Topic: 73 Honda cb450

[bigragu]

Just picked up a cb450 it runs but the left side pipe does smoke? Could it need a valve adjustment? Not real familiar with this bike 1st one.

[Markcb750]

Gray smoke...oil.  Try some Seafoam (or similar) over night in the cylinder bores.   Do not reinstall the spark plugs till you clean out the Seafoam by kicking it over a few times.

Black smoke..running rich, clean the Carbs, reset the floats and sync them.

Usually not valve adjustment.   Although not a bad idea to check when bringing the bike into good working order.

[bigragu]

Thanks for the info, it's white/gray smoke so maybe I'll give the Seafoam a shot and change the oil?
The oil did smell like gas not sure if that"s related or a separate issue?

[Markcb750]

Always best to get unknown oil out and new oil in.  I would let the Seafoam work on the piston rings before you change the oil. 

When  I did this Seafoam flush on my 750 over 10,000 miles ago  I put a few milliliters in each  cylinder every few days for about a week.   



The 450 motor is pretty durable, My '67 sat outside from 1982 to 2011.  Motor still kicked over! I have it tore down now as part of a restore.

[JohnG]

I'll toss in one cautionary note.  If you change the oil  and then go to start the bike, crank it over a bit  (maybe with the plugs out and a second battery)  so as to get oil to the top end before running.

The oil delivery system is a bit more primitive than the 750  (see shop manual for details)  and it can take a little bit of time for oil to get up there.  There is a centrifugal filter you can clean on the left side.  Also a strainer on the pump.

A real drawback is lack of an oil pressure light!  More reason to be conservative. You don't want to fry one of the cams and it's followers.

[bigragu]

worked on it today and tried the Seafoam with little results? There's a very slight trace of smoke coming out of the left spark plug area? Thinking I need to replace the head gasket?