'82 Moto Guzzi v50 Rebuild/Redesign

I put the following together in response to a question that came in by email in regards to wiring and electronics. I believe that many or most all of you on this forum already know this stuff, but perhaps it will be a helpful comprehensive point of reference for some.

Regarding the electronics, here are some things you need and need to know:

Basic & Essential Information
1. Start by reading this excellent post to get a better understanding of motorcycle wiring and the possible solutions out there: http://www.bikeexif.com/motorcycle-wiring

Guzzi specific: Maybe have a look at this to get a better sense of the wiring sizes, etc. that you will find on a Guzzi: http://www.s3750motoguzzi.co.uk/rewiring/rewiring.html

2. Find a copy of your wiring diagram!

Guzzi specific: Many wiring diagrams available here: http://www.thisoldtractor.com/guzzi007/sportissimo.html I found that the colors may not match up 1-to-1 with a given bike's wiring harness, but the layout of one of these is probably 90+% correct. I attached the wiring diagram that I found best for my bike to this email.

Wiring and Terminals
If you are just going to use the existing wiring harness and switch gear, chance are you will need new terminals. If you are going to make a custom harness, then you will need wire too. These can be sourced from the following places:

Terminals:
http://www.vintageconnections.com/
http://www.cycleterminal.com/flag-terminals.html
ships to Europe only: kojaycat

Wire:
As far as I can tell, in the US it is easiest just to get to your local car parts store. Worse, once there you will have to make sense of the insane AWG system. That is right, here in the US this formula explains the cross sectional surface area relationship between, say, 12 and 14 guage wire:

God help us...

If you are on the metric system, well, it all just make sense (surprise?)

If you are in Europe you are in luck because you can buy an amazing selection of cut to length wire from this company: kojaycat

Why they wont ship to the US when I made it clear that I would pay virtually any shipping price they wanted? I don't know. That is why I tried to avoid giving them an active hyperlink.

Also, if you are going the mUnit route you can just buy one of the wiring kits directly from Motogadget (Non-US ordering) or from one of these two places:
http://revivalcycles.com/collections/for-your-ride-bestsellers/products/revival-cycles-deluxe-cable-kit
https://spieglerusa.com/gauges-instruments/electrics/control-box/m-unit-cable-kit.htm

Crimping Tool
You will also need a crimping tool, these are available from the terminal vendors. This is where I bought mine. I am not in love with it because the axial movement frequently leads to malformed crimps, but it got the job done.

Lithium Ion Batteries
I believe that most of the conventional Lithium motorcycle batteries available are just plastic packages containing multiples of 4 A 123 LifePO4 battery cells, or the same cell by some other manufacture. I don't recall the brands, but I have found one or two high dollar Li batteries that include some special power optimization circuitry integrated into the battery. While these batteries are seem to be 2x the cost of a Ballistic (link to this later) I have no doubt that this does in fact serve to extend the life of the Li cells in the batteries. The cells seem to be pretty fickle about the current that they like to charge off of, and I suspect that the general charging circuit on a motorcycle isn't optimal (I would love to go deeper into this at some point).

So, here are your options if you want an Li battery.

1. Buy one from Ballistic or another manufacturer: https://www.ballisticparts.com/category.php?cPath=141 The batteries will come in various multiples of 4 cells (each cell is 3.2 v, so 4 in series gives you 12.8 v, which gets you above the requisite threshold for running the 12v electrical system).

Small Twin Guzzi Specific: You will probably want an 8 cells, and oh btw, these bikes might actually necessitate that giant stock Bosh starter.

2. Make a Li battery! The A123 cells can be purchased through ebay. Buy some multiple of 4 of these, solder them together into packs of 4 cells in series, and then conjoin these packs somehow. Here are some youtube instructions: --https://www.youtube.com/watch?v=UTDctiyUa9E--

Note on my setup: I elected to use option 2 because it gave me some flexibility on shape. Rather than arranging the cells side by side, I arranged them literally in series. 2 "packs" of four cells wired together with heavy gauge battery cable should effectively give me the equivalent cranking power and power reserves as an 8 cell Ballistic battery.

If you go the Li battery route, you should also get an Li specific charger: http://www.ballisticparts.com/product_info.php?cPath=143&products_id=437

You can charge the batteries with a conventional charger, but I suspect it ruins the cells quickly. In a pinch do it, and don't fret. I observed a ballistic tolerate heavy amounts of such abuse over the course of a year (thanks to predictable CX500 stater issues). The performance of the battery was clearly diminished at the end of this, but it still worked.

The Electrical Components
Your electrical system is also going to be comprised by a number of pieces that look like they harken back to the days of vacuum tubes and other primitive electronics, and well, they do.

Who knows which of these pieces still work, and which ones do not. My understanding is that if they work, they work. No need to fix.

Guzzi Specific: If these parts do not work, you can always source replacement parts form one of these companies:
http://www.mgcycle.com/index.php?main_page=index&cPath=37_161
http://www.stein-dinse.biz/Moto-Guzzi/Electrical-Ignition/Regulator-Rectifier:::1_39_197.html

You could also replace your regulator and rectifier with newer technology and pick up one of these:http://www.ebay.com/itm/81-Moto-Guzzi-V50-MK2-Electrosport-Industries-Regulator-Rectifier-ESR450-/371109355208

Note on my setup: Since I was going to be fabricating mounts around all of these pieces, I wanted to start with components I could trust. Thus I elected to upgrade to a contemporary rectifier. This is now mounted on the bottom side of the "back bone" frame rail that runs under the tank. Given that I have removed the factory air box, it should catch nice airflow in its current position. I also eliminated the remainder of the stock electrical components (flasher relay and some other relay), by installing an mUnit (more on this later). mUinit or no mUnit, you will still require a fuse box, and I elected to keep the stock one for no reason besides the fact that I thought it looked cool.

Switch Gear
Guzzi Specific: The stock switch gear is probably fine. You can use this, or swap in other switch gear that will tolerate running a full electrical load. Swapping in mid 70's honda switch gear or something would allow you to ditch the cheep Guzzi switch gear in exchange for cast aluminum options. This might be of appeal.

Given the way the conventional electronic system & wiring harness is set up, if you want to switch to minimalist-style switch gear and/or reduce the bulky ropes of wire running up to the handle bars, you will have to device a way for the switch gear to no longer be running full electrical load, but rather for it to simply be controlling circuits that are running the full load. If you have a basic foundation in electronics you can probably easily fabricate a solution to this...if you don't, you buy an mUnit.

The mUnit
Enter the mUnit:http://motogadget.com/en/electrics/electronic-control-box-m-unit/m-unit-digit-tastersteuerung-u-sicherung.html

Sources:
http://motogadget.com/de/ (EU ordering only)
https://spieglerusa.com/ (US ordering)
http://revivalcycles.com/ (US ordering)

Is an mUnit a need? No...it is a want...but it is so sexy, and in reality it does make doing a custom electronic setup so pain free that you are going to want to try to justify to yourself that it is a need.

Here is why you might give yourself permission to buy one:

1. It makes designing a custom wiring harness a cinch.
2. If a circuit goes down: (a.) the mUnit will indicate which circuit has the short and (b.) you don't need to replace a fuse.
3. The switch gear is no longer managing full electrical loads. The full loads are managed exclusively in the circuits managed by and running through the mUnit. This means that you can can run filament thin wires up to the switch gear on the bars and use minimalist switch gear like motogadget's exorbitantly expensive m Switch family (http://motogadget.com/en/am-lenker/m-switch-3/m-switch.html)
4. It replaces the relays that were just going to fail on you at some point anyways (so you will get your money back in ~400 years of riding)
5. It does nifty brake light stuff
6. It provides an alarm function

And lastly, you might just be honest with yourself and acknowledge that you are buying it because it is impossibly cool...

Concluding Thoughts
I hope some of you out there find this helpful. I took hours of googling and a number of phone calls to all of this out on my end. Even with this info there will still be problems to solve, but all of the foundational information you need to approach that should be contained here in. Happy wiring!

Oh, and an unfortunate lot of us might benefit from this.

Here's a table for AWG amperage that I feel should help safely determine what wire to use, for low current(<5A) momentary draws a smaller gauge wire should be safe, I wouldn't use smaller than #18, the starter I would use the largest I could fit.

Never seen a one of these charts, but makes total sense. Something that was hopefully good just got a bit better. Thanks for posting the resource J-man.

Re the 18 ga wire comment. You can go smaller on the wires running to the switch gear if you are running an m-unit. Motogadget's rec is ~26 ga (0.1mm^2) or thicker. See page 7 here: http://motogadget.com/media/downloads/manual/munit_v2_manual_en_3.2_k.pdf

But yes, for normal circuitry this makes sense.

Had a chance to spend some time with the project for a first time in a long time. In the period during which we have been apart I have had a chance to give ample thought to what exactly I am going to do with the Guzzi's exhaust.

The center stand on the bike was in rough shape. The/a prior owner had lost the shims that the center stand pivots on and simply inserted a M8 bolt. Without the alignment the shims provided the center stand mounts and stops had become worn out, rounded off, or otherwise badly damaged. I contemplated doing the repair work to return everything to a functional, cosmetically acceptable state, but then just decided to remove it and trim off the brackets from the lower frame rail. I saved the pieces, and if I ever decide to undo this it will not be that much more work than the repair work required. For the moment, though, bye bye center stand (hoping to come up with a track stand solution in lieu of to serve as the upright storage solution).

With the center stand gone I have opened up a good bit of space behind the transmission, and my hope is to wind the exhaust into there tuck in two short mufflers to achieve the desired back pressure, and then have the final outlet tuck out just behind the rider's heels. From a visual standpoint this would leave merely the iconic Guzzi heads protruding out the sides of the bike, and would hopefully add to the vintage-modern mashup that I am targeting in the bikes styling.

Since I still have no paper and pencil or other graphics skills with which I might play with different designs, I resorted to building prototype designs using PVC tubing.

Here is that process:

I began by trying to capture the dimensions of the original header/h-pipe/whatever this is called in the motorcycle world. I actually think the lines of the stock unit are quite attractive.

Stock patter:


This produced a unit with an initial bend radius (external) of 10.5 cm:

I thought this looked pretty swell, but keeping it in close enough to the heads and frame would have meant ditching the finned retainers that hold the header to the head. I am hoping to keep these as keeping the exhaust port/valves as cool as possible has got to be a good thing. This lead me to begin sampling other bend radiuses. Here is a 9.5cm radius composed of more cuts:

Thanks to this trail and error, I realized that I really like the segmented look that the 10.5 cm bend had, which is due to the fewer number of pieces composing the bend. To me the straight-lines doing organic shapes that the 10.5 had really speaks to the cubist/rectilinear motif that these baby guzzi's have. Sure, this will reduce exhaust flow, but isn't a touch of back pressure a good thing?

This lead to further sampling and my scrap bin now includes a 10.5, 10, and a 9.5. By the end of that I was a chop saw-protractor wizard. Here are shots of preparing what I believe will be the last and final design:



And the 9 cm radius "mounted"


Can't wait to find access to a TIG again such that I can convert this design form plastic to stainless!

Here is a hint of what I am envisioning for the outlets:

More work to come on the latter half of the exhaust setup, though.

Has been fun thus far. This is a portion of the project I have been looking forward to for quite some time. I will probably have to go with a smaller diameter pipe than the PVC in use to achieve a desirable exhaust velocity. This is a subject which I know very little about, though. This (since day 1) has been new territory for me.

Very nice mock up. This should add a lot to the look of the bike. I like exhaust work, it's the voice of the machine. You might extend your slash cut tip a bit to avoid cooking your heel? Good job.
Cheers, 50gary

Thanks 50gary.

I will certainly extend the tip as advised. It was a quick pass at that portion. I just wanted to see how the concept looked. Please enough to invest some more time.

Also, anyone know how far away from the frame rails I need to keep the exhaust to avoid paint blistering?

And, if anyone has any pointers on how to think through the exhaust velocity question I am all ears.

Cheers and thanks world.

The pipes can be very close to the frame - though no doubt it depends on the paint. Pipe crossing a frame tube at 90 degrees 1/16". Pipe paralleling surface 1/8". Of course this assumes the assembly is out in the open where it gets fresh air. Inside an enclosure is way different. Look at how close a lot of heat shields are which are actually attached to the pipe and intended not to burn you clothes! The pipe diameter the factory used at the cylinder head is likely to be very near optimum on a bike. There are arguments leaning toward the small end of the scale for flow straightening and also for the larger for less restriction, both have problems at some point. The longer and straighter the section leaving the exhaust port (and how well matched and coaxially aligned it is) and the more gentle the bend after it the better. This is to straighten out the very turbulent gas after it leaves the valve more than anything else which will help the flow. More important though is the distance to the collector (presume you have 2 into 1, or 2 into 2, otherwise it will be the distance to the end of the pipe (or entrance to the muffler)). When the valve cracks open, a high pressure shock wave traveling at the speed of sound travels through the gas in the pipe. When it reaches the end (collector, muffler, open atmosphere) an inverted (and weaker) wave is generated that travels back through the pipe to the valve. If it arrives at just the right time, it will generate negative pressure in the combustion chamber helping to vacuum it out. That time will be determined by how long that section of the pipe is and of course that time and therefore the length of the pipe will only be right for a specific rpm (and harmonics of that rpm). Just like waves in water, they can pass through each other undisturbed (mostly). They also don't care much about how curved or straight the pipe is. The shock wave created by the collector returning back to the valve is what creates so called "scavenging". The actual length of pipe calculation is pretty complex as the wave speed (which will be the speed of sound in the material it is traveling in) is determined by both the gas pressure and the gas temperature, both of which are continuously variable along the length of the pipe and also by the ambient temperature and engine performance at the moment, plus you need a target rpm (or range of rpm) where you want the best power. What works at one rpm invariably compromises another. Happily "rule of thumb" formulas work pretty well and there are now readily available computer programs that will take into account a lot of variables which make the solution easy and should have you some good numbers straight away if you are realistic about how you intend to use the engine. There are guys on here that do this a lot more than I do these days so hopefully someone will recommend something current to work from. Be glad you aren't designing a 2 cycle pipe - way more complex, way more influential on engine performance and a lot more trouble to fabricate!

Great looking work so far - keep the pics coming!

Awesome.

This is indeed as interesting as I had hoped.

Going to do 2 into 2.

Will do some hunting through the forum for previously published exhaust theory.

Hey,

Nice build.
I did a guzzi v65 last year,
In the picture you can see how I changed the stock exhaust.


Gertjan

Gertjan,

Thanks. I hope I get to finish it someday. The combine pressures of finding myself back in school whilst simultaneously becoming a parent has left little time for cafe racers.

I generally like what you did with the build, and you rather successfully performed two modifications that I contemplated for mine:

1. I am amazed how well the bike takes to the inverted fork. They baby guzzi's are such fine boned little bikes that I am surprised the girth of the inverted fork doesn't look too of place (going to keep a conventional fork on mine but upgrade to 35mm stanchions setup).

2. The pseudo-floating read end you created works quite well too. I have been trying to talk myself out of going there, but as soon as one ditches the battery and side panels, the length of that subframe section just looks unnecessarily long. (I may still do this, but if I do I will be sticking to the straight lines found throughout the rest of the bike as opposed the the wheel matching curve you introduced.)

3. These bikes take the scrambler look quite well. I generally like the stock tank, but there is a flat ascending panel on the side of the tank that looks totally out of place when you go for the horizontal lines of a cafe racer. This out of sync detail is annoying the hell out of me, and I am concerned that I am either going to have to ultimately make a tank or go scrambler to be content.

Some other ?'s for you:
Did you move the upper rear shock mounts forward at all?
Battery is under the tank I presume? How many cells and how is that working out for starting?
And where did you rear master go? Is it just hidden against the black of the drive train?

While shorty exhausts can look cool and all, I am a pretty firm believer in the concept that form should follow function, and I am still trying to devise a way to get the look I want while maintaining sufficient pipe length to take advantage of the power/torque boosting effects of the scavenging principles that underline inertia tuning principles.

This post has been a fantastic reference on sort all of that out: http://www.dotheton.com/forum/index.php?topic=39814.60

Crunching the numbers, I believe the calculations call for something like 5 ft of tubing length to have the exhaust optimized for the lower RPM ranges at which I presume these engines prefer to run. Thus, there is a reason why the stock exhaust reaches nearly all of the way to the back edge of the back wheel. I might be making some compromises on my principles here.

Anyways, thanks for sharing. Great food for thought as I fantasize about getting back to it.

Hey.

Some answers for you.

Did you move the upper rear shock mounts forward at all?
no they are pretty much on the stock position, I only lined them up with the frame lines.

Battery is under the tank I presume? How many cells and how is that working out for starting?
No it is under the seat, li-ion battery works great no problems yet.

And where did you rear master go? Is it just hidden against the black of the drive train?
no this one I hid under the tank. made a cable setup running true the frame so it is hidden.

great work, loving all the attention your putting in to every piece

I have been brainstorming creative solutions to my timing/ignition system issues, and an important part of this hinges upon making sense of the advance curve.

The picture below is the a diagram of the factory advance curve from the shop manual. I have to say, to me this diagram raises more questions than it answers, and there is no text shedding providing further insight into the meaning of the diagram. There is just a simple statement stating the the max advance is 35 degrees at 5000-5500 rpm.

Here is what i am pondering:

1. What is the story with the shaded areas with different patterns? Is one portion just the acceptable amount of advance in relation to ideal curve (Black line?) and the other portion just the converse? Basically meaning that anything falling in a shaded area is OK with the black line between the shaded areas being the ideal "curve"?

2. Why the jump from 0 to 13 degrees of advance at 220 RPM? And, why the jump from 13 to 25 degrees of advance at 2000 rpm? I admittedly have some self-educating to do in regards to ignition curves, but of what I understand, curve not step is essential to the principal.

Anyone have a better understanding of what exactly is going on here?

Thanks in advance (ha ha).

Curve diagram:

does it have bosch electronic ignition or originally points?

Neither. It had a Dyna S, but for some reason the pickups on the Dyna are incorrectly spaced (off by about 10 degrees). Additionally, the mechanical advance assembly is basically worn out, and would need to be replaced if I wanted to get any accuracy out of it.

I thought I had previously posted this, but the following is a photo of one of the weights form the advance assembly. Note how the advance springs have basically cut through their attachment point (red arrow).

The pivot point for these lobes (the circular opening in the piece I am holding in the pic) is also heavily worn and too loose to have any accuracy. I think the assembly was run without the required lubrication for years.

Points, Dyans, or whatever I choose with that route would basically require that I replace the old advance with a new assembly, but this really seems like sub-optimal technology at this point. Why invest in that?

With that logic in mind, I am planning to keep the cam-mounted magnetic rotor form the dyna, and to use that as the basis for building a digital ignition. An unnecessary amount of effort? Yes, but I am stuck a 1000+ miles away from the project at most times still. This will give me something to keep my mind occupied, and if I fail I can always return to convention.

dyna s is an aftermarket unit to replace the points. that's why it has an advance mechanism. the other system used on the early bikes is a bosch electronic like a darmah or pantah (if you're familiar with either). two little pick ups and control boxes.

usually (i've not had to do points in a v50 for so long i've forgotten) the guzzi had a system where one set of points was fixed to the advance plate, and the other on another plate bolted to the advance plate that could be adjusted relative to the advance plate. so you could vary the timing between the points. on later big twins you often end up slotting all the holes a huge amount on the second plate to get the timing the same on both. not sure if v50 suffer the same, or if the dyna uses that still. are both dyna pickups on one plate?

just looked in the manual linked below, appear to both be on one plate.

contact ignitech and see if they do a box to run off the dyna pick ups. it'll be a lot less agro if they do, you'll just need to disable/lock the advance mechanism.

the advance chart looks to me like the bosch one from the early v35/50 manual. try this manual - http://www.thisoldtractor.com/mg_manuals/workshop_manual_v35-ii_v50-iii_v35-imola_v50-monza_v35c_v50c_v65_v65sp_en.pdf

That weight you are holding looks like a cheap replacement and not the case hardened original... look at an original and see if if it's zink coated


Sent from my iPhone using DO THE TON

the extra retard below 220 is so the starter can build momentum before it starts firing right near tdc which loads the starter

we still do that on electronic ignitions on high compression motors

Tune-a-fish:

Thanks. It would make sense that this should be case hardened, and I agree, it evidently isn't. Thought it was just Guzzi cutting corners. It didn't occur to me that someone might have put in an aftermarket units for some inexplicable reason.

Cxman:

Much appreciated. That makes perfect sense. Thank you. Any thoughts on the jump at 2k rpm? What the hell is going on there?

the jump is how the electronic units worked. all the ducati ones have been single (kokusan) or two (bosch) stage. usually they change from firing at the trailing edge of the flywheel lump to the leading edge, without much provision for gradual in between.