Another successful Compufire 55402 R/R install (and happy GSer!!!!)

[Steedracer]

Thanks so much for everyone on this forum. All of the Stator papers, quick test (posplayr), and others, were so helpful. Bought the bike 6 weeks ago. After solving a starter clutch/possible loose crank nut issue that appeared on Day 2, I knew I had a charging system issue. Did all the diagnostics (I am a newb with electrics), and knew the R/R was toast. Using Posplayr’s recommendation, ordered a Compufire 55402 from Dennis Kirk (fast and free shipping, no tax!).

My engineer neighbor helped (I also ordered the male weatherpack connector as recommended by others). All three stator wires went into the weatherpak connector, with the A-B-C order connected to the G/W-W/Blue-Yellow, respectively, as recommended on someone’s install (I have the two extra wires from the stator; just used 3M88 tape to cover them; also connected the g/w and r/w wires together that ran to the non-existent headlight switch). Connected the negative directly to the battery. Connected the positive directly to the positive terminal on the battery, with an inline 20amp fuse. Mounted the unit, with the left side hole utilizing the right bolt of the fuse box. Used a 1/4” drill bit to drill a new hole for the right side hole of the unit. The right lower corner of the Compufire unit is touching the frame. It just fit! (See attached picture; disregard the stator wires you see in the pic...they are definitely tucked behind the metal plate now).

When I cranked it, it immediately fired up, and when I could see that my headlight wasn’t dimming when the tach went over 2K, I almost started to cry! Put the multimeter on the battery terminals and was getting well over 14V at 4K+. So excited and relieved! I swear the engine was running/idling smoother and seemed more responsive at lower rpms on a test drive. So happy now. Thanks for everyone’s posts, instructions, and help! (I then fixed a leaking front master cylinder reservoir that the PO had superglued; part for my ‘80 1100L was incorrect; finally found a ‘78 part with a flat bottom that worked; no leaks now)!

Life is good!

42FB8B93-8CA7-4B42-817A-E337BF5B8542.jpg

[tom203]

Hooray, good job!

"positive directly to the positive terminal on the battery, with an inline 20amp fuse."

personally, I would use a 25 amp fuse here ,to give me a little margin. Let's see what posplayr says.

[Steedracer]

Sure. I thought I read 20A was the way to go, but I can easily swap to a 25 or 30.

Since my charging system was wonky, could it have impacted the one of the coils (perhaps the one driving cylinders 1& 2, left side as your sitting on the bike)? I could swear I hear more exhaust “sound” or percussive air out of the left side now and bike seems more peppy now, especially at lower rpms? Just curious.

[posplayr]

Hooray, good job!

"positive directly to the positive terminal on the battery, with an inline 20amp fuse."

personally, I would use a 25 amp fuse here ,to give me a little margin. Let's see what posplayr says.

I would never directly connect the R/R(+) to the battery. Doing this is what requires 20-25 amp fuses. A proper connection to the "T" would result in only needing a 15 amps fuse.
The 20-25 amp fuses will allow much more current to flow through the wires that can only handle 15 amps safely.

Explained here.

https://www.thegsresources.com/_forum/showthread.php?152769-GS-Charging-System-Health&p=1138898#post1138898

[Steedracer]

Thanks fo the link Posplayr. I’ve not seen that table before (contrasting the two methods) and wish I would’ve. I had re-read Nessism’s Top Ten Newbie mistakes again (and other printed out posts I had saved) and followed the recommendation to connect it directly to the positive battery terminal with the inline 20A. I assume that I will be okay, unless the fuse blows of course, which will cause th engine to stop running. Other than that I should be good right? She sure is charging great now!

[posplayr]

Thanks fo the link Posplayr. I’ve not seen that table before (contracting the two methods) and wish I would’ve. I had re-read Nessism’s Top Ten Newbie mistakes again (and other printed out posts I had saved) and followed the recommendation to connect it directly to the positive battery terminal with the inline 20A. I assume that I will be okay, unless the fuse blows of course, which will cause th engine to stop running. Other than that I should be good right? She sure is charging great now!

If your R/R were to short then you would have to pull 20-25 amps through the wires between R/R and battery (depending upon the fuse) till the fuse does blow. If the wires are really heavy (e.g #12) then It is probably OK. You will just have to see if 20 blows or you need 25 amps in this configuration.

[posplayr]

Thanks fo the link Posplayr. I’ve not seen that table before (contracting the two methods) and wish I would’ve. I had re-read Nessism’s Top Ten Newbie mistakes again (and other printed out posts I had saved) and followed the recommendation to connect it directly to the positive battery terminal with the inline 20A. I assume that I will be okay, unless the fuse blows of course, which will cause th engine to stop running. Other than that I should be good right? She sure is charging great now!

There are a lot of people that just simply don't believe what I tell them. What are you going to do?

I guess they assume that I just invent stuff? Little do they realize that I have developed a mathematical model of the situation and have already considered all options (try to at least) before forming an opinion. Obviously, many people are apt to form opinions much less deliberately.

[Nessism]

Never heard of a SH775 shorting to ground. Low risk.

[Steedracer]

Posplayr, your posts and instructional links are amazing. Woud’ve never been able to perform the many diagnoses and repair without them! Many thanks for your efforts and time.

[alke46]

Sure. I thought I read 20A was the way to go, but I can easily swap to a 25 or 30.

Since my charging system was wonky, could it have impacted the one of the coils (perhaps the one driving cylinders 1& 2, left side as your sitting on the bike)? I could swear I hear more exhaust “sound” or percussive air out of the left side now and bike seems more peppy now, especially at lower rpms? Just curious.

You should know that one coil fires cylinders 1&4 while the other coil fires cylinders 2&3.

[Steedracer]

Thanks, alke46. Good to know. Sunny day here today. Plan to take her out this afternoon.