Honda-SOHC

SOHC.co.uk Forums => CB750 => Topic started by: Graeme77 on March 17, 2015, 08:07:48 PM

Title: earth cable
Post by: Graeme77 on March 17, 2015, 08:07:48 PM
Starting to put my bike back together and cant remember where the earth cable went. I know it goes on the top rear engine bolt, but outside frame or between frame and engine?
Also, has anyone got any pics of a tidy standard electrics/battery area?

Mine is an f1 if it makes a difference.
Title: Re: earth cable
Post by: mike the bike on March 17, 2015, 10:08:44 PM
Inside the frame
Title: Re: earth cable
Post by: martin_uk on March 17, 2015, 10:09:03 PM
I believe it is between engine and mounting bracket
Title: Re: earth cable
Post by: dieffe on March 17, 2015, 10:11:32 PM
The earth goes between the frame and the engine as you said on the top left hand side.
Title: Re: earth cable
Post by: Graeme77 on March 17, 2015, 10:24:50 PM
Thanks. I thought it probably would do but I found pics on the internet both ways.
Title: Re: earth cable
Post by: Bryanj on March 18, 2015, 07:58:30 AM
Either way you need to make sure there is no paint/powdercoat where the bracket touches the lead/engine
Title: Re: earth cable
Post by: martin_uk on March 18, 2015, 08:56:02 AM
I believe it is between engine and mounting bracket

Mine is on right side, guess it depends on length of cable
Title: Re: earth cable
Post by: Graeme77 on March 18, 2015, 07:44:29 PM
I seem to have another earth cable left over. Its about 5" long and bent in a U shape. Cant find it in parts book, anyone know where it went?
Also, the rectifier, does this connect to ground through the frame? Wondering if I need to remove any paint where it mounts.

Thanks.
Title: Re: earth cable
Post by: martin_uk on March 18, 2015, 10:22:23 PM
Rectifier needs to be earthed at mounting point, I normally add an extra earth lead to be sure.
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 09:07:33 AM
I was thinking about the rectifier.
Surely it cant earth through the mount as the whole battery box is insulated from the frame by the mounting rubbers.
Title: Re: earth cable
Post by: tom400f on March 19, 2015, 11:00:05 AM
Is there not an earthing wire for the battery box that goes under one of the mount screws?
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 11:35:19 AM
Maybe, maybe thats what my extra cable is for. Where does it go?
Title: Re: earth cable
Post by: Lobo on March 19, 2015, 11:46:46 AM
Hi Graeme,

Unsure... assume we're talking 750 K series? (I am!)

I can't find any specifics as to the positioning of the main frame earth, but for ease of servicing have bolted mine on the outside of the mounting bolt. In my pic below it is taped up ...

Might be confused (ie myself), but your rectifier is earthed via its connector plug into the loom of the bike. (Green). This green then appears elsewhere and is bolted to the frame - LHS panel, top LHS.) See attached pic with single scrawled circle. Its a REALLY CRAPPY photo - sorry - but there is a (green) earth eyelet bolted (outside) and going (initially) vertically down before looping up to the right. (& nothing to do with the #1)

Your spare 5" earth cable... is it a heavy duty one.... and actually the +ve from the battery to the solenoid?

A pic of my K2s battery area, fairly accurate methinks.
Simon
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 11:59:54 AM
My bike is an f1.
The rectifier does earth through a green wire though. The only place I can see that green connectsbto the frame is up by the coils.

I have the solenoid to battery cable fitted. The spare cable is just like that one but has set in a u shape. Maybe its not stock.
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 12:01:42 PM
This is the cable.
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 12:03:39 PM
This is my wiring so far.
I would have put pics up earlier but there is a size limit and ive only just worked out how to change size.
Title: Re: earth cable
Post by: Lobo on March 19, 2015, 12:13:16 PM
From that photo the rectifier loom plug does seem to have a green... confused.

Just found this pic for the K series... luckily my earth strap correct. Wouldn't have thought the F would be different.

Simon
Title: Re: earth cable
Post by: Lobo on March 19, 2015, 12:17:26 PM
I appreciate the following is not a lot of help.... I was looking through the F1 difference wrt your rectifier earthing... but it's says nothing... implying the set up is the same???

Anyways,
Title: Re: earth cable
Post by: Lobo on March 19, 2015, 12:25:23 PM
Still confused Graeme.

In your photo you've the fuse holder connector lowermost, and above it the rectifier connector. In the wiring diagram (my last post) these two connectors are reversed, ie the rectifier is lowermost. And it has a green wire.... (+ 3x Yellow + Red/White) which presumably is connecting into the bikes loom, and thence an earthing point somewhere?

At the mo can't think of what your spare 5" heavy duty cable might be, but by the eyelet sizes am wondering whether the PO connected the battery earth to a nearer point on the frame rather than the standard engine hanger bolt?

Simon
Title: Re: earth cable
Post by: Lobo on March 19, 2015, 12:38:11 PM
...just checked the DSS website... His reg / rectifier is a combined aftermarket part... same # for both 750 K & F series. Notably this part has the standard loom connector with included green earth wire.

So, I'm confused... and will have to bow out on this one!

Oh... that 5" strap??? its shape looks awfully like it connected the batt -ve to the forward most R battery cradle mount in your pic!

Simon.
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 01:56:01 PM
Battery to battery box mount is what I thought. My main earth is good though so ill leave the extra one out.
that drawing helps too. Ive put the multi connectors in the wrong holders. They fell easier that way as I ran the wiring behind the fuse box.
Its not right, but neat enough and should all work.
Thanks for the help :)
Title: Re: earth cable
Post by: martin_uk on March 19, 2015, 04:38:55 PM
Here is my F1, used a star washer on rectifier mount plus extra earth

(https://farm4.staticflickr.com/3867/14483427469_82714880f2.jpg) (https://flic.kr/p/o4RmoH)2014_0716brakes0037 (https://flic.kr/p/o4RmoH) by nitram2010 (https://www.flickr.com/people/46578358@N07/), on Flickr
Title: Re: earth cable
Post by: Graeme77 on March 19, 2015, 05:08:13 PM
Where did you run the extra earth to? Was there a problem before you did this?
Title: Re: earth cable
Post by: martin_uk on March 23, 2015, 08:40:16 AM
Where did you run the extra earth to? Was there a problem before you did this?

The extra earth runs to negative on battery and another extra earth to one by coil mounting.

Its covered with black sheath and crimped non insulated 6mm ring terminals with a piece of heat shrink to tidy up, so is unobtrusive.

My concern was to make sure the rubber mounted battery/rectifier bracket was fully earthed.

Mainly a precaution based on previouse experience of earthing problems, which can be a pain.
Title: Re: earth cable
Post by: AshimotoK0 on March 23, 2015, 09:32:20 AM
The black and white photo, Simon posted, shows the bare braided K0  earth cable. These are mega rare now NOS and the Yamiya repro, although cheap enough is sh*te. Second hand ones are always tarnished or totally sha**ed.  I have done an 'anatomy' of the original (hundreds of tiny tinned copper wires inside a braided tinned copper sheath) and I am having some brass, then tin plated,  terminals laser cut to make a  proper repro of this part. Will be a few weeks yet before I have a sample. The later cables are made from the typical PVC sleeved, high current,  cable, common to earlier Hondas. I have made a test setup to check the integrity of the soldering of the hundreds of wire cores. This consists of passing a calibrated  100A DC pulse down the finished cable and measuring the voltage drop (mV).

Ash
Title: Re: earth cable
Post by: Lobo on March 23, 2015, 01:01:43 PM
...put me down for one Ash... funds up front if you want 'em.

Simon
Title: Re: earth cable
Post by: JamesH on March 23, 2015, 01:29:31 PM
Yep me too Ash...