1977 Honda CB750F update 3

Well, after installing and playing around with the rebuilt carbs for a  couple of weeks, it became clear that something else was wrong so I checked the valve timing and it may well be off, but its hard to tell since the timing marks are on the ignition advance unit and it has so much slop (maybe 5 deg). Apparently manufacturing tolerances weren’t all that good back in the 70’s!

The #1 cyl also seemed cold and wet, plus the bike would smoke a decent amount on start-up and throttle blips. The motor had to come out anyways so I can paint the frame and a whole engine gasket kit is only ~50.00… so I decided to tear it down and do some investigating. Rings and cylinders look perfect (the bike only has 12K miles on it) cyl 1 had oil in it and as you can see from the pictures, the head and valves are quite oily. Also, 1 and 4 valves and seats have pitting on them- probably because they were the valves that happened to be open when the bike got stored many years ago and they rusted a bit. So, I will lap the valves and install new valve stem seals, hone the cylinders and reassemble. That will at least fix the oil burning problem. Here are a few pictures from the tear down- Always keep your valves and parts labeled and marked so it gets put back together correctly!

WP_20140915_001 WP_20140924_003 WP_20140924_004 WP_20140925_008 WP_20140926_001 WP_20140926_002 WP_20140926_004

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!

You must be logged in to post a comment.