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Drain plug gasket/screw for CB450K7

200 Views 4 Replies 4 Participants Last post by  Montanabill
Hello all,
I just recently (6 months ago) restored a 1974 CB450K7.
Everything is working fine except I have a small leak from the left carburetor.
I had to replace the aftermarket petcock because that was not shutting off with a Honda petcock. Now when I turn the petcock to stop no fuel from the tank go to either carburetor.
Anyway if I keep the petcock to on and shut down the bike there is a slow (3 drip) leak from the drain line. I have taken the bottom fuel bowl on the LHS carburetor and cleaned out the fuel supply line with brake cleaner. My next guess as to the leak is the drain plug as it drips out of the drain line. Can anyone tell me what size seal/gasket is on the drain screw (is it 6 mm).

Any other suggestions would be greatly appreciated.
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How does overflow tube seem? Could it be leaking at the base of tube in the bottom of the bowl? Leaks while running?
Definetly not coming out from float bowl gasket or side of carb?

id check your float valveso you know it wont go into the engine to be safe.

maybe wrong kind of drain plug? There are slightlydifferent styles for different carb models.
Anyway itd be better to always turn the petcock off when not running, as gas can overflow into the crankcase
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Stand pipe in the bowl could be cracked. I've soldered a few

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I just fixed a 350 with a cracked overflow pipe in the float bowl. For yours I would pull the float bowl off and set it up on the bench and fill it with gas to check for leaks. If it holds then you probably need to pull you foat needle and seat and check them. Also check your float and float level. sometimes I have to play with the foalt level to get the bike to not leak, especially when parked on the sidestand.
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