KDX220 intake modification

[NCFRC]

If anyone has ever looked at the intake port on a 220 vs a 200 , you'll see right away that it's very restrictive in design.

Has any body modified their 220 to be more like the 200 with positive results ? Still keeping good trail power.

My 220 runs OK but no where near as responsive as my son's 200.

 

[steve.emma]

yes i have on my old 220. i had the barrell off while doing a top end and decided to do some minor porting and smoothing to the intake port tract. also modified the intake bridge to have a more 'sharper' leading edge so as to help air flow.
i also used a pc pipe,power reeds, and a 35mm (200) carb. the bike was pretty quick after these mods.
speaking of weird findings with the 220 though, has anyone noticed when the head is off and you are looking at the top of the piston at bottom dead centre the edge of the piston crown partly blocks the transfer ports?? must make for crap air flow, but cant see an easy way to remedy this. poor design on kawasaki's part i guess, anyone know if the 200 is like this also?
steve.

 

[mudpack]

has anyone noticed when the head is off and you are looking at the top of the piston at bottom dead centre the edge of the piston crown partly blocks the transfer ports?? must make for crap air flow, but cant see an easy way to remedy this. poor design on kawasaki's part i guess, anyone know if the 200 is like this also?
steve.

This is not the detriment to power you might expect.
By the time the piston reaches near-BDC, 99% of the intake charge has evacuated the crankcase and has entered the cylinder. If the piston did completely uncover the transfer ports, you'd see virtually no increase in power.
I.e. that last millimeter of piston travel moves very little intake charge....certainly not enough to worry about. Glad to see that you're paying attention, though. :cool:

 

[steve.emma]

By the time the piston reaches near-BDC, 99% of the intake charge has evacuated the crankcase and has entered the cylinder. If the piston did completely uncover the transfer ports, you'd see virtually no increase in power.
I.e. that last millimeter of piston travel moves very little intake charge....certainly not enough to worry about. Glad to see that you're paying attention, though.

on my bike it wasn't just a mill im talking bout, it was more like 3-4mm. also im not saying the charge is restricted so much as the airflow is disturbed by the square edge of the piston and surely wont enter the cylinder in the manner its designed to. i know on some racing engines tuners modify the edge of the piston as as to avoid this situation.

 

[mudpack]

im not saying the charge is restricted so much as the airflow is disturbed by the square edge of the piston and surely wont enter the cylinder in the manner its designed to.

All stock two-stroke engines have a square piston edge that affects intake airflow...at all openings, not just near BDC. The "disturbance" is moot. The engineers are aware of this and have taken it into account: the intake charge enters the cylinder just as it was designed.
Modifying the piston to "compensate" for this could just as easily do more harm than good.
Glad to see you are thinking.


Mud



________________________________________________
I'm not an aerodynamicist, but I play one on the internet.

 

[NCFRC]

Besides the center bridge , has anyone ever opened up the intake port similar to the 200 ?