two stroke top end rebuild

[Kinger118]

I am doing a top end rebuild on my kx125 just wondering what gasket kit i need to get? Do ineed the one that comes with the oil seals or can i get the one that comes without them

 

[eagles22793]

I would get the one with the oil seals just to replace everything I can while I am in there. I would recomened the moose racing top end gasket kit because it comes with a thicker bottom cylinder gasket for more perfomance and is cheap.

 

[Kinger118]

i am sponsered by vertex pistons so i am going to get it from them as well as the piston kit

 

[IndyMX]

I would get the one with the oil seals just to replace everything I can while I am in there. I would recomened the moose racing top end gasket kit because it comes with a thicker bottom cylinder gasket for more perfomance and is cheap.

A thicker base gasket for more performance? Please explain..

 

[Dirtdigger04]

I heard the Cometic gasket kits are pretty good.

 

[FruDaddy]

A thicker base gasket for more performance? Please explain..

+1 I would love to know how that thicker gasket alone will improve performance. I understand that there will be a very minute adjustment in port timing which would make an equally minuscule improvement if the top of the cylinder were milled down by an equal amount, however, it seems that the gain will be neutralized by the enlarged squish area that has decreased the total compression. Since I have no engineering background, I accept that I could be way off base on this one. Please provide evidence if I am. My greatest argument is that I have run .2, .3, and .5mm base gaskets in my son's 85 with zero noticeable difference in power, although KTM makes a tool that will help me to set the timing properly with the various gaskets.

Wow, that sounds a little like somebody else around here, I could be wrong, so I won't name names. He would not be so nice.

 

[IndyMX]

, however, it seems that the gain will be neutralized by the enlarged squish area that has decreased the total compression.

That's what I was thinking...

 

[whenfoxforks-ruled]

Too funny Fru. I believe the it is the changed port timing along with the lowered compression, and ever so little, together makes better power on top? Some are that way. I do not recall ever hating a KX125 power band. They have seemed to pull hard off bottom to infinity. In Eric's book on hop ups, the 98 to 00 has too high of compression, for example. Yet another needs head work and cutting the base? Get the book, or box up your top end, and send it to Forward Motion, http://www.eric-gorr.com/ , tell him what and where you want it. Those bikes did have a lot of issues with the oem plating, Eric fixes that also. Vintage Bob