CB650 Oil Leak

I got the 1980 CB650 out one time earlier this year. It was, as always, a struggle to get it started after it sat for about two months, and I vowed to keep starting it every few days to avoid the battle in the future. I had replaced the front tire with a Bridgestone Spitfire S11F 100/90H-19 in place of the discontinued Bridgestone Battlax BT45 I’ve been running. I hope the BT46 model is as good, since I still intend to run it on the rear. I did pinch the new tube (gah) and rather than patch it I bought a heavy duty Kenda tube instead.

So as I say, I took the CB650 for a nice 20+ mile ride, one of my local ridge loops, and was pretty happy.  Until the next day when I saw an oil spot under the bike.  I wasn’t 100% sure the oil was from that bike, so I got a flattened-out cardboard box and parked the bike on it to be sure.

Yup.  Oil leak.

Lying down on the box, I could see that the bike seemed to be leaking around the edge of the sump.  Another bad gasket, I assumed, and I started making plans to get a new one and get it installed.

Then I remembered how I quelled the top-end oil leak of my XS650 by retorquing the head.  I decided to try retorquing the sump bolts, but to do that I needed to know the torque specs.  Honda, it seems, did not publish torque specs for the sump bolts.  Gah, again.

The slightly larger bolts securing the sump plate to the XS650 had a 7 ft-lb spec, I noticed; so I set my torque wrench for 5 ft-lbs and retorqued the Honda’s sump bolts, starting with the one in the middle of the left side and working out, in alternation, first one more in front, then one more in back, and so on until I had readjusted the entire left side to that torque.  I decided, based on where I saw oil on the sump, to stop there rather than going on around, and maybe later I’ll regret that.  Who knows?

What I do know is, I took the bike out for another similar loop and parked it over a fresh clean white paper towel.  So far, after about four days, no signs of further leakage.  Keeping my fingers crossed…