Topic: what goes under the battery box?

[dgilling]

So it looks like something is missing under my battery box.  Is there something that is suppose to be under there?  anybody have any pictures if there is something supposed to be in there?

[754]

on what?

if it is a 72 or earlier 750 CB the answer is swingarm..

do I win?

[dgilling]

no win for you its a 77 cb750.  Sorry i forgot to say that

[ekim98]

Don't know the actual name, but it's the canister for the exhaust emissions hoses I believe. At least thats what my 78 750 had under there.

[dgilling]

what does it actually do?  something for emissions?

[ekim98]

Yea, I think it's for emissions and condensation trap,something like that. It pumps exhaust gas etc. back thru the carbs and "reburns" it.Mine's gone now. It wasn't hooked up when I got the bike and I didn't feel like chaseing down hoses and stuff. I'm not a big green earth person. If your in Calif. you will probably need it on there??

[TwoTired]

It's a crankcase breather filter and water separator.  It's function is to take the piston ring blow by, hot oil vapors, and water condensate from the engine crankcase and feed them to the carburetor inlet for subsequent burning by the engine cylinders.  Earlier models simply dumped these carcinogens into the atmosphere to settle into the lungs of mammals.   It has nothing to do with exhaust gas recirculation found on many autos.

There is no inspection in Cal to require it still function on these old bikes.  Though some believe there should be.  Then again there are some who believe all vehicles over 10 years old should be scrapped.  But, I digress...

The small vacuum that the stock breather set up applies to the crankcase, actually speeds the removal of condensate from the crankcase, extending the useful life of the oil, and the engine.  Don't know how to quantify it though, as there are so many other variables to engine longevity.

Cheers,

[eurban]

It's a crankcase breather filter and water separator.  It's function is to take the piston ring blow by, hot oil vapors, and water condensate from the engine crankcase and feed them to the carburetor inlet for subsequent burning by the engine cylinders.  Earlier models simply dumped these carcinogens into the atmosphere to settle into the lungs of mammals.   It has nothing to do with exhaust gas recirculation found on many autos.

There is no inspection in Cal to require it still function on these old bikes.  Though some believe there should be.  Then again there are some who believe all vehicles over 10 years old should be scrapped.  But, I digress...

The small vacuum that the stock breather set up applies to the crankcase, actually speeds the removal of condensate from the crankcase, extending the useful life of the oil, and the engine.  Don't know how to quantify it though, as there are so many other variables to engine longevity.

Cheers,

Just to add here, this object acts as a separator that allows the engine to rebreathe the vapors without sucking any liquids in.  The liquids collect in the tube running from the bottom of the separator.  On a stock bike this tube runs through a fitting on the right side exhaust bracket and terminates in a plug.  Part of routine maintenance is to drain the nasty gook from this tube.

[professorzed]

Would this be the same in a 1982 Honda 650?
I bought a 'basketcase' motorcycle with the front end & engine of a Honda, and the rear end of a Harley. The battery box is HUGE, enough for three motorcycle batteries. I discussed this with a scrapyard & he showed me how a battery fits on a Honda Nighthawk 650, sideways with everything nice & tight beneath it.

[TwoTired]

Would this be the same in a 1982 Honda 650?

I've not seen it, but the bike almost certainly was equipped and configured for a recirculating breather from the factory.

Cheers,