Performance mod - Polished Head???

[dodge dude94]

dodge dude you cylinder head looks pretty rough there, to be honest i don't think theres much need to polish it but a bit or work with some finer sandpaper might help a bit. Also if you looking for performance increase there are plenty of mods out there that don't take much time and can yield beneficial results. If your looking to modify the head for more power try making a better squish band.

I lapped it a bit a couple weeks ago. I'm waiting until I get my parts order in because I'm going to be pulling the entire engine and working it over.
What do you mean by making a better squish band?

Sand your combustion chamber down a bit by hand, to get most of the paint and/or roughness off, then take a dremel tool and use a BRASS wire brush, that will bring out a real nice smoothness.

Never thought about that. I will remember that. Thanks.

 

[SpeedWizzard]

The squish band is the part where the head ALMOST comes into contact with the piston, the fuel is forced into the small cavity in the center to burn beter and more effectively. that pretty much sums it up but try downloading the 2 stroke tuners handbook and it will explain pretty much everything. (i gave a pretty crappy one)

 

[dodge dude94]

The squish band is the part where the head ALMOST comes into contact with the piston, the fuel is forced into the small cavity in the center to burn beter and more effectively. that pretty much sums it up but try downloading the 2 stroke tuners handbook and it will explain pretty much everything. (i gave a pretty crappy one)

You talking about that little ridge on the outside of the combustion chamber that make an indention into the head gasket?

 

[Toadmund]

That was my thinking too, but I guess it is not.
It's not the part that squishes the gasket, it's the part that squishes the fuel mixture. It squishes the fuel mix, so that it is forced and compressed into the spark area.

 

[MotorBicycleRacing]

I lapped it a bit a couple weeks ago..
What do you mean by making a better squish band?

Never thought about that. I will remember that. Thanks.

Below, you can see a re-chambered head that is shaved down and a correct
shaped squish band added to a stock China Girl head.
Makes a great sleeper motor and they are only made by Arrow Motorized
Cycles.

Bottom side view cut away shows the squish band and clearances from a pic
on Manic Mechanics website.

Polishing a stock head without doing these mods is a waste of time that will
have no performance gains.

 

[dodge dude94]

Below, you can see a re-chambered head that is shaved down and a correct
shaped squish band added to a stock China Girl head.
Makes a great sleeper motor and they are only made by Arrow Motorized
Cycles.

Bottom side view cut away shows the squish band and clearances from a pic
on Manic Mechanics website.

Polishing a stock head without doing these mods is a waste of time that will
have no performance gains.

So how do I get there?

 

[MotorBicycleRacing]

So how do I get there?

Huh? lol
Get where?
You mean how do you modify your head to be like the Arrow Motorized Cycles re-chambered head?

Chuck it on your lathe and turn it down the gasket mating area then turn the right angle and width of squish band to match the dome of your piston.

Then deck your cylinder to give you the the right clearance of your piston to
the squish band of the head.

No big deal right?

Or you could take the easy way out and buy one off Arrow for $35?

 

[dodge dude94]

Huh? lol
Get where?
You mean how do you modify your head to be like the Arrow Motorized Cycles re-chambered head?

Chuck it on your lathe and turn it down the gasket mating area then turn the right angle and width of squish band to match the dome of your piston.

Then deck your cylinder to give you the the right clearance of your piston to
the squish band of the head.

No big deal right?

Or you could take the easy way out and buy one off Arrow for $35?

Yeah, that.

Lathe, I don't have a lathe. So I guess I'm just gonna have to smooth it our more and lapp it. Cuz I don't wanna spend $35, too cheap.

 

[MotorBicycleRacing]

Yeah, that.

Lathe, I don't have a lathe. So I guess I'm just gonna have to smooth it our more and lapp it. Cuz I don't wanna spend $35, too cheap.

Smoothing more will do nothing and no one else can see that shiny
polished combustion chamber that will soon be coated with carbon.....

Reducing the the combustion chamber volume by lapping very little material
off will also have very little to no effect because you aren't removing much.

Another Major problem with the stock China girl head is that there is not enough
mass and cooling area if you start raising the compression and performance from
stock with other mods like an expansion chamber, porting carb etc.

Check out this off the wall head from CR Machine.

Copper squish band for enhanced cooling!
May be available for hardcore racers in the future.

 

[dodge dude94]

Smoothing more will do nothing and no one else can see that shiny
polished combustion chamber that will soon be coated with carbon.....

Reducing the the combustion chamber volume by lapping very little material
off will also have very little to no effect because you aren't removing much.

Another Major problem with the stock China girl head is that there is not enough
mass and cooling area if you start raising the compression and performance from
stock with other mods like an expansion chamber, porting carb etc.

Check out this off the wall head from CR Machine.

Copper squish band for enhanced cooling!
May be available for hardcore racers in the future.

Huh. My thought for smoothing the combustion chamber is so that way carbon CAN'T stick quite as well. Reason being is that carbon sticks to a rough surface more so than a smooth (relatively speaking) surface, which is one reason why guys port the exhaust ports on these little engines. And I figured lapping the head wouldn't make a huge difference, but I know that every little thing else. I've already got a cooler spark plug to deal with some of the detonation issue. Damn Texas heat.

That head looks nice, but I can't see spending that sort of money on a "dirty" Chinese engine. :\