02 KX 500 head gasket leak

[The Flyin Hawaiian]

I have a question about a external coolant leak on a 02 KX 500. I am probably swapping my old DR350/435S for my brother inlaws KX 500. I noticed that it has a external coolant leak around the head gasket when running. It has the optional thicker head gasket. I had this same problem on my old 88 KX 500 also. It doesnt seem to be getting into the cyl. Anybody else experiance this? Cant wait to get it!

[stewart]

toss the fiber thick gasket in trash and lap the head to be sure its flat put on a cometic steel gasket and some gray sealer around the water passeges and that will solve problem

[BDI]

If you want it to leak some more then ignore what Stewart said.

[KXcam22]

I 3rd what Stewart said. Lap Lap Lap. Easy and works great.  I start by lightly lapping the head and barrel surfaces separately using #400 emery cloth taped to glass or a super flat steel plate. Then lap them to each other using valve grinding compound.  You will have to pull the head studs but don't skip doing the barrel because of it. The trick with lapping is to go slow with a twisting motion and inspect the surface frequently. You will watch the dull grey area grow as you lap.  Hope this helps. Cam.

ps if anyone has other methods I am all ears.

[mdw471]

Great Idea!!

After you have lapped the head and barrel the first time, does it stay flat even after use? Or do you redo it everytime you change the piston?

Does the lappong correct a manufacturing short coming or does heat cycling the engine cause it to 'warp' out?!?

Mark

[stewart]

Great Idea!!

After you have lapped the head and barrel the first time, does it stay flat even after use? Or do you redo it everytime you change the piston?

Does the lappong correct a manufacturing short coming or does heat cycling the engine cause it to 'warp' out?!?

Mark

proably some of both

[kaw rider]

also when you install the stud, don't over tighten and put a 45* cut on the hole. so the aluminum doesn't roll up around the stud.

[BDI]

also when you install the stud, don't over tighten and put a 45* cut on the hole. so the aluminum doesn't roll up around the stud.

           Very,very good advice on the stud thing.
   
     I never ever use emery cloth to lap things it roles up the edge of what ever you are trying to make flat. I use valve laping compound on a piece of glass on top of a piece of granit. I clamp it all down on the work bench with rubber jawed wood working clamps and use the old school figure eight method. I don't lap them together because I figure that if it's as flat as the sheet of glass then It's good. I have never had a problem with this method and I have fixed a bunch leaks on many different things.

[The Flyin Hawaiian]

Im not sure I understand the 45* cut. Are you basically chamfering the stud hole?

[BDI]

Im not sure I understand the 45* cut. Are you basically chamfering the stud hole?

    Yes if you don't the unthreaded portion of the stud mushrooms the deck around the studs if you screw the studs in  tight

[kaw rider]

also depends on the head surface design.
when stewart cut my base it was .004" warped.