Upgrades for charging system? ‍♂️ cb750 dohc

88SS

Active Member
Are there any charging system "upgrades" or cheats for the cb750 dohc?

I've seen some ignition switch bypasses, but other than that......

I have replaced the whole shabang this year. R/r battery, stator, and the ignition switch. My fear is I'm already seeing symptoms of a failure. I'm planning a long trip on the bike, and I would like to have a smooth ride. A little peace of mind in this area would be awesome.

Any tricks? Low watt bulbs or anything.... I'm all ears!!


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I found this over at cycle x. Anyone have any experience? Sounds pretty tempting

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hillsy said:
What "symptoms of failure" are you seeing?

I haven't put a multi meter to it yet, but I'm having to trickle charge the battery before I ride on the weekends. Also, the lights dim when I brake. I've been working on the carbs and riding in traffic more lately, so I think all the heat and idling has weighed heavy on it.

After I replaced everything, I didn't have any problems. Now I'm starting to see the battery slowly drain. I fear it's the beginning of the end.

Another thing I noticed was not being able to break past 7,000 rpms all the time. Never had that issue before. Even when the carbs where out of tune I could still get the rpms up higher. Plugs are good. Coils and wires are new.

I know this is a dated system for charging, and when it does crap out I would love to replace it with something that will last.

The cycle x kit is actually priced pretty good. I'm thinking that and an oil cooler will help with traffic situations. What are your thoughts?

I absolutely love the bikes original glory, but I can't help but think of improvements


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Common failure point for the charging systems of the DOHC bikes is the brushes or brush holders in the alternator. Check both over. The brushes are easy to come by, but the holder is not.
 
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Sonreir said:
Common failure point for the charging systems of the DOHC bikes is the brushes or brush holders in the alternator. Check both over. The brushes are easy to come by, but the holder is not.

I checked them. Your right about the holder.
I've got a new set, but I may have to solder the dog legged one to make it work. I ordered two separate sets, and neither one came with the right one.

Will a solder job even work?

Both of the installed brushes are still above the indicator. The dog legged one is shorter however


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Electrically a solder job should work. Mechanically will depend on how much vibration it sees.
 
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Sonreir said:
Electrically a solder job should work. Mechanically will depend on how much vibration it sees.

I found one online. It was a little pricey, but came in the mail lightning fast. I replaced it. 95 percent sure that it's fixed.

Lights don't seem to be dimming anymore


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Charging system shit out on me again. I got almost a year out of it. This time I’m upgrading to the cycle x charging system. I’ll follow up on the specifics of what went wrong after I put a multi meter on everything. The good news is: I was packing to take a trip last weekend. Charging system went out the day before lol. Win some and lose some.


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Is it truly the charging system or just a run of shite batteries? I've had both and the symptoms tend to be the same or similar.
 
coyote13 said:
Is it truly the charging system or just a run of shite batteries? I've had both and the symptoms tend to be the same or similar.

I’ve been working out of town, so I haven’t had a chance to work on it. First order of business is to get a new battery and then put a multi meter on it. The battery definitely kicked the bucket, so that could very well be it. I suspect it’s not because one day it was fine and the next it was dead. I’ve been keeping the battery on charge as well.

Either way I’ll update this weekend with some results. Also, I was already planning on switching to the cycle x system anyway just haven’t gotten around to it. Im going to go ahead and upgrade to their ignition system as well. Ken at cycle x says he uses the gold old lead acid batteries, but I’m real curious about lithium ion. Any experience?

I’ve seen them swole up like a pumpkin. I’m not looking throw away 200 bucks.

I’m reading that overcharging is an issue, but wouldn’t the reg/rectifier prevent that, or do I need a battery with the built in safe guard?


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Put the multi meter on it today, with a fresh battery. Voltage drops when reving. Looks like the the r/r is toast


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88SS said:
Put the multi meter on it today, with a fresh battery. Voltage drops when reving. Looks like the the r/r is toast


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Ditch the regulator and rectifier for the solid state unit. It cured most of my charging issues.


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Thought I would post an update:

I bought the cycle x charging system, which comes complete with a solid state unit. It’s a very nice set up. Super simple to install. I had to dive a bit further into the electrical than normal, but it wasn’t bad. Also got a good battery (with a 2 year warranty).

At first I wasn’t impressed. I fired the bike up, and it was running like crap. Carbs started pissing gas. All the typical crap. So I’m scratching my head.... then I got the multimeter out and poked around. After a bit, I decided to go back and rewire the yellow wires. Fired it up and it was charging.

With the carbs still pissing gas, I decided to go “Italian tune up” route. After a fresh tank of gas and about 20 miles, everything cleared up and WOW.

Night and day difference. It’s hard to describe, but there’s less vibration, the ignition seems to be working better, and the revs rise and fall quicker. I swear I can feel the weight reduction on the right side as well


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88SS said:
Thought I would post an update:

I bought the cycle x charging system, which comes complete with a solid state unit. It’s a very nice set up. Super simple to install. I had to dive a bit further into the electrical than normal, but it wasn’t bad. Also got a good battery (with a 2 year warranty).

At first I wasn’t impressed. I fired the bike up, and it was running like crap. Carbs started pissing gas. All the typical crap. So I’m scratching my head.... then I got the multimeter out and poked around. After a bit, I decided to go back and rewire the yellow wires. Fired it up and it was charging.

With the carbs still pissing gas, I decided to go “Italian tune up” route. After a fresh tank of gas and about 20 miles, everything cleared up and WOW.

Night and day difference. It’s hard to describe, but there’s less vibration, the ignition seems to be working better, and the revs rise and fall quicker. I swear I can feel the weight reduction on the right side as well


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I have a 1982 Honda CB 900F. Sick of the charging issues so i have a Cycle X unit on the way. How difficult was the wiring?
 
VintageMBike said:
I have a 1982 Honda CB 900F. Sick of the charging issues so i have a Cycle X unit on the way. How difficult was the wiring?

Not at all. It’s only 5 wires. Buy some connectors and a little extra wire. Stock Honda wiring: green is ground, red/white is power, then connect the yellow wires and your in business. Very simple set up, and I could actually tell a difference immediately. Seems like the smaller size rotor creates much less vibration


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