CG250 Head - A Closer Look.

[Weldangrind]

Do you plan to polish the exhaust side?

[BlackBike]

Mega... Many have threatened to go thru with this but never reported back here. I Guess you are one of the few of us that are not so tight fisted. This looks interesting.

[Megadan]

Originally Posted by BlackBike

Mega... Many have threatened to go thru with this but never reported back here. I Guess you are one of the few of us that are not so tight fisted. This looks interesting.

I have been accused of having more dollars than sense... but yes, I plan to follow through with this. Having 2 bikes affords me the luxury of being able to do this kind of work while still being able to ride. Plus, I like to tinker.

[BlackBike]

Originally Posted by Megadan

I have been accused of having more dollars than sense... but yes, I plan to follow through with this. Having 2 bikes affords me the luxury of being able to do this kind of work while still being able to ride. Plus, I like to tinker.

Well so far, your toy signature seems pretty sensible.

[Megadan]

Originally Posted by BlackBike

Well so far, your toy signature seems pretty sensible.

It only appears that way.

[Megadan]

Originally Posted by Weldangrind

Do you plan to polish the exhaust side?

I plan to port both intske and exhaust and polish the exhaust side, yes. I also plan to smooth the edges of the quench ring and polish the combustion chamber,.

[Weldangrind]

Originally Posted by Megadan

I plan to port both intske and exhaust and polish the exhaust side, yes. I also plan to smooth the edges of the quench ring and polish the combustion chamber,.

I'll be following with great interest. I've often considered polishing the surface of the piston as well. I've noticed that stock pistons are typically quite a rough casting on the combustion surface, whereas the rest of the piston is nicely machined. I've also noticed that aftermarket pistons are generally machined on the combustion surface as well as the skirt, etc. This leads me to wonder if there might be two benefits to polishing the combustion surface; one is the theoretical efficiency increase in moving fuel/air and exhaust, and the other is resistance to carbon build-up. What do you think?

[Megadan]

Originally Posted by Weldangrind

I'll be following with great interest. I've often considered polishing the surface of the piston as well. I've noticed that stock pistons are typically quite a rough casting on the combustion surface, whereas the rest of the piston is nicely machined. I've also noticed that aftermarket pistons are generally machined on the combustion surface as well as the skirt, etc. This leads me to wonder if there might be two benefits to polishing the combustion surface; one is the theoretical efficiency increase in moving fuel/air and exhaust, and the other is resistance to carbon build-up. What do you think?

From my personal experience, polishing does help resist large carbon deposits forming, but you will still get a thin layer no matter what you do, because even the best polishing job possible still has microscopic grooves for carbon to cling to and build up on. I did consider pulling the piston and doing that kind of work, but that may be for a later date. I will do what I can with the head, and put on a new head gasket.

That said, it would be kind of fun to go all out on one of these motors, but even I have my limits on how much I want to spend. What I would personally do is send the piston and head off to Swaintech, have their ceramic coating applied to the piston top, combustion chamber, valves, and exhaust port, and their low friction skirt coating done as well. Since it's a one cylinder engine, the cost wouldn't be too horrible. This does amazing things for keeping aircooled motors run a little bit cooler, since more heat is retained in the chamber during the combustion process. Current prices for that treatment would be $52.50 for the piston, and $54.50 to do everything to the head. So...$107 bucks.

I did consider seeing if I can find some undercut stainless steel valves that would work with this motor and have a shop install and hone some bronze guides for it. Again, not entirely necessary, but an idea. I would definitely consider this more if I were to bump the compression up a point to around 10:1. I really don't want to do that personally, at least not without some way to control the ignition timing.

[humanbeing]

Originally Posted by Megadan

...ceramic coating applied to the piston top...

Coated piston (<$5) is the standard item in workhorse trike...