2000 KDX 220-Should I polish the ports?

[xr400forever]

I have the ttop end apart for cleaning and a new top end kit. I noticed the intake side had sharp casting lines on the intake side so I ground these away(very carefully with a Dremel). Now I am wondering if it is any use to polish the rough surfaces in the ports. One person told me to only polish the exhaust side, Can anyone shed light to this situation?

 

[fatty_k]

Polishing has no positive effects to the overall power. Its is mearly cosmetic.

 

[canyncarvr]

I disagree, kinda.

Not too often is a polished surface on an intake desireable. To that end it may well be UNdesireable.

There's a lot to porting. Not to make it smoke, mirrors, witches' brew and potions, but if you don't know what you're doing, chances of making things worse is most excellent!

Ask EG how many 'practice' cylinders he's used over the years........

Because you asked for opinions...I offer mine. Leave it alone!!

 

[Racerjoey1]

I have heard not to polish the intake side because the casting marks help the air to tumble and atomize the fuel better.

 

[gwcrim]

Not that I've ever ported a two stroke, but I have done a few 4 strokes..... The only thing a first timer should do is to remove the obvious casting ridges and smooth up very rough surfaces and sharp edges. Yes there should be some texture to promote fuel atomization, but not as much as one might think.

One major area of improvement is the combustion chamber. The more polished it is, the less likely detonation is to occur. This allows higher compression and more ignition timing.

Also, machining the squish band to mate perfectly to the piston top is a great move. The squish band clearance should be about 0.030 evenly all the way around. This helps eliminate detonation as well.

 

[Boot]

Racerjoey1 is spot on. A smooth surface on the intake side allows fuel droplets to stick because the airflow is always zero at the contact layer for any fluid (such as air). A slightly rough surface creates turbulence which breaks the fuel droplets up better.

As gwcrim says, just remove the big casting imperfections, but leave the surfaces rough.