Ross’ 1975 CB750

[Galactica]

I took the CB750 over to the Island yesterday for a Celebration of Life.  Except for a GPS snafu, the bike ran flawlessly.  The clutch seems to be behaving itself so far.  Could well be that the plates were sticking.  I’ll keep you posted.

[Steve G.]

  GPS's act very odd when the motorbike is 40+ older than the GPS.

[Galactica]

Bit of an update.  The CB750 is running really, really well.

I finally got around to getting a match for a modern paint.  Honda Planet Blue matches really close to Ford B3, Atlas Blue.

[Galactica]

So, at coffee last Wednesday we were talking charging systems.  Mrs. Wheels is having issues with the charging on her ‘81 CB650C.  It brought to mind the system on my CB750. 

The system on my CB750 has a separate rectifier and regulator.  What I’ve found on the interweb is that my bike charges at 12.4v@2,000rpm, 13.2v@3,000rpm, and 14.5v@4,000rpm.  That jives with my own checks.  So essentially it’s not charging at idle.  Given that it’s charging as it should from the factory, and I’ve had zero starting issues, is there any advantage to installing a new integrated reg/rec unit?  ie, would it charge better at lower rpm?

[Steve G.]

IMO, I wouldn’t bother. While your charging system is easily considered archaic, so is the regulator/rectifier  heat sink system, compared to modern charging systems in the automotive industry going back 25 years.  Most older machines,,,,I’m assuming your Honda included , have an on/off headlight and running light handlebar switch,  which is there for a reason, during startup and low rpm warmup.
  I replaced the charging system on my Norton because it’s charging system  is even more archaic than yours, with heat sink zener diodes placed on the side Z plates, which works fine until one zener decides it does not want to perform EXACTLY the same resistance as its performances match  partner on the other side,  which then  makes one try to take more excess electricity than it’s able, which causes death of the diode, and then the other, followed by overheated battery and overheated stator. My current setup using a Podtronics  solid state universal reg/rec  3 phase unit has worked admirably for 25 years, releasing g an exact 13.8 volt maximum steadily, the unit capable of negative ground, positive ground . I probably should have bought one of these for the Laverda during my recent charging issues with it.

[Galactica]

By all accounts, the axiom “if it ain’t broke, don’t fix it” applies here.  It seems that charging doesn’t change with installation of an aftermarket reg/rec unit.  So unless, and until, the original regulator/rectifier system fails, I’ll keep it as is.

[hardrockminer]

There may be a screw on your regulator that allows you to vary the voltage a bit.  You could probably get a bit more at lower rpm's but it would then charge at too high a rate at higher revs.

[Galactica]

So, the other day I had the left side cover off to poke around with the regulator/ rectifier.  I had a bit of trouble getting it off. I guess I didn’t get it pushed back on properly.  I lost it somewhere on the freeway on my way out to coffee in Ft. Langley yesterday.  Dang.  Oh well, replacement cover and emblems are ordered.  I still have enough pain left over to get the new one painted. 

I’m having shoulder surgery August 1st so probably won’t be riding the CB750 until spring, so today I began bedding her down for a few months.  I’m hoping to get do a run with the Tracer900 up to Sicamous Sunday, returning on the 31st.  I’ll try to leave Sicamous early enough that I can get home and bed down the Yamaha that evening prior to my surgery the next day. 

In any case, that’s pretty much it for my motorcycling for this year, most probably until spring. 

[kilowop]

Think positive.  You have the CB-750 sitting, just waiting for you once you feel up to giving it more TLC.  The Yamaha should be good to go come spring if you put it away correctly.  Modern machines are pretty good that way.
Good luck with your surgery. I had similar done back in '08, and after about 6 months of rehab was back on a bike for short runs.

[Galactica]

So I have replaced the side cover.  Cost me $300.

[Steve G.]

  I can’t stop thinking of a perfect side cover skittering down the highway,  then crunched by a gravel truck tire.

[Bucko]

Ross:  Somewhere in my heaps of junk, I have a bag of glue on plastic 'plugs' with lanyards attached.  They're perfect as a back-up for securing side covers (that's why I bought them).   You're welcome to have some if I can find them. 

[Galactica]

Ross:  Somewhere in my heaps of junk, I have a bag of glue on plastic 'plugs' with lanyards attached.  They're perfect as a back-up for securing side covers (that's why I bought them).   You're welcome to have some if I can find them. 

That would be great Dave.  Probably need just for the left side.  The right side can’t come off if the oil dip stick is in place.

[Galactica]

Ok.  I’ll try to post a couple of my collector plate photos.

[Galactica]

Woo Hoo!!  I did it.  It’s a bit of a process.  If only I’ll remember how to do it next time.