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Discussion Starter · #1 ·
This 74' CB 450 K7 I just recently purchased doesn't seem to run to bad but after a short ride a couple of days ago ( 1st ride since purchased ), I returned from the ride and there was oil dripping from underneath the bike making a mess of the frame/swing arm and rear wheel ?

First I thought that maybe it was residual chain oil since I heavily coated the chain since it was dry. But I don't that was the case since there a lot more "light" oil sprayed on the bike than from just oiling the chain ?

Wiped everything down and inspected bike underneath and couldn't tell where the oil was coming from. Even put the bike on the center stand and ran it thru the gears but didn't observe any oil dripping ?

So, then I thought maybe the crankcase ventilation system was obstructed ? Looking at the rear cover and the ventilation tube running from it downward by the rear frame tube, it appears to be looping back up under the countershaft sprocket cover ?

I checked the engine oil before and it was overfilled. Let the engine set overnight and definitely above the upper level mark on the dipstick. Now do you check the engine oil with the dipstick screwed in all the way or the dipstick just sitting on top of the threads ? Either way it's Too Full !

Pulled the air cleaner covers off and the air cleaner are not wet with oil. The engine oil does not smell like gas either.

How doe the crankcase ventilation system work and is the tube routed correctly ?

Describing what I observed, do you think this might be the problem ?
 

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Center stand or level, dip stick not seated but not screwed in. Over fill it and the pressure will vent the oil plus I think it puts more stress on the engine. Perhaps loosen the drain, let some out so its more between the upper and lower marks and not over it.
 

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Discussion Starter · #3 ·
That's a start and will drain a little oil out, but do you know how the vent tube is routed or can it be eliminated all together ?
 

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The vent tube on mine routes straight from the valve cover to the gap between the transmission and frame, where it just hangs straight down. If you remove it, you will get oil vapor on everything.
 
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