Topic: My first complete build 72 CB750 - completed for now...

[754]

Get a set of 77 /78 F Forks  will fit in your trees, much easier to adapt newer brakes to.
 Will use your axle and you can run your wire front wheel and put Duc or Yam big floaters onto the stock hub. Then mount up calipers.   You will need drill press or a milling machine.
 The pic shows a Morris wheel, a replacement for the stock wheel, using F forks.

[algophobe]

Get a set of 77 /78 F Forks  will fit in your trees, much easier to adapt newer brakes to.
 Will use your axle and you can run your wire front wheel and put Duc or Yam big floaters onto the stock hub. Then mount up calipers.   You will need drill press or a milling machine.
 The pic shows a Morris wheel, a replacement for the stock wheel, using F forks.

it works with stock 1972 hubs as well? same clearance issue with dual piston calipers?

[algophobe]

so I had a chance to look at the spark plugs, a little dark but not too bad. all sparks fires well. I restarted the bike and she runs normal now. now im really baffled. could it be a temporary short somewhere? the Antigravity Li battery wasn't even charging after that ride, therefore I figured it was tapped dry. but I put a volt meter on it and it red about 9 volts and is charging now.

[algophobe]

my question is, does running on 2 cylinders lower the charging capability of the alternator, therefore causing premature battery failure?

Its probably the other way around. Low voltage from the battery will cause the ignition not fire all 4 cylinder equally. I'd say you have a charging issue causing the battery drain, and you may have an ignition/carb issue. You can't sort out the ignition/carb issue until you get the electrical system 100%.

Your AG battery at 9v is a strong indication of a dead soldier. AG's don't tolerate over-discharge. It may charge up, but it won't hold up. They are also susceptible to expanding and exploding due to over-charge and over-discharge. Be very careful from this point with that battery.

Your plugs look "wet" to me from the limited picture. If those are from your general ride, you need to get 4 fresh plugs, and perform an IDLE chop, then a WOT or 1/2 Throttle CHOP. Reading plugs from general all-around riding is superfluous.

When you refer to the dead solder your referring to the internals of the battery, not the wiring leading up to it correct? It charged up to 14V and i left it off its trickling down to 13V after 12 hrs. I would necessarily trust that battery and I'm working with a AGM right now to sort out the electricals.

I've never done the chop maneuver but I'm assuming the idle and wot chop you're referring to is to shut off the engine abruptly and check the spark plug coloration?  So much to learn!!! Thanks in advance Cal

[754]

Here is a shot of a conversion I did wire wheel like yours on F forklegs, i think calipers are Honda
And rotors maybe VFR.. I did it  for Bert in Montreal.
 I have a set of caliper adaptors and I think calipers.

Here is another I did, trees a bit narrower than cb750.
That is an 18 inch Yamaha mag, it has greater clearance to caliper than most wheels, the 19 in should as well.

[algophobe]

So i got the replacement top triple from cognito. It was vapor blasted prior to anodizing to get rid of the mill marks... a lot more matt black than expected. Not sure which i like better

[algophobe]

so I ran the test that you suggested Cal, based on this conversation thread

http://forums.sohc4.net/index.php/topic,174516.0.html

I set up the Aux2 to be on with the key turned on, equivalent of "lock" or "ignition"
Battery voltage 12.43
engine idle: voltage @ battery 12.43, @ lock (or Aux1) 12.35
engine idle (with lights) @ battery 12.16, @ Aux1 11.88
engine idle (with high beam) @ battery 12.12, @ Aux1 11.98

running it at 4000 rpm doesn't change it much.

then voltage between the black RR and batter positive with the key "on" without engine running gave a difference of 89 mV.
but i'm not sure what the difference between measuring voltage difference between the black RR wire and pos battery vs. measure from Aux1/lock and pos battery would be, since the black RR wire does into the m unit to obtain voltage reference.

check my setup... these numbers don't necessarily point to the cause of the bike stalling.

[algophobe]

The Black RR -> POS terminal shows the loss through the harness of actual battery voltage and what the RR is seeing. It is consistent with what the difference is at AUX and battery. So, you've got a couple of problems somewhere.

First, the RR should be over-charging, not static. That makes me think you have a ground issue from the battery/RR. In the picture, it looks as though the battery - cable ties to the M-Unit, and nowhere else? It needs a solid connection to the motor and frame. You can then run a ground from M-Unit to battery -. But you need the other leg.

I see a loose Black wire with a ring terminal dangling on the near side. Curious, what is it for?

Make sure the battery gets a clean metal ground between the frame and motor. Make sure the RR ground to battery is tight. Run a ground from MU to battery -.

On my 550 (first MU install a few years back) with a Ricks, I never got great charging due to using rivet nuts and new "ground screws" until I finally moved the battery NEG to the stock location, AND ran the MU to - wire. Since then, my 550 charges over 13v by 2500, never more than 14.2v at 5000.

so the 89 mV is significant then, or at least the difference between the battery and aux1?

also when you refer to "the RR should be over charging, not static", I'm assuming you are expecting reving to 4000 rpm should produce a jump in voltage?

the battery - goes to the M unit, which is bolted thru and thru to the electrical tray which was welded to the frame. I don't have a (-) to the engine (I guess that would need to be remedied, you would recommend a direct battery (-) to frame and engine?).

the RR - wire (green) is currently grounded thru the other mounting bolt on the M unit (to the left).

the loose negative is just to the trickle charger (both + and -) are detached, and is unplugged. I routed it under the frame for easy connection to the charger with the cowl on.

on a side note, black oxide bolts should conduct well shouldn't it?

[algophobe]

The difference of to the Regulator is seen in the reading between AUX and battery directly. That means the Regulator is getting a false reading, but not producing the added charge needed. That’s an indication you’re not charging accurately, nor fully.

Yes, at 4,000 you should be over-charging due to the difference at AUX and battery.

Stock, the battery NEG is pinched on the upper right rear motor mount against the motor, between the mount and motor. The mount to the frame. Any paint or powder coating between these connections nistroduces resistance and less charge accuracy.

You an leave the RR Green on the MU, as long as you add the battery NEG leg to that terminal also.

Black oxide conducts better than rusty bolts, not as well as stainless or zinc. And they rust worse than stainless or zinc.

i'm in the process of the re-wiring the (-) as you suggest. do you think 14 gauge is adequate to run from the battery to the frame/engine mounting, and which bolt mount is the stock negative wiring to  (red or green arrow)?

if the MU Aux voltage (which connects to the RR via the black wire) supposed to fluctuate with varying RPM as it is the reference of battery usage to tell the RR to charge, whats the best way to test downstream of the RR to actually see if its doing its job? would you test at the RR RED WIRE? Because you mentioned that with your 550, you were getting reading of 13v and 14v at 2500 and 5000 rpm's, i'm curious where you place your red probe on the volt meter.

[algophobe]

So I got the ground rewiring done:
1. M unit directly to battery -
2. battery - to frame in electrical tray, then jump to engine/frame mounting point.
3. RR- negative to the frame at the same electrical tray as well

noticeable fluctuations from on to idle to 5k rpm:

@ aux: on 12.26, idle 12.28, 5k rpm 12.30 volts
@ battery: on 12.33, idle 12.33, 5k rpm 12.36 volts

its better than being static in previous setup, but I was expecting greater rise than 0.03 to 0.04 volt over charging.
then I switched to the Li ION battery (apparently its fine, still held charge and fires up the engine) so I did the same tests. seems to be a little better

@ aux: on 12.87, idle 12.88, 5k rpm 12.92 volts
@ battery: on 12.94, idle 12.94, 5k rpm 12.98 volts
@ battery with lights: idle 12.67, 5k rpm 12.71 volts

so there is still a drop off in voltage from battery to aux with power on using the AGM battery 12.33 to 12.26.
I check that the greatest from off was at the 15 A fuse placed between the + to the M unit, with some loss within the M unit itself...
would it then be wise to take out the 15A fuse? doesn't the M unit have it own internal "fuse"?

[algophobe]

Keep the fuse. It protects the M Unit from external evil forces.

You are still not charging. Your voltages with the engine running are too low.

Base on the stock wiring there is a 15A fuse between the battery and the ignition however no fuse between the RR and the battery red wire. Could this make a difference? Other option is getting a different RR. Or issues with field or stator coils. I tested them for continuity and resistence early in the build and seemed fine.

[algophobe]

No, the lack of a fuse is not the issue.

Do yourself a favor and follow this diagram and identify the exact cause of your issue.
https://cdn.shopify.com/s/files/1/1091/5694/files/fault-finding-diagram.pdf?235929069374954073

It’s super easy, very detailed, and always produces the correct answer. You need a meter and a charged battery, and the ability to read 

I can do that! This is exactly what i need. Thanks Calj

[algophobe]

HAPPY THANKSGIVING EVERYBODY!
The beauty of going to someone else's house for TG dinner is you have time for tinkering instead of prepping for the dinner. Finally had some time to work on the bike.

I found the culprit! I can't believe I didn't see it previously. probably because one of the yellow wire was on the underside of the block connector. The whole time I was focused on the RR/Munit/battery side of the problem. Two of the yellow wires coming from the stator burned out. one at the block connector, the other at the bullet connector.  I salvaged these wires from the wire loom purchased from Sparkz  Moto (yellow wires bottom). seem like a lot of insulation but not much wires. Fortunately the rest of the harness that I built were using quality wires from Revival (orange wires on top). seemed like the wire is kinda small for wires used for the generator. Even thought the problem was obvious, it sure helped to approach it systematically... Thanks CalJ for the "Charging systems manual for Dummies".

I followed the flow chart and performed the remainder of the tests that doesn't require the burnt interconnecting stator yellow wires. Stator/Field coils work fine, though the resistance for the field coil is a little high @ 7.9 Ohms, the flow chart wants it between 4-6 Ohms, but repair manual states 7.2 is ok. RR checks out well and all lines acceptable voltage drop.

now to find quality wires for the stator coil. what's the recommended gauge wire for these things?

[algophobe]

well the new segment of the wire harness is done, I used 14 gauge wires to connect from the stator to regulator. she charges beautifully to 14.5 volts at 5k rpm. maybe CalJ or one of you experts could chime in on why the stator wires fried. my amateur theory is this (the scientist in me has to theorize):

the bike was running for 100 miles till two of the yellow stator wires fried. in early testing, it was noticed that the reference voltage that the RR sees were stagnant @ 5k rpm (false reading)after the failure occurred. because of this false reading, the charging system was over charging all the time and fried the wire since it was always getting low reference readings from the M unit and was unhindered by the RR. the battery would get trickle charged via outlet to retain its voltage in between early short testing rides, until the final failure. Then when I rewired the ground wire for both RR and M unit. I was able to see fluctuations in the charging (correct reading), but by this time only 1 stator coil was working. therefore the charging response was anemic.

all because of a bad ground wire (as mentioned by CalJ initially).
*insert wayne and garth line "we're not worthy! we're not worthy!"

[algophobe]

so she's completed for now. just a little update, I put about 120 miles on her since the re-wire. there were some issues with the rear signal light that had to be sorted out. the quality of the contacts on the leads going to the bulb wasn't the best but I modified it to work better. she runs well, just have to get a chance to do the spark plug chop a little later. i decided to submit my humble build to this year's Outlier's Guild Motorcycle Show just for the heck of it. Fingers crossed!

[SOHC4 Cafe Racer Fan]

See you at the OG Show.  I'll be helping Jay with the load in.

[algophobe]

See you at the OG Show.  I'll be helping Jay with the load in.

which Jay and which bike? do tell!

[SOHC4 Cafe Racer Fan]

See you at the OG Show.  I'll be helping Jay with the load in.

which Jay and which bike? do tell!

My buddy Jay LaRossa (Lossa Engineering) is one of the show's partners. I'm helping him with the load-in of the bikes.

[SOHC4 Cafe Racer Fan]

Your bike has been duly nominated and seconded for Bike of the Month (February 2019).  To be eligible for voting, please post that you "accept" the nomination in the following thread:  http://forums.sohc4.net/index.php/topic,175508.0.html

[algophobe]

Thats pretty awesome.. your involvement with the show and the nomination... I thought you were referring to j webster. I met him briefly at the 1st og moto show.

[SOHC4 Cafe Racer Fan]

Thats pretty awesome.. your involvement with the show and the nomination... I thought you were referring to j webster. I met him briefly at the 1st og moto show.

Well, I am not officially involved in the show.  Jay is one of the partners.  That said, I'll be helping load in bikes, having them photographed, and placing them in the space.  In exchange, Jay hooks me up with a VIP pass.  The best part is meeting all the builders.

[algophobe]

Thats pretty awesome.. your involvement with the show and the nomination... I thought you were referring to j webster. I met him briefly at the 1st og moto show.

Well, I am not officially involved in the show.  Jay is one of the partners.  That said, I'll be helping load in bikes, having them photographed, and placing them in the space.  In exchange, Jay hooks me up with a VIP pass.  The best part is meeting all the builders.

regardless, that's pretty awesome. maybe you can put in a "good word"  ... a special amateur section.
it always felt the LA area was voided of that particular motorcycle culture, needless to say I was stoked when the first OG show was put together.

[SOHC4 Cafe Racer Fan]

Thats pretty awesome.. your involvement with the show and the nomination... I thought you were referring to j webster. I met him briefly at the 1st og moto show.

Well, I am not officially involved in the show.  Jay is one of the partners.  That said, I'll be helping load in bikes, having them photographed, and placing them in the space.  In exchange, Jay hooks me up with a VIP pass.  The best part is meeting all the builders.

regardless, that's pretty awesome. maybe you can put in a "good word"  ... a special amateur section.
it always felt the LA area was voided of that particular motorcycle culture, needless to say I was stoked when the first OG show was put together.

Up to 3 years ago, LA was definitely lacking a top-shelf custom builder show similar to the One Moto Show (Portland, OR) and the Handbuilt Show (Austin, TX).  Given the number of builders, riders and enthusiasts in Southern California, there was a market for show here.

Kevin Dunworth and the House of Machines also did a small invite-only show for 21 bikes this last summer - the Golden Bolt Show - in Los Angeles.  The bikes featured were top notch, but the event could have been promoted better, and it was pretty much limited to just those bikes.

The Outlier's Guild (OG) Moto Show will feature a number of invited pro builders (bikes displayed on platforms), with other bikes submitted and approved for display, an area for motorcycle art (photos, sculpture, media), selected vendors, food and beverage, music, etc.  The invited pro built bikes feature some of the best builders in the country (e.g., Max Hazan, Woolie, Cristian Sosa, Kiyo, Shinya, Suicide Machine, Brandon Holstein/Speed Merchant, Justin Webster).

Check out the photo galleries from the last 2 years: http://www.ogmotoshow.com/media/

[algophobe]

Good news, my submission to Outlier's Guild Moto Show in late March was accepted! Its not in the main hall next to invited builders by any means but heck I display my build for a free ticket into the show.

[SOHC4 Cafe Racer Fan]

Good news, my submission to Outlier's Guild Moto Show in late March was accepted! Its not in the main hall next to invited builders by any means but heck I display my build for a free ticket into the show.

Great! I'll be at the load in so stop by and say "Hello."

Don