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Hello all,
I trustingly bought a 73 cb350 from a guy who said that all it needed was the ignition coils replaced... learned my lesson..
Did that... couldn’t get it going.. cleaned the carbs and air filters... adjusted the points.. finally was able to pop start it and it ran for about 3 minutes, during which smoke and oil came out of the top end breather tube..
Checked the plugs and the left one was clean- hadn’t fired once.

I’m wondering what the implications of the oil and smoke could be and if the cylinder not firing could be connected.
I haven’t checked for compression..

I’d rank myself a novice... but am fairly mechanicly minded..
Any ideas and advice would be greatly appreciated.

Thanks
 

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Might be a holed piston or a valve issue, you need to check the compression. If you don't have a gauge handy try kicking it over with one plug removed, then the other. If it kicks noticeably easier on one side then you'll know.
 

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plug not ignited, should trace back all from points, condenser, to coil.

and oil coming out the breather, like anwer above, need to check the cylinder/rings, usually the compression goes below (thru leaking part), pushing the crankcase with air that blows oil upward to the breather...
 

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W_H,
Go back to the basics: Fuel (in the right quantity), Spark (at the right time) and compression. Is the clean plug wet with fuel? You should be able to smell it on the plug. If not, gas is not getting through the carb. If the plug is wet, plug it into the cap and hold it on the head while turning it over. You should see a bright spark. If it is wet, it could be gas fouled. Try swapping plugs from side to side.
A compression check is a good idea. Don't put too much stock in it, it is easy to get bad readings. When an engine runs there is combustion gasses that leak past the rings. This is the reason for the breather tube. Modern engines recover these gasses and route it into the intake to be burnt. If the bike has been sitting for a while it could just need to be run to loosen it up.
Don't despair, I was stuck for weeks before I discovered I timed the intake cam wrong on my newly rebuilt '72 CB450 DOHC. Now it runs like a new bike. Regardless of the problems with your bike, it can be fixed and you can do it with the help from this forum.
Do us a favor and post some pictures. We love pictures.
 
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