CB350 white smoke from left carb/engine. What's leaking?

[motobutch]

I've had my first bike for a few months now (72 CB350) and it came with foam pod filters from the last owner. A couple weeks ago I changed the foam back into the oem air filters and messed with the air mixture screws to get it to idle (started with the spec 3/4 to 1 turn but had to up it a bit to 1 1/2 to 2 for idling). Since then, I've run into a few issues.


When I started the bike from cold it idled fine and ran okay for about half an hour. Then at stops I noticed a strong burning rubber smell that also smelled like gasoline. I put the bike in neutral and let it idle and I noticed a bit of white smoke coming from the left side airbox/carb region. When I revved it to about 3000 rpm, the smoke got stronger and some was coming from the top end of the engine as well.


I've also noticed that when I come to a stop at the end of a ride, a small puddle appears. When I intentionally try and make the bike leak by revving it, rocking it back and forth, or just letting it idle for a long time, I can't see any drip or stream of liquid, so I'm having trouble telling exactly where the leak is coming from. There is definitely discoloration on the bottom left of the engine though. I've attached a couple pictures with my best guesses. Is it leaking oil, gas, both?!


I don't think all of these issues are a direct result from changing the air filters, but that's when I started noticing the problems. I'm pretty new to vintage bikes so I'd appreciate any advice, not trying to damage the bike or blow up while riding!

 

[66Sprint]

Do NOT restart engine until you verify there is NO fuel in the oil...... (check level, and smell the dipstick)......

Mixture screws should be set at highest idle WITHIN the specified range.....Two turns out is excessive on the 350's.....

 

[LongDistanceRider]

For the oil leak I would get some spray on engine cleaner like Gunk so the engine is clean. Washes off with regular garden hose. Once it dry throw a couple handfuls of baby powder in the suspect areas and run the engine for a few minutes. The powder turns in to a gooey mess where the leak is. NOTE: these are air cooled engine so running more than 5 minutes w/o air flow over the engine is bad for them.
Normal mixture screw setting is 3/4 turns out +/- 1/4 turn. Opening to 2 turns would indicate a vacuum leak or possibly a restricted carb passage.

 

[teebo]

For the oil leak I would get some spray on engine cleaner like Gunk so the engine is clean. Washes off with regular garden hose. Once it dry throw a couple handfuls of baby powder in the suspect areas and run the engine for a few minutes. The powder turns in to a gooey mess where the leak is. NOTE: these are air cooled engine so running more than 5 minutes w/o air flow over the engine is bad for them.
Normal mixture screw setting is 3/4 turns out +/- 1/4 turn. Opening to 2 turns would indicate a vacuum leak or possibly a restricted carb passage.

I was going to say something similar. Except the baby powder part. What a great trick.

I got every last bit of gunk off including with a wire brush and solvent. Oil travels in unexpected ways. I also keep the floor under the bike clean. Makes it easier to see new leaks and when my bike piddles on the floor.

I've had to replace 3 gaskets (both crankcase covers and tach seal). It appears my seal around the kick starter has a very slow drip onto the muffler. Nothing pressing. Just annoying.