Cb77 oil leak

fab60 · Post by **fab60** » Sun Jun 15, 2014 7:18 pm

Hi guys so I've only had the bike for a little while and have noticed some oil leaking/wetness in some areas. I know these motors are suppose to be leak proof but how realistic is it from a 40 yr old bike?? Haha. Anyways I'm getting some oil right under the spark plugs where there is 10mm nut, one on each side. Also noticing a little wetness on one of the valve tappet covers on the right side toward the rear. Do these screws need to just be re torqued or is there a bigger problem lying beneath all this? I recently checked the compression and it was 170/165

Cheers

Rick

Goodysnap · Post by **Goodysnap** » Sun Jun 15, 2014 9:07 pm

As for the tapet cover easy enough to replace the seals. They are probably hard and brittle, as may be the rest of the rubber seals. Typical for some seepage from the spark plug area where the steel and aluminum meet in the head. Not much to do here other than replace the head.Mine seeps a tad even after resealing.

Goodysnap · Post by **Goodysnap** » Sun Jun 15, 2014 9:08 pm

As for the tapet cover easy enough to replace the seals. They are probably hard and brittle, as may be the rest of the rubber seals. Typical for some seepage from the spark plug area where the steel and aluminum meet in the head. Not much to do here other than replace the head.Mine seeps a tad even after resealing.

fab60 · Post by **fab60** » Sun Jun 15, 2014 9:22 pm

Thanks Goodsnap for the advice. Now for the 10mm nut under the spark plug will tightening this up help with the oil seepage? Bike is running pretty strong and well.

Cheers

Rick

Goodysnap · Post by **Goodysnap** » Sun Jun 15, 2014 9:37 pm

If you find them loose it may slow the leak. Most likely coming through the head itself.

sarals · Post by **sarals** » Sat Jun 21, 2014 1:48 pm

Early on I found a tiny amount of oil around both spark plugs after my engine had been running a while, under load, and had gotten good and hot. It seemed to come from the gaskets behind the tach drive on the left side and ignition drive on the right side. You might give those Phillips screws holding those drives a whack with an impact driver, and see if that helps. It did on mine. I still DO get a little bit of oil around the right side plug, and I'm not quite sure where that is coming from. I'm hoping that gasket behind the ignition drive might still be seeping a little. Those 10mm nuts/studs at the plugs have no oil passages anywhere near them, so it's likely that the oil you see on your engine is just collecting there.

fab60 · Post by **fab60** » Sat Jun 21, 2014 4:52 pm

Hey thanks for the insight, I'm going to give that a try tonite. My leak sounds similar to yours in that it happens when the bike gets good and hot.

Cheers

Rick