As I carefully and thoughtfully move along through this project, things continue to unearth themselves. Fortunately I've conquered most on my own, but I ran across one today that has me baffled.
Oil system successfully primed today, time for charging the new battery. Wait....new battery. When I got the bike, I looked up the battery the B25 is supposed to take. Series 9, 12V. Ordered it and have had it on the shelf. Then I remembered the guy I bought the bike from gave me a battery for it. 6V. I figured he was wanting to dump an old battery. No big deal. It came with a bunch of other extra parts he gave me.
So as I was fine-tooth combing today, this jumped out at me. What's that sticker on the coil? 6V!? What!? B25's are 12V! Did this guy have the bike running a decade ago on a 6V battery? Really? The bike has a Boyer EI installed. I can't imagine it's a 6V EI????
I'm stumped...... I already found a 12V coil to order but I thought I'd bounce this mystery off of you fine folks first. My bike is an early 1967. That make a difference???
The ignition coils are designed for a primary current of about 4A. This means the 12V coils have a primary resistance of about 3 Ohms while the 6V coils have a primary resistance of about 1.5 Ohms. They can't be mixed!
It's difficult to say for certain but it's possible B25's up to engine number 2050 were 6V. You definitely need to check which B-B electronic ignition system is fitted - hopefully, its the proper 12V system which should be indicated on the ignition module. I would also check that you have the Zener diode fitted.
Quote from: Spaceman on 17 Feb, 2023, 06:33
The ignition coils are designed for a primary current of about 4A. This means the 12V coils have a primary resistance of about 3 Ohms while the 6V coils have a primary resistance of about 1.5 Ohms. They can't be mixed!
It's difficult to say for certain but it's possible B25's up to engine number 2050 were 6V. You definitely need to check which B-B electronic ignition system is fitted - hopefully, its the proper 12V system which should be indicated on the ignition module. I would also check that you have the Zener diode fitted.
I'll be checking the module later today. The installer did a nice job installing it and zip tied the module up inside the neck. Tried to read it with a mirror yesterday but it's tight in there. I'm also going to pull some bulbs and check the voltage ratings.
It has a Zener diode. I went over every connection in the harness, cleaned and lubed them. I also disassembled the Zener diode and heat sink and gave it, and its mating surfaces, the same treatment.
One of the reasons I posted this question on here is I first researched the web, and found a bunch of conflicting information regarding swapping 6V and 12V coils. Many say there's no problem, many say don't do it. My feeling is I'd rather have all the correct and matching items, regardless. Lucas has a famous reputation I'd rather try to avoid. ;D
It's a no brainer with the coil - if you use a 6V coil in a 12V motorcycle, instead of drawing 4 A, it will draw 8 A and will dissipate 50 W more than it was designed for. You'll get a juicy fat spark but it will probably burn away the spark plug electrode at twice the normal rate.
I think it will probably all come down to which B-B ignition module is fitted - if 6V then it's likely the electrical system is 6 V. As well as checking the bulbs, it would also be worth check the horn and the Zener diode to make sure they are designed for the correct voltage.
Got into the module. It's 12V. The bulbs are correct also. Check out the date on the module. It was obviously installed after the bike was pulled out of its storage container.
Although it indicates that it was designed for a BSA/Triumph twin rather than a single, I believe the ignition module is the same for both. Where there may have been confusion in the mind of the person who installed it is that, in the twin configuration, 6 V coils must be used and he may have thought you also needed a 6 V coil when used on a single. The reason why 2 x 6 V coils are needed on the twin is that they are used in series and have the same total primary resistance as a single 12 V coil which is what each 12 V ignition module needs to see.
Good point on the twin vs single application. I'll need to research this particular unit more.
Having spent last week looking into electronic ignition systems and playing around with a B-B Mk IV designed for BSA/Triumph singles, it was very hard to find information on the differences between the B-B ignition modules. My single B-B ignition module is marked Box 00022 whereas your twin module is marked Box 0023. I believe the modules themselves are exactly the same and the only differences between the two Box numbers is the design of the labels!
From the evidence, it looks as though the previous owner ran the twin B-B ignition module with a 6 V coil. Normally, doing this with a conventional ignition set up would double the current going to the coil but, hopefully in this case, this did not cause any damage or overheating of your ignition module. The proof will be in the pudding and whether the module still generates a spark. In principle, if you power up the module and then short and open circuit the two trigger wires going to it at about 1 Hz, it should generate some sparks at the plug.
Ive just taken a quick look at the BB websisite for Box 22
it is clearly 12v and all wiring relates to 12v in the instructions
http://www.boyerbransden.com/instructions.html
so - you will need a 12v coil for sure
actually they are very helpful when I have rung them in the past - I have extracted this from the fitting sheet
1) This unit can run positive or negative earth as long as the ignition coil is fed from
the positive supply.
2) The working voltage is 10 to 16 volts.
3) The ignition coil used should be a 12 volt type with a primary winding resistance
(low tension winding) of more than 3.5 Ohms.
4) The maximum ignition coil current through the unit must not exceed 5 amps.
KIT00048 (BOX00023) Micro MKIV Ignition system for 12v V-Twin (Adapt To Fit, Requires Some Engineering)
KIT00051 (BOX00022) Micro MKIV/MKIII Ignition System for unit construction single cylinder 4-stroke Triumph / BSA engines with 12 volt electrics and side points.
Thank you guys! Great information! This helps settle my brain on the issue. I'll install the 12V I have coming in. Thanks again!
Well folks, here's an update and I've had some great success...and some oddities, of course.
First, once I got the rocker box put back together and the carb, etc. mounted, I primed the motor. I used clear tubing to the head to make sure it was getting oil. It seemed like it was pumping some, even just kicking it.
I went over the electrical one more time before installing the new battery. It all looked good. I installed the battery.....no spark. Dang. Hopefully nothing was wrong with the Boyer unit. The next day, I went over everything around the ignition circuit. The only thing I changed (besides cleaning and greasing every connection) was swapping out the 6V coil for a 12V, previously discussed. I swapped the 6V back in and VIOLA! A nice strong spark. Go figure.....
The next morning, I put the new metal tank on the bike (that needs correct paint), with new petcocks and fuel line. I was determined to get it fired. After all, this was a motor I've never heard run and was told "she's a good little runner". We'll see.........
I went through the Unit Single starting procedure I've memorized from online. Four kick, she fired right up. No major noises, clunks, bangs or ticks. Not even the expected cloud of smoke. Really? :o I got her warmed up and tweeked the carb a little. After a good warm-up, after well over a decade of not running, I shut her down. Best part? All the lights work.
The next morning I was out to the shop bright and early. To my amazement, it fired first kick. After a nice warm up, I dawned my helmet and rolled it out for its Maiden Voyage up and down the street. Pulling in the clutch, I dropped it into first gear...and it slid right in. To my amazement, releasing the clutch had a nice, predictable friction zone and away I went. Boy, this thing it geared tall.
I'm happy to report that the transmission and clutch work very well. They work as they should. I buzzed it up and down the street a number of times, going through the gears and got it good and hot. The new Amal it came with has settled in after resetting the needle clip. Small stagger is gone. The pilot is WAY rich though. It idles and runs best at 1/4 turn on the mixture screw. This is not the original carb. It was new and supplied by the seller. Set up for a B44 maybe?
Anyway, I currently couldn't be happier with how things are turning out. Thanks for the input everyone. Much appreciated. Also, as pictured, this was after riding it around for a while, then parking it....and then coming out an hour or two later to close up the shop. I was shocked to see, so far, it's oil tight. I was really expecting at least a drop or two. Give it time, right? ;D
Hi As you have an early 1967 model I think you have a C25 "Barracuda". I believe that when it came from the factory it was fitted with a 115W 12V Alternator, ZD.715 Zener, M.A.12 Coil. No need to "die in a ditch" about sticking to originality, unless your driven down that route. I too have a '67 C25 Barracuda, numbers matching, picked it up as a Rat Bike 30 years ago. It's got the lovely GRP tank, that I think I'm going to have to replace, because of the proportion of alcohol in unleaded fuels. Any one with a view on this topic? Also after a centre stand, if anyone can help with that it would be great!
Quote from: SIMON.D.PORTER on 28 Apr, 2023, 14:47
Hi As you have an early 1967 model I think you have a C25 "Barracuda". I believe that when it came from the factory it was fitted with a 115W 12V Alternator, ZD.715 Zener, M.A.12 Coil. No need to "die in a ditch" about sticking to originality, unless your driven down that route. I too have a '67 C25 Barracuda, numbers matching, picked it up as a Rat Bike 30 years ago. It's got the lovely GRP tank, that I think I'm going to have to replace, because of the proportion of alcohol in unleaded fuels. Any one with a view on this topic? Also after a centre stand, if anyone can help with that it would be great!
So sorry for the late response, S.D.P.! I'm not worried about absolute factory perfection. The bike is a nice specimen but not Concours, by any stretch.
From what I understand, no Barracuda's were imported to the US due to Plymouth owning the name, so the early US models were still called Starfire's. Please correct me if I'm misunderstood on this factoid.
Regarding the metal tank, I painted it with the factory color paint by RS paints after a good prep and priming. Their rattle cans worked very well. Of course, my side covers are still original and are aged, so the match isn't perfect...yet. Maybe ten years or so? ;-) Anyway, I'm leaving them as-is. The only complaint I have with the metal tank is wow...it buzzes. I even lined the frame with a sliced pool noodle for thick insulation for it to sit on. I'll have to take it back off and look to see where it may be touching or why it's buzzing. Maybe I have the mounting nut too tight?
I did locate the 1967 sticker set for it and applied a few of them, but I didn't want to go crazy. The gold tank badges came with the bike. The red plastic badges it came with are smaller teardrop, and cracked, so I stuck with the larger gold ones that the metal tank required. Attaching them was a chore, as the holes in the metal tank were too small for the stock screws. I did have some beads of sweat rolling off my forehead when I was enlarging them.
The bike came with a pair of tanks, both fiberglass. One is the small one, one is larger. I guess they offered two?...or one was for the US, maybe? Anyone with knowledge on this, please chime in.