2004 Yamaha raptor 660 leaking coolant from head gasket below front exhaust pipe afte - Yamaha ATV Forum
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post #1 of 4 Old 08-12-2019, 09:50 AM Thread Starter
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2004 Yamaha raptor 660 leaking coolant from head gasket below front exhaust pipe afte

I did a full rebuild, ran fine , no leaks , after I broke it in and I changed the oil so I could really ride it I notice it was leaking coolant from the head gasket on the front of the motor below the exhaust pipe. I rebuilt it with a 102 piston and jug kit, using a cosmic gasket kit. Should I just retorque the head bolts ? Or should I change the gasket out again, and if so can I use a stock bore ome gasket and not a 102 bore gasket b/c I don't have another 102mm gasket.??? Also if I was to take the head back off could I re use the head gasket that's on it now since it don't have any hours on it other than break in stage, it's a cosmic gasket?
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post #2 of 4 Old 08-12-2019, 10:50 AM
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you cant reuse or re torque a head gasket you have one shot at it. you will need the correct 102 gasket. i would check the head a jug for flat before i put it back together. unless you did not follow the correct torque procedure that gasket blew for some reason
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post #3 of 4 Old 08-13-2019, 06:54 PM
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I don't agree, head gaskets can be reused several times depending on what kind of gasket it is. It used to be common practice to retorque once the engine cooled down from initial run. If it is steel shim for instance it can be reused but if it had printed on seals that have been damaged it is harder to do. The real key here is to always check head and cylinder to be sure they are flat. Even a new cylinder should be checked, you just don't know the quality. A removed head will almost certainly have some warpage to it and should be carefully checked. In this case I would mark the position of each nut or bolt, remove pressure from the coolant system and retorque the head bolts. If they do not tighten any, remove some torque from them and retorque. Check the marks you made to get an idea of what you have accomplished. Worst case you will need to remove head and carefully examine the gasket to see why it failed.
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post #4 of 4 Old 11-05-2019, 10:11 AM
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These are coated steel head gaskets that crush, it is very obvious when you compare a used one to a new one that they crush when they are torqued. There is also a sealant coating that adheres to the mating surfaces and visibly comes off the gasket .
I have been through 5 head gaskets on my 11:1 102mm 660 in about a 5 year troubleshooting adventure. I would visit the dunes once a year and the head would lift and blow while the engine was hot and 2 of the 3 times at Little Sahara I was at the drag strip. I replaced bolts, lock tighted them, upped my octane, decked both surfaces and tried 2 different gasket brands before getting it to seal. The gasket would hold for all the slower trail riding around home.

You MIGHT be able to copper coat it and get by, I did once in a pinch, it blew later, but it may not be worth the hassle later.

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