Topic: Air cleaner

[cb750k7]

Hi all,

As it turned out,  I have a 78' frame with a 76' engine.

When looking thoroughly at the bike,  I found a part that was hidden under the battery but was not connected to any other part.
(See attached file,)

When looking at the 78 manual,  it is described as an Air Cleanr.

Where was it originally connected?  What does it clean?  Is it missing in the 76’ engine or belongs only to the 78’ engine ?


Thank you all.

Jona

 

[754]

does it have a hose barb, perhaps engine breather hose went to it?

 You may want to machine down your sprocket carrier or swap to earlier one.. unless you changed sprocket shaft in your engine or used a 76 rear wheel, your chain is running 1/4inch out of line..

[medic09]

Shalom Yona!

That looks to me like part of the pollution/emissions control (EPA) set-up.  I think those only came into use in '77.  An earlier engine wouldn't use it.  So if you have a '76 engine, it is probably just dead weight.

Anyone else!

How's the riding in Azor HaCarmel?  I think you probably have the only 750Four in the country!

[TwoTired]

That air cleaner is a crankcase vent recirculator.  It takes hydrocarbon carcinogens (vented towards the lungs of other mammals on previous models) from the crankcase and allows them to go into the engine intake to be burned before going out the exhaust.

This is yet another reason to avoid those evil pod filters that bypass this device.

Cheers,

[cb750k7]

 You may want to machine down your sprocket carrier or swap to earlier one.. unless you changed sprocket shaft in your engine or used a 76 rear wheel, your chain is running 1/4inch out of line..

How do I check it?

I do have a 17" rear wheel.
Tried to open the screws on the front sprocket,  but had one stubborn screw.  Till I will have a JIS screwdriver,  I won't force it with a regular Philips screwdriver.

That air cleaner is a crankcase vent recirculator.  It takes hydrocarbon carcinogens (vented towards the lungs of other mammals on previous models) from the crankcase and allows them to go into the engine intake to be burned before going out the exhaust.

This is yet another reason to avoid those evil pod filters that bypass this device.

Cheers,

Can it be used in a 76' engine?


TNX

Jona

[medic09]

TT, wasn't that EPA recirculator only for the 77-78 engines?

[754]

It can be run out of line, just wears a bit more . Quick check.. look at back sprocket probably shiny sides on the outside, but not the inside (because it is not touching/rubbing)

[TwoTired]

That air cleaner is a crankcase vent recirculator.  It takes hydrocarbon carcinogens (vented towards the lungs of other mammals on previous models) from the crankcase and allows them to go into the engine intake to be burned before going out the exhaust.

This is yet another reason to avoid those evil pod filters that bypass this device.

Cheers,

Can it be used in a 76' engine?

The 77-78 CB750  air box has a fitting on top center that accepts a hose from your extra filter.  I don't know if earlier 750s have this.  I don't know if your bike still has the 77-78 airbox or if an earlier airbox was fitted along with the older engine.

TT, wasn't that EPA recirculator only for the 77-78 engines?

Outside the US?  I don't know.
For US models, the CB750F had them since 75.  The K models incorporated their use in 77.

All the CB550s had a similar device beginning in 74.  I recall that the 75 CB400F I had for a short time had one as well.

Note that the recirculator itself does not in any way change the state of engine tune.  Their is no risk adding that device to earlier engines, and allows everyone to breathe with slightly less risk of harm.

Cheers,

[cb750k7]

Shalom Yona!

How's the riding in Azor HaCarmel?  I think you probably have the only 750Four in the country!

Hi Mordechai,

It started to rain today,  yet not so cold.
Not sure about more CB750 left in running condition,  but there is a new wave of importing "ASFANUT" so maybe there are more.  Haven't seen CB's yet,  but there are a lot of 75-77 Goldies.


Bye,

Jona