Topic: 750 K4 Battery Ground to Engine Case or Frame?

[pickleknuckles]

My K4 750 has what looks like a stock ground wire from the battery to a rear case bolt under the output sprocket cover. Is this correct?
I can't find any info other than people commenting on grounding at the rear right engine mount/frame, or some random pics of earlier 750s that used a braided strap to the left rear mount/frame. The back half of the harness is also pretty hacked up from the previous owner and none of the original battery cables are there other than this so I'm not 100% on it.
Thanks.

[Johnie]

Honda secured it by a bolt through the left frame/case at the bottom of the left side cover area. Sorry I don't have a close-up, but if you look at the bottom of the left side cover towards the front you can see the ground strap bolt. Click the pic to enlarge it. I see you are a new member and first post...welcome to the board.

[HondaMan]

And, like Johnie says, but with this mention: avoid putting that ground under the bolt-head - it belongs between the engine and the frame bolster. The inside of the bolster should be clean (as in, no paint, that's how Honda made them) and the 1mm of that cable lug's thickness is the 'spacer' between the engine and the frame to ensure there is no twisting torsion across the swingarm bolster, which is right behind it. This is often overlooked and minor, until you approach a turn at 90+ MPH. Then, it matters as having it installed the wrong way actually pitches the rear wheel toward the right slightly, even when the chain indicator marks are 'equal' at the rear axle.

I can explain how to measure this trivia, if you care?

[grcamna2]

subscribed

[newday777]

My K4 750 has what looks like a stock ground wire from the battery to a rear case bolt under the output sprocket cover. Is this correct?
I can't find any info other than people commenting on grounding at the rear right engine mount/frame, or some random pics of earlier 750s that used a braided strap to the left rear mount/frame. The back half of the harness is also pretty hacked up from the previous owner and none of the original battery cables are there other than this so I'm not 100% on it.
Thanks.

Welcome aboard the forum pickleknuckles
The cable coming out of the motor at the sprocket cover is the starter positive that connects to the starter relay (on the left).
It is not a ground as you thought.

The ground attachment to the frame is at the rear engine mount bolt comes directly from the battery, that is commonly seen on it the outside of the frame(as Johnnie said).

Next step, go to the new members section and introduce yourself and your bike.
Also, where your bike is a work in progress, go to the project section and start a new post on your bike there, post what your bike is, how you got it and when, keep your progress as you go along on it and to keep all your questions on it together in that thread so we all can follow along. Pictures are always good for all to see, and the thread can help others learn if they don't know. We all like tinkering.

[newday777]

And, like Johnie says, but with this mention: avoid putting that ground under the bolt-head - it belongs between the engine and the frame bolster. The inside of the bolster should be clean (as in, no paint, that's how Honda made them) and the 1mm of that cable lug's thickness is the 'spacer' between the engine and the frame to ensure there is no twisting torsion across the swingarm bolster, which is right behind it. This is often overlooked and minor, until you approach a turn at 90+ MPH. Then, it matters as having it installed the wrong way actually pitches the rear wheel toward the right slightly, even when the chain indicator marks are 'equal' at the rear axle.

I can explain how to measure this trivia, if you care?

Mark
I've read that before a couple years ago and forgot about that needing to be put between the motor and frame rather than the outside of the frame as it is commonly seen. Did they come from the factory between the case and the frame?

[ekpent]

And, like Johnie says, but with this mention: avoid putting that ground under the bolt-head - it belongs between the engine and the frame bolster. The inside of the bolster should be clean (as in, no paint, that's how Honda made them) and the 1mm of that cable lug's thickness is the 'spacer' between the engine and the frame to ensure there is no twisting torsion across the swingarm bolster, which is right behind it. This is often overlooked and minor, until you approach a turn at 90+ MPH. Then, it matters as having it installed the wrong way actually pitches the rear wheel toward the right slightly, even when the chain indicator marks are 'equal' at the rear axle.

I can explain how to measure this trivia, if you care?

Mark
I've read that before a couple years ago and forgot about that needing to be put between the motor and frame rather than the outside of the frame as it is commonly seen. Did they come from the factory between the case and the frame?

I've seen them that way.

[MauiK3]

I have also seen this

[pickleknuckles]

The cable coming out of the motor at the sprocket cover is the starter positive that connects to the starter relay (on the left).
It is not a ground as you thought.

It's not tho. If you look closely at my pic, I actually have three cables coming out from under the sprocket cover. The starter wire, the stator bundle, and this ground which is attached to the case bolt under the boot at its end. Not seeing this particular detail on other K series bikes is what got me wondering if it was correct in the first place

Welcome aboard the forum pickleknuckles

Next step, go to the new members section and introduce yourself and your bike.
Also, where your bike is a work in progress, go to the project section and start a new post on your bike there, post what your bike is, how you got it and when, keep your progress as you go along on it and to keep all your questions on it together in that thread so we all can follow along. Pictures are always good for all to see, and the thread can help others learn if they don't know. We all like tinkering.

Thanks for the welcome, and will do!!

[pickleknuckles]

And, like Johnie says, but with this mention: avoid putting that ground under the bolt-head - it belongs between the engine and the frame bolster. The inside of the bolster should be clean (as in, no paint, that's how Honda made them) and the 1mm of that cable lug's thickness is the 'spacer' between the engine and the frame to ensure there is no twisting torsion across the swingarm bolster, which is right behind it. This is often overlooked and minor, until you approach a turn at 90+ MPH. Then, it matters as having it installed the wrong way actually pitches the rear wheel toward the right slightly, even when the chain indicator marks are 'equal' at the rear axle.

What part are you referring to as the "bolster"

I can explain how to measure this trivia, if you care?

I am actually very interested. I've never been able to get my rear wheel aligned...tho it appears misaligned to the left a bit.

[newday777]

The cable coming out of the motor at the sprocket cover is the starter positive that connects to the starter relay (on the left).
It is not a ground as you thought.

It's not tho. If you look closely at my pic, I actually have three cables coming out from under the sprocket cover. The starter wire, the stator bundle, and this ground which is attached to the case bolt under the boot at its end. Not seeing this particular detail on other K series bikes is what got me wondering if it was correct

The heavy 8 ga cable with the black cap on the end should not be connected as a ground to the motor.  If it is someone has done it and your starter won't work.

[grcamna2]

The cable coming out of the motor at the sprocket cover is the starter positive that connects to the starter relay (on the left).
It is not a ground as you thought.

It's not tho. If you look closely at my pic, I actually have three cables coming out from under the sprocket cover. The starter wire, the stator bundle, and this ground which is attached to the case bolt under the boot at its end. Not seeing this particular detail on other K series bikes is what got me wondering if it was correct

The heavy 8 ga cable with the black cap on the end should not be connected as a ground to the motor.  If it is someone has done it and your starter won't work.

That looks like the starter power+ cable.

[ekpent]

Yep - that cable goes straight to the solenoid.

[grcamna2]

I don't like that someone hooked that up to use as a Ground/Neg. cable..

[pickleknuckles]

The heavy 8 ga cable with the black cap on the end should not be connected as a ground to the motor.  If it is someone has done it and your starter won't work.

It actually worked fine this way and ran perfectly up until late 2001 when the bike was parked. The starter cable is still hooked up from the solenoid to the starter. The cable from the battery to the solenoid is missing, and I can't recall what happened to it...not sure if I removed it after the accident for some reason or if it just wasn't there at all. There is however a thin red wire w/a large loop terminal and an inline 20A fuse that is attached to a blue wire and then attached to a covered red/white, as well as a white wire w/a similar loop terminal that is attached to the thin black on the solenoid. The two loop terminals and the heavy black ground were all attached to the battery in some way.

The green/red wire from the right hand control is also attached to a length of non-original red wire that is ziptied to the main harness all the way to an original bullet connector on a black wire near the battery box location - the red wire from the Dyna S ignition is tapped into it.
No clue what all is going on w any of it, it's the way it was when I got it and it was always super reliable and never had any starting issues.

I have a new harness and both battery cables on order so I'm going to install it and then add the electronic ignition back in as shown in the Dynatek instructions. My main concern is getting the battery ground hooked up properly.

[pickleknuckles]

Yep - that cable goes straight to the solenoid.

It doesn't tho. It's attached to a bolt in the case. The line from the starter is there and it's attached to the starter at one end and the solenoid at the other. The line from the battery+ to the solenoid is completely missing.

[ekpent]

Oh sorry I did not notice that extra ground coming off the engine there.

[Don R]

 Someone has made a modification that's difficult to see in your first picture. That boot looks like the hot + cable cover. I need to get a good crimper and make some more battery cables, Many of ours are not well insulated and have work hardened copper inside. 

[grcamna2]

I'd like to see your new - cable/Ground- strap's lower ring terminal from the battery get connected/pinched between the top/rear steel motor mount to engine case after the metals are all shined-up on either side of the lower Ground- strap/cable's ring terminal and dielectric grease applied to keep it clean from corrosion.

[HondaMan]

And, like Johnie says, but with this mention: avoid putting that ground under the bolt-head - it belongs between the engine and the frame bolster. The inside of the bolster should be clean (as in, no paint, that's how Honda made them) and the 1mm of that cable lug's thickness is the 'spacer' between the engine and the frame to ensure there is no twisting torsion across the swingarm bolster, which is right behind it. This is often overlooked and minor, until you approach a turn at 90+ MPH. Then, it matters as having it installed the wrong way actually pitches the rear wheel toward the right slightly, even when the chain indicator marks are 'equal' at the rear axle.

I can explain how to measure this trivia, if you care?

Mark
I've read that before a couple years ago and forgot about that needing to be put between the motor and frame rather than the outside of the frame as it is commonly seen. Did they come from the factory between the case and the frame?

Yep, they sure did.
In 1980 (or maybe it was 1981) I was chasing a handling problem on a friend's 750K4. He had removed the engine to fix some broken fins and put it back in with the cable on the outside of the frame instead of between the frame and engine. He brought it to me, complaining that he used to be able to ride it with just 2 fingers holding the throttle (he had a lighter spring on the carbs) but after this engine-out event the bike "felt unfriendly" and couldn't be ridden without a firm grip on the bars. I rode it briefly and he was right. I did first the usual "string alignment' trick to see if the wheels were parallel: they weren't despite the chain adjuster marks being dead-on. Then I happened to notice where the battery cable was, put it back like it was from Honda, then loosened the swingarm bolt, too, and retorqued it after tightening down the engine. It immediately solved the issue, making the bike 'feel' like it was prior.

It is important to note that many of the pre-K5 bikes have the wheels running parallel with each other when the chain marks are aligned, but NOT NECESSARILY running on the same track. This happened because of the 3.5mm offset front wheel that appeared when the front axle hub was turned on the right side to accept a 2nd disc brake so that Honda could run 2 discs at Daytona in 1970 (when Dick Mann won it). In those days, the Daytona rules for "production racing" bikes meant that a customer must be able to walk into a Honda shop (or whatever brand of bike was raced) and buy the same bike that was run at the race. The K0 early front hubs were only machined on the left side for one disc, so Honda issued an urgent change to have the hub made 3mm wider and both sides cut flat to accept another disc, using 8mm (later 10mm) longer bolts to mount the discs. The mirror-imaged right  fork lower was also implemented in production instantly that week. But...the guys who laced up the front wheels didn't get a change notice, so when the new hub and spokes arrived, the wheels were still trued to the old spec until sometime late in the K4, which puts the front wheel 3.5mm to the left of center so as to align the left disc thru the middle of the left disc's caliper, making the disc parallel with the faces of the caliper (and yeah, the right caliper was at quite an angle to the disc there!). The original caliper arm hanger (the "C" hanger) could then be mounted on the right, with a few spacer washers, on the other leg and viola(!), 2 discs mounted using the same parts as on the left side. - however, this made the front wheel left-of-centerline of the bike's frame. Honda didn't do anything about this oversight until the Spring of 1974 when Motorcyclist magazine (which loved Brit bikes much more than Honda) pointed out that the bikes could "wobble their front end during downhill coasting situations with no hand on the bars..." (like someone rode that way?) and Cycle World pointed out that their 750K3 test bike would "drift to the left if the handlebars were released" in Fall of 1972. This wheel offset was the reason, so we all started relacing (sometimes requiring new, longer spokes on the left side of the front wheel) the front toward center. Honda fixed this for real in the 1975 CB750F0 and subsequent bikes.

During all this, we all started measuring the 750 (and the horrible Blue Streak Kawi 500, fully 1/2" off center at the rear wheels) and if the customer griped, relaced the front toward center and checked the rear, sometimes finding the ground lug on the outside of the frame instead of between engine and frame. After much (a whole Saturday) mounting and remounting that lug on a 750K3 I had handy circa 1974, I discovered that having the lug on the outside both compressed the frame inward at the top rear engine mount, adding increased binding force to the swingarm's pivot, and caused the rear wheel to become angled relative to the bike's centerline such that if I clamped a straight board on both sides of the rear wheel and set the front wheel parallel to the boards, the handlebars were pointed to the left a little bit. If I then put the lug back between engine and frame and remeasured, the handlebars were straight(er). This clued me in to why the bikes often 'pull' away from the throttle grip, but since the throttle spring is so strong, most riders never noticed they were also correcting the cross-steering issue: the wheels were parallel, but not directly in line. Relacing the front wheel toward center stops the pull, and often also stops the "headshake" reported by Motorcyclist mag.

[newday777]

That makes perfect sense. That took some time and thanks for taking the time to write it all out.

[HondaMan]

I probably should add this, to clear up the "buy a racer" premise for these bikes as 1970 Daytona racers: it was possible, if you had enough 'pull', to get a Yoshimura Racing Kit for the 750 to meet the definition of "buy the same bike". The racing kit was fabulous, including a whole new top end, optional 6-speed gearbox setup, CR carbs with 5 sets of jets, megaphone pipes, the extra disc/caliper, racing shocks and front-end parts, and your choice of clip-ons or flat handlebars. They even offered the fairing and an oil cooler (which Hooker copied within 2 months). You had the choice between 3 cams, too,  with hardened rockers and extra-strong valve adjusters. The oil jets in the new head had holes that were larger than the 0.0375" stock holes of the K0 (I don't know how big, but can guess), and the head used the old-style large oil jets. I've only seen bits and pieces of those kits in real life, but have met a couple of riders who managed to get 2 different versions and said they completely changed the bike. Both of them said the 6-speed box was flawless (one used the OEM clutch the other used the kit's clutch, no mention of troubles with either) and were close-ratio, and the chain oiler in the new countershaft was REALLY oily, dripping down the sidestand when the bike was parked after running. About the only parts that were OEM, they said, was the crankcases, which they both had welded the crankshaft oil separator studs into, mentioning those were a pain. But, the engine's serial number had to remain unchanged from the sale in order to qualify (and there were several privateers at that Daytona race who also didn't place or finish), so I guess that's one way to do it!?