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Discussion Starter · #1 ·
After a long absence from working on my 1964/1965 CA95, I finally got the last bits on. It runs better than I expected but smoke is pouring out of both exhausts. I had the engine rebored and put in new pistons, ring, new valves etc. It seems to be smoking more now than before the rebuild. I am beginning to think these bikes can’t actually run without smoking like a chimney.

I checked the compression with two different gauges with the engine warm, throttle open and the choke not engaged. I got 150 on the right and 145 on the left repeatedly. I don’t think I had the left cylinder tightened enough. My adapter is too short. I am at sea level.

The smoke was not black. It was white or gray and does not start until the engine has warmed up. I know I should know the difference between gray and white smoke but I don’t. All I can say it persisted for about 3 houses in either direction.

I have only ridden it for about 45 minutes total. I had to stop as birds were dropping out of the sky. That should be enough time to set the rings especially with the compression readings I have, right?

I thought maybe it was just residual oil in the exhaust but after three rides, it has not gotten any less.

The oil level is correct and the crankcase vent is not plugged.

I checked the plugs and have attached pictures. They were black and dry with just a small amount of carbon.

There is no smell of gasoline in the oil

Before I tear the engine apart again (groan!!), is there anything I missed?

If it is running rich, shouldn’t the smoke be dark?

If I tear the engine down, what should I look for?

The mechanic said the valve guides looked good. If they were not, could they leak enough oil to cause this kind of smog bank?

Could I have gotten one of those fussy oil control O rings (that nobody seems to know where they go exactly) out of place? Could that cause this much smoke?

I checked the ring gap and staggered the rings before installing them.

I know that an upside down oil scraper ring can cause this. But all you have to do is put the manufactures symbol to the top and they should work, correct? After all it looks like I got the other 4 rings in OK.

I admit I put a little assembly lube on the pistons when I installed them. There seemed to no common consensus on whether this was a good idea or not but it made sense to me. I turned over the engine with the starter and no plugs before I started it the first time.

Any thoughts would be appreciated.


· Registered
344 Posts
Very smokey, I would get the bike out of town and ride it a while. It should be better that it is
after the overhaul. Are you sure the pistons match the bore, got the correct oversize???
I rode a CB77,305 engine. I seized the cylinders and then did a bore and ring job
and it worked well. Keep us posted when you find the problem.
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