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Blown head gasket


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Hey guys, hopefully someone can help me here. I have an 06 banshee which is pretty much stock except for pipes, jetted carbs and air filter. The problem i am having is back a year ago i blew a head gasket, i pulled down the motor and did a top end rebuild. After the first couple of rides the overflow kept spitting out coolant and the bike was back firing, so i pulled the head back off to check and found the head gasket leaking into the cylinders again. So i removed the cylinders and sent them with the head to the machine shop to have them both faced just in case of slight warpage. I also fitted a genuine head gasket instead of the wiseco one that came with the rebuild kit. The head was torqued down correctly and re-torqued after a couple of heat cycles, I even used hylomar on the gasket to try help it seal up. A few more rides later and same problem, pulled the head off yesterday and found both cylinders leaking in at the intake side of the combustion chamber. Im stumped at whats wrong and not sure what to do next other than purchase new cylinders and head and start again :confused: . Any help would be much appreciated, thanks in advance. :cheers:

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were the heat cycles up to complete operating temp, almost over-heating? 2 hot cycles, and complete cool-downs, like 2-3 hours cooling off, and a few nuts should be just about finger tight.....some have used that copper spray, but i never have....

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Hey AKheathen, I believe the heat cycles were complete. As both times i checked the torque settings i couldnt tighten the head nuts anymore and when removing the head after 4 or 5 rides ( usually a week min between rides) the head nuts were still tight.

 

Check the head for cracks. I had a leak, and it took a while to find the almost invisible crack that was causing it.

What caused the gasket to blow the first time?

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That was my next thought, getting the head sent off to be crack tested. The only thing that steers me away from that being the problem is that that gasket leak is in the exact same spot on both cylinders which i thought would be pretty unlikely but stranger things have happened i guess. The gasket blew originally from me being stupid and smoking up some old tyres for too long ( i know, wat an idiot banghead )

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youre head is definitly done, it probobly cracked from being held wide open not moving, doing a burn out. if youre head and cylinders were resurfaced and it still leaked, there is an almost invisible crack there.

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That was my next thought, getting the head sent off to be crack tested. The only thing that steers me away from that being the problem is that that gasket leak is in the exact same spot on both cylinders which i thought would be pretty unlikely but stranger things have happened i guess. The gasket blew originally from me being stupid and smoking up some old tyres for too long ( i know, wat an idiot banghead )

well, if you are gonna spend the money to crack check, you might as well buy another one...they are a dime-a-dozen

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After the cylinders are installed on the cases, lay a straight edge across both of them at the same time and make sure the deck heights are equal. If your cylinders are 2 different heights the head will never seal. Also, a stoch head that has been cut too much will never hold a gasket, the metal is to thin to be solid enough to haold the gasket.

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