special bits, but if your good you don't need them.