leaking head gasket on cl77

305nutt · Post by **305nutt** » Sun May 08, 2011 6:17 pm

Has anyone had a headgasket leak oil on a cl77 or cb77. I just finished an engine last week and when I ride the bike, and shut it off, it leaves 2 drops of oil on my floor. The headgasket is leaking directly under the spark plug on both sides of the engine. I pulled the plugs and tightened the 6mm nut and retightened the head nuts, and that seemed to help, but it still leaks. I had the head surfaced and the top of the cylinder surfaced to make everything nice and flat. I also used a genuine honda headgasket, and o rings, even put a fine film of black silicon on both sides of the gasket. My question is, 1 has anyone run into this and 2 could have surfacing them caused the long studs to be too long and my top nuts not tightening down all the way? Any help would be appreciated. This is the 6th 305 I've built and never had this problem.

Hotshoe · Post by **Hotshoe** » Mon May 09, 2011 11:19 am

The only time this ever happen to me that I can remember I had forgotten to tighten the 6mm nuts by the plugs and as soon as I did the leak went away.
I doubt stud length is an issue if you were able to get proper torque on the cap nuts.
Assuming the resurfacing of the mating surfaces was done properly, I'm suspicious of the silicon on the head gasket.
I'd loosen and retorque everything and maybe give them a couple of extra foot/pounds, being careful not to break anything of course.
Hopefully someone else will come up with a solution that doesn't involve a forensic top end job... good luck.

rrietman · Post by **rrietman** » Mon May 09, 2011 11:35 am

are you sure you aren't just getting some weeping from right around the spark plugs? pretty common and can look a lot like a head gasket leak. do a leakdown test and blow smoke all around the head with the pressue on.
Thanks
Randy

Goodysnap · Post by **Goodysnap** » Mon May 09, 2011 5:08 pm

Being that you've surfaced both the head and the cylinder- Check that the studs are not bottoming out in the nuts. I had some leakage issues, but a retorque after a few run cycles dried it up.

e3steve · Post by **e3steve** » Mon May 09, 2011 6:59 pm

Another viewpoint: could be that the steel 'skulls' have parted company with the head(?).

305nutt · Post by **305nutt** » Tue May 10, 2011 5:48 am

Thanks for all the suggestions. I took all the head caps loose yesterday and looked like maybe a couple of the studs were a little longer than the rest so I double stacked copper washers on them, retorqued everything and rode it, so far the right side looked like it was a little damp, but no real leak, so I'll probably go over and retighten today 1 more time and see what that does. Nutt