Topic: Oil leak and smoking from left hand header at engine -CB750K4

[andy750]

Last year I replaced the valve oil seals, piston rings and head gasket on my CB750K4. Reassembled everything and installed and the engine still leaks oil....I did the talcum powder test and I can see oil around the extreme left header insert at the engine (by torchlight last night)....when I ride the bike and sit at traffic lights I can see smoke (whispy) coming from the same area....probably the oil as it leaks out.....head gasket looks ok from what I can see. My question is could it be the copper gasket exhaust seal needs replacing or could it be leaking oil at the studs? Does oil even get behind there?? Any help/suggestions appreciated.

Thanks
Andy in Boston

[bryanj]

should be no oil there unless a valve guide is gone, could be coming from one of the rubber pucks under the cam towers

[Kevin D]

Andy, the first time I had the head off my K1 (1973?) I replaced the original head gasket with a new aftermaket head gasket. The head was carefully reassembled and properly torqued but when I started the engine, oil POURED out the head gasket. It would have pumped itself dry within 30 minutes. I was crushed. I pulled the engine back out and ended up using the original Honda head gasket with no further serious problems, I still have a little seepage. If I ever take the engine out again I will be torquing the head bolts to the high end of the range or maybe a little beyond. Do a search of the archives.

[Killer Canary]

I had a '79 750F that I replaced the head and base gaskets on, it started weeping oil on the first ride. I re-torqued the head bolts to top of tolerance plus 5% and that stopped it. Might be worth a try.