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2012 sx time for a top end. gasket thickness?

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Hey guys.  bought a 12 250sx used.

ive put 30 hours onto it already myself.  it seems a bit weak at times.  probably time for a new top end for what its worth.

 

for the cost.. ill prob just go OEM.  its cheap.  this kit here:  54830007300 I  (DO I NEED "I" OR "II"?)

 

http://www.ebay.com/itm/112122182915?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

then I just need new gaskets basically?  whats with all the different thicknesses... which one do I want/have? how do I tell without taking it apart first?

 

http://www.ktmpartspro.com/oemparts/a/ktm/524b9d21f8700231ac49aa51/cylinder-cylinder-head

 

 

Gasket Cylinder Base 0,2Mm

Gasket Cylinder Base 0,4Mm

Gasket Cylinder Base 0,5Mm

Gasket Cylinder Base 0,75Mm

 

anything else I should know about/look at/replace while im in there besides the obvious gaskets and o rings?

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Measure the bore, but I would assume that you'd be looking for a B size Piston.

 

Measure the base gasket stack, and purchase them to match if you're happy with it.  

 

Purchase your top end from Andrew Cooksey.  He will set you up with everything you need at a better price, with much better service.  He will make it easy for you.

 

https://www.cookseycrank.com/top-end-kits

Edited by poldies4
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I've read that the factory stock gaskets are a stacked .2mm and .4mm. Slavens recommends that if you're running his Mule head below 4k, during rebuild, go with a .5mm, if above 4k, go with a .4mm. Even tho I don't run a higher compression Mule head, I decided to get the .5mm, as I'm below 4k. But I do see higher when I travel to go ride. I'm hoping the single .5mm will be fine.

My 2013 300 has 186 hours on its original piston and still going strong. Showing a little blow by but nothing major, but was going to do a top end just to be safe before the summer riding season. Haven't got the cylinder off to measure it yet but from everything I've read, for a cylinder with that many hours on it, a stock "A" piston will be too sloppy, so ordered the "B". The difference between them is like 5 ten thousandths of an inch (.0005") or something.

I just recieved the kit from Cooksey, along with adding the PV orings and EZ clips.

Edited by Trailryder42
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awesome!!! very good info.  especially about the B piston.

 

I dont want to take it apart, and then order.  id like to order, go to work for 14 days, come back, have parts waiting and have it all done in 1 night.  tear down, to break in.

 

ill totally get rid of the ebay one and look into the B kit from Cooksey.

 

186 hours is damn good to hear... why did you go so long on a 2 stroke though??? I mean I like pushing my luck and parts, but 186 is up there!!!

Edited by cdf450

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2 hours ago, cdf450 said:

 

186 hours is damn good to hear... why did you go so long on a 2 stroke though??? I mean I like pushing my luck and parts, but 186 is up there!!!

I'm an older rider. Don't race, just trail ride. I don't think I ever see top end throttle, let alone ride on the pipe. Was going to let it go to 200hrs but decided, eh, going ahead and replacing it might prevent ruining a planned trip to Colorado or the like.

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If you are going to use the stock piston, do yourself a favor and by the easy clips from Munn or Slavens.  Those stock clips can be difficult.

I prefer forged pistons myself.  If you want a "no fuss" gasket kit, the Tusk brand is nice.  It comes with a .5mm base gasket that will work just fine.  

 

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