300/440/550 crankcase cleanup? can someone shed some light on it for me?

[tsha9882]

Hello everyone, I have a 94 550sx that i'm wanting to put a weisco 77mm kit in but it says i need to have the crankcase cleaned up, was wondering if someone could tell me what this means? Is it something i can do myself or could the shop I'm having do the bore do it? Any help is much appreciated, thanks.

 

[tsha9882]

Anyone???

 

[gtgoat]

No idea, Try calling Wiesco. They've been helpful for me in the past. It might be as simple as having it washed out.

 

[the flying dutchman]

im not an expert on this there are alot smarter people about this on here than me but i have a 1990 550sx that im in the same shoes and from what i understand what you have to do is that the top of the crank as to be enlarged a bit to handle the bigger pistons going up and down the way they are set up not it does not have enough clearence to go down the full amount its enlarging it a bit..

hope that made since and i would suggest letting the local kaw shope do that im sure they will rape u in labor rate but its better doing that then spending almost 400 and tearing the top end up again.. if nothing else i wouldnt do it but look at sbt (short block technologies) and just do a moter exchange for i think around 600 depending on the one you get.. you are going to start off stock but have a year or two warranty. hope this helped dude

 

[cookn]

crank case clean up means you have to bore the top part of your top case because the bottom of the piston comes out of the cylinder and into this area. I believe it measures somewhere around 76mm. So that means the top two bore sizes would not fit causing major engine failure. Your machine shop will be able to bore this out no problem. I bored mine to 78mm.

 

[tsha9882]

Thanks dutchman and cookn, thats what I thought but just wanted to be sure, unfortunately looking like the bigger bore is going to have to wait a while.