Topic: Question about Loose Tubes on CB750...Newbie here

[edosm]

Hello,

Sorry about the basic questions...newbie here

Just got a "Rough" 1975 CB750...and I'd like to clean up the engine compartment a bit...and wiring
I need to know if particular HOSES should be connected to something or hung loose for drainage.

1) I have 4 little hoses coming off of Bottom of Carb nipples...What do I do with those.
2) I know fuel tank has a loose Hose...is that for overflow right
3) What is the DEVICE connected at bottom of Oil Bag...is it for oil drainage and such...what's the correct hose path of those tubes (It has several valves openings)

Wiring Question: Ignition assembly.. There appears to be 4 wires coming out of side of case...at some point do 2 of these wires connect together and connect to 1 wire on bike...Yellow wire in particular... I'm trying to read a wire diagram...but gosh..a little tricky...any one have a Hand written Scetch of wiring that simple to read.

Thanks so much
Mike

[Bob Wessner]

1) I have 4 little hoses coming off of Bottom of Carb nipples...What do I do with those.

These are drain hoses in case the float bowls overfill (e.g. float valve sticks open, etc.) The are usually bundled together and drape over the rear of the transmission. If you always shut off the petcock when you stop, these shouldn't come into play.

Can't help on the others, not familiar with the '75.

[Einyodeler]

Here are a colored wiring diagram and a "simplified" one.

[scondon]

1) I have 4 little hoses coming off of Bottom of Carb nipples...What do I do with those.

   As Bob said, these bundle together and drape over the rear of the engine. There is a bracket machined into the rear case of the engine that these tubes insert into to hold them in place.

2) I know fuel tank has a loose Hose...is that for overflow right

   Correct, it is for overflow. It routes back and connects with a longer tube at the rear of the tank, just in front of the battery box. Often this second, longer tube has gone missing over the years but yours may still be there.

3) What is the DEVICE connected at bottom of Oil Bag...is it for oil drainage and such...what's the correct hose path of those tubes (It has several valves openings)

    I assume you're talking about the Pollution Control device mounted to the bottom of the battery box and behind the oil tank. Most people leave this disconnected. If you wish to "spare the air" and reconnect it I believe the routing is... Cam breather to top nipple,connect rubber line from middle nipple to top of airbox, bottom nipple is for drain tube. Foam catch filter inside PC device.

     Not clear which wires your talking about and where they are on the bike.

[edosm]

Thanks so Much...I love that cartoon looking diagram..LOL.A big help.

Also Thanks for the info on pollution control device...Is it safe to say that If I leave it unpluged the Bike will still idle fine...or is it a must to keep it connected.

As far as the wires I'm trying to identify  ..They are the ones that come from the Right side of Bike Incased in Ignition cover I believe..( the wires are near back of case)The cover is where the Rear Brake Pedal is..4 wires total ..1 yellow 1 blue...do these at some point connect to each other  OR do they always go separate on there own little path to the bike harness.. Sorry that I can't be more discriptive.
Thanks

[OldSchool_IsCool]

Ed,

This interactive wiring diagram should be of help.

http://oldmanhonda.com/MC/wiring750K1.html

It sounds like you are describing the wires that lead to the points.  Turn off all systems except COIL in the interactive diagram and you should see how they are supposed to work.

[750goes]

The blue and yellow wires are independent wires coming from your points and going to the coils, they connect near the bottom of the oil tank from a bunch of wires from the main harness which includes the two wires for the rear brake switch.

Just connect yellow to yellow and blue to blue,and if you have a standard rear brake switch the other two wires should match as well.

Hint - do a continuity test for your yellow and then blue wires from the coils down to the points - it will tell if you have a good path for the electrics...