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Kx450f warped head?

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Ok guys, picked up a 06 kx450f. Was blowin white smoke and I thought it was a cracked head. Pulled the head and can't find an cracks or imperfections that's would cause water in combustion chamber. The gasket was pretty bad. Was all in one piece. Any thoughts??

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Head should be fine to use for 100s of hours. Sand the head surface flat and reassemble with a new gasket. 

 

To sand the head you tape a piece of 320 wet sand paper to a thick flat glass plate. Sand in a figure 8 motion using even pressure. Draw some pencil on the surface to check how flat it is.  If badly warped then revert to 240 grit.  Then repeat using finer grades. I finished with 400 and today it runs great. It only takes a few minutes on each grade of sand paper. I used water on the paper, and left all the valves installed in the head.

 

Thoroughly wash and heat dry the head.

 

Also clean the cylinder bore using soapy water and a scotch brite pad, then acetone on paper towels.

 

Reassemble with the gasket surfaces spotless clean. I reassembled mine using a very thin layer of copper coat sealant on the gasket.

 

20130504-IMAG0684_zps8c5ca131.jpg

 

Take special care torquing the head bolts, and cam journal bolts.

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sand the head per previous post but I advise spray adhesive to glue the paper to the plate. I tried taped first but found the paper ripples and you round the edges of the head. glued down and you get perfectly flat right across the face

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sand the head per previous post but I advise spray adhesive to glue the paper to the plate. I tried taped first but found the paper ripples and you round the edges of the head. glued down and you get perfectly flat right across the face

Interesting idea. Which spray adhesive did you use?

 

Problem is I went through a lot of fresh sheets. I'm into spending a few $ more on fresh sheets of sand paper, to save a lot of of sanding time, and get a nice flat cut surface.

 

I didn't have any problem taping all four sides of the sand paper to my glass plate. I'd just peel up, dry it and tape down a fresh one.   I used 2" wide gaffa tape.

 

With spray adhesive, can you peel a dead sheet up, then lay down fresh sheets easily, without the glass getting bumpy?

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I purchased a box of glass mirror tiles, 240 and 400 wetndry sandpaper, sellies contact spray adhesive (Bunnings) I only used the one sheet of each and would have just used another tile if necessary (cheap enough). 

With the paper taped I thought I had no issues getting flat but this proved incorrect. I didn't notice the rippling but was there,

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Is it necessary to do the jug as well?

Maybe. However I sanded mine on 400 with some ink on the alum surface, being the easiest way for me to precisely check it. And it was flat. The head was certainly warped.

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I did the jug as well to be sure. As Numroe said ink on the alloy surface lets you know how your going, I just coloured mine with black texta.

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I did the jug as well to be sure. As Numroe said ink on the alloy surface lets you know how your going, I just coloured mine with black texta.

Good work.  Was the top of your cylinder flat?

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Neither was flat, head was worse though and this was a brand spanker. Leaked from the moment the bike started after install.

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