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Discussion Starter #1
Hey there. Bought a 2000 400ex and seller said it was bored 40 over with a stage 3 cam. Is there anyway to prove or disprove this? have the engine tore apart and want o make sure the new gaskets will be enough.
 

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Measure the bore - .040 over will be 86.00 mm or 3.39 inches
Original bore was 85.00 mm or 3.35 inches
Stock head gasket will work until it goes to 87 mm (416cc) - 88 (426cc) and 89 (435cc) use the same head gasket as the 87 mm bore (Cometic part number H402027S)

As to the cam - depends on the manufacturer - Hot Cams are usually stamped 07 = stage 1, 8 = stage 2 and 51 = stage 3 - others have to be measured for lift and duration to determine the 'Stage'
 

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Discussion Starter #3
Thanks! Where’s the best place to by the Cometic gasket you noted?
 

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Just search Ebay or Amazon for 89 mm TRX400EX head gasket - you can find them from Niche and other vendors - Cometic is there also as a top end set. If you just want the head gasket, I keep a few on hand. I also have one complete top end set on hand.
 
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