piston mods

[stewart]

yes doordie tdc  = top dead center  and each  kx 500  piston needs  the bottem cut to match exhaust booster and exh  floor with probley .050  matrial covering  exh port s at tdc  looking but that can un shroud transfers at bdc by alot on most combos witch heps flow =horse power

[doordie]

Oki,so you have to be very carefully with the radius of cutaway,so it?s still 0,05 left of skirt at TDC and doesn?t shortcircuit to Exhaust boostports?

No problem with cracks from the "new radius" of piston?
At uncut pistons,it?s thicker material round whole radius,but it doesn?t matter maybe?

The gain is more importent anyway

Steward and younggunnaz,we have to share every good mods so twostroke still rules!

[stewart]

the wiesco piston is the same thickness inthat area only stock cast piston has ribs at  the border where you need to grind

[kaw rider]

stewart
have you dyno this mod yet.

[kaw rider]

you can thank kawasaki for that deal. no wiseco new piston doesnt fix that deal.

[kaw rider]

i wouldnt waste alot of time on that deal for the kind of riding you do.

[dave916]

if u remove  any material from piston as shown in picture it will expose exhaust sub port  at TDC(cant be good}. there is only about 1mm  / .004 of piston skirt covering the exhaust and subports at TDC on a standard setup .5mm base gasket prox&other cast pistons
was recently trying to lower a barrel  {more low down power} until Larry Wiechman warned me of the problem i could encounter with exposing the exhaust ports

[dave916]

 Motorrad well spotted with that one, the motor may run faster for a while as it will running lean,  i think when kawasaki designed a racing piston they not add any unnessary weight or size anywhere ,except window mod which is common on loads of bikes kx250 etc
dont know what stewart was thinking with that first picture

,

[kaw rider]

But when the powervalves are closed the subs aren't flowing. The subs are cut back to far too, they are into the wrist pin area. Thats another big problem for a midrange motor. You can run a skirt mod like that but it takes custom parts. There are alot of 2 stroke with the skirt blocking at bdc.

[bigred1977]

hi there new to this site. i have read through a reasonable amount of threads on this site,moreso the enine tuning and modification
topics,i too am very dubiuos about this side skirt cut? i have a standard cylinder and piston etc and agree fully about the skirt obstruction at bdc,however if i were to cut the psiton to the degree suggested by stewart i would be freeporting at tdc BIG TIME as the ex subs are well exposed,with this engine i think even 1 mm off the skirt would be pondering on suspect? whats your opinion on this stewart?do you have measurements from cylinder deck to sub port floor for standard?its just i would likr to carry out this modifiaction however i really dont think it would be suitable on this engine,could you please shed some light or suggestion on this for us,thanks..

[doordie]

You are missunderstanding Stewards techtips,this piston were an example to show
how much area was covered at bdc.
You can remove "some" material at were he is pointing with blade.
Not the whole cut-out area at example piston....
I got some old used pistons with this mod,I will take a photo soon to show difference of stock and
modded.