Thinking about a dual sport/adventure Motorcycle

[Ted]

Swapped the 37/11 (3.36:1) final drive onto the BMW today. I’ll need to ride it more to see what I think, but initial impressions are that it does what I wanted it to.

 

[Ted]

I've gotten to put some miles on the 1150 since doing the weight reduction and the final drive swap. The bike is heavily transformed now, and I'm really enjoying the changes.

First off, weight reduction. Previously I'd removed around 20ish lbs between the lightweight muffler, removing the center stand, and some brackets that are unused. However, all of that is low weight. It reduced the overall weight of the motorcycle which is still going to help with physics. The next weight reduction of the ABS delete and lithium battery made even more of a difference. The ABS module and the battery are about as high as the CG can get on the bike, right underneath the gas tank and slightly in front of where I sit. That makes a much bigger difference since that will lower the weight and also lower the CG. To complete the ABS delete, I also removed the trigger rings off of the wheels, which were surprisingly heavy at over 1 lb each, and that's unsprung and rotating mass, although not enough that it would be noticeable by itself.

The weight reduction has the expected effect. The bike feels much lighter and is easier to maneuver in all aspects, whether it's pushing it around the shop, getting it off the stand, or leaning it in turns. The bike is now down around 40-50 lbs from when I first started caring for it, and that is really significant.

Then the final drive. BMW offers a number of different transmission and final drive gearings with boxer engines from this generation, and the 1150 is in a good spot in that there are a lot of compatible options. The R1150GS of this year range had the transmission with the tallest gears, and then the tallest final drive. If you're looking to put a lot of highway miles on the bike, this isn't a bad combination. It's still not bad from a start, and only spins around 3500 @ 70 in stock form, which is really pretty decent (and lower than the current R1250GS). But your torque multiplication is less and for how I use the bike, there's a lot of clutch slipping at lower speeds, and just makes the thing feel more lazy and uninspired (as @Bill put it).

The 37/11 (3.36:1) final drive from an R850R means that in any gear for any speed you're revving about 20% higher and have that 20% extra torque multiplication. At low speeds, this is really noticeable. There's no clutch slippage for most of my technical riding now, no revving at all required when letting out the clutch from a stop, and that extra torque multiplication and revs make the engine feel a lot zippier and more inspired. The bike feels much faster and sportier (because it is), and the extra revs really aren't bothersome. It does make it less desirable for an iron butt, but it's still revving pretty similarly to a new R1250GS and not at all to a level that's bothersome. The muffler is still keeping the exhaust quiet enough in cruise that it's not droning or annoying.

So, these upgrades have done exactly what I wanted and the bike is pretty well transformed from its more lazy initial configuration it was in when I started riding it last summer.

I still have the high compression cylinders, which I do want to install, I'll just have to figure out exact timing of when I do that. Probably not immediately since we're coming up on riding season.

 

[Ted]

I'm getting to where I want to start getting parts in to do the 12V conversion on the Morini.

The Morini has what I consider to be a fairly unusual alternator that has three voltage outputs. An AC circuit that goes to power the ignition coils, a 12VDC (no-battery) circuit that powers the headlights, and then a 6VDC (with battery) circuit that powers the turn signals, horn, tail/brake lights, and indicator bulbs in the dash. And that's really all there is to the motorcycle, even the tach and speedo are mechanical. The alternator is supposedly good for 100W, which makes sense since this is a kick-start only. The headlight is the only real power consumer. So overall, very low power production and very low power requirement. Since the headlight is 12V and has no battery, it only comes on when the engine is running.

Someone typed up instructions that show how to rewind the alternator, for those interested, you can see here:

https://www.motomoriniclub.nl/6-Volt-conversion.pdf

The thing is, you're supposed to figure out your own voltage regulator. In this setup as I understand it, essentially you create a single phase alternator that then needs to feed the regulator. So I suppose I need to figure out a regulator that will work, as there are remarkably few recommendations out there, and it seems a lot are 3 phase (although some say if you're using for a single phase you can just ignore one of the yellow wires). Once I get that figured out, I think the rest of it is essentially straightforward.

 

[charheep]

I am enjoying reading these.

 

[Bill]

Simple bridge rectifier?


https://www.electronics-tutorials.ws/diode/diode_6.html

 

[Ted]

Simple bridge rectifier?

https://www.electronics-tutorials.ws/diode/diode_6.html

I think more or less, but it still needs to also be a regulator to maintain 12V.

 

[mondtster]

The thing is, you're supposed to figure out your own voltage regulator. In this setup as I understand it, essentially you create a single phase alternator that then needs to feed the regulator. So I suppose I need to figure out a regulator that will work, as there are remarkably few recommendations out there, and it seems a lot are 3 phase (although some say if you're using for a single phase you can just ignore one of the yellow wires). Once I get that figured out, I think the rest of it is essentially straightforward.

Single phase regulator/rectifiers are quite common for older machines. There are plenty of options available, you'll just have to figure out what one fits the application best. Here's an example.

http://www.mapcycle.com/categories/...-rect-i-regulator-rectifier-ac-to-12v-dc.html

 

[Ted]

Single phase regulator/rectifiers are quite common for older machines. There are plenty of options available, you'll just have to figure out what one fits the application best. Here's an example.

http://www.mapcycle.com/categories/...-rect-i-regulator-rectifier-ac-to-12v-dc.html

That one actually looks like it probably does what I'm looking for, thanks. I'm going to look at the bike a bit more to make sure I have it figured out, but I think that covers it.

 

[Ted]

I rode the Morini around the block last night after work as I wanted to better explore the holes in the fueling and see if I could figure out what was going on with it. The Dellortos don't have an accelerator pump, so the vacuum signal through the venturi becomes very important, especially in throttle transitions. These are PHBH 30 carbs (30mm) which were specific to the American market, and apparently also jetted leaner for US emissions (no surprise). The European markets had PHBH 28 carbs (28mm) which will provide a bit better vacuum signal, especially at lower throttle positions.

While Chinese knock-off carbs are cheap, the genuine articles are not, and my desire to do carburetor work is even lower. So I'll probably just keep thinking about what I want to do with it for a while, and also do the 12V conversion since that will let me update a few things on it. I may just check eBay to see if some 28mm units pop up for a reasonable price to put on it, but really the bike needs the rear brake done more than anything, and just riding it some more.

 

[Oldmanb777]

Just ordered springs and valves for the Africa twin. been wanting to do the suspension for a long time. Just another thing I haven't gotten done. Needs new tires also. So a good time to do both.

 

[szwinger]

I rode the Morini around the block last night after work as I wanted to better explore the holes in the fueling and see if I could figure out what was going on with it. The Dellortos don't have an accelerator pump, so the vacuum signal through the venturi becomes very important, especially in throttle transitions. These are PHBH 30 carbs (30mm) which were specific to the American market, and apparently also jetted leaner for US emissions (no surprise). The European markets had PHBH 28 carbs (28mm) which will provide a bit better vacuum signal, especially at lower throttle positions.

While Chinese knock-off carbs are cheap, the genuine articles are not, and my desire to do carburetor work is even lower. So I'll probably just keep thinking about what I want to do with it for a while, and also do the 12V conversion since that will let me update a few things on it. I may just check eBay to see if some 28mm units pop up for a reasonable price to put on it, but really the bike needs the rear brake done more than anything, and just riding it some more.

I hesitate to respond as it will likely not come across in the spirit I intend. I like following along with your adventures. I like all sorts of motorcycles. I raced a Monarch 125. You have a Moto Morini. Very few people can say that. Yours runs. Even fewer can say that. No disrespect intended. Why don't you just ride it? Adapt to its quirks.

I get trying to make things better. It's a Moto Morini. It runs. Enjoy it.

I'll go back to lurking now.

 

[TCABM]

…So I'll probably just keep thinking about what I want to do with it for a while, and also do the 12V conversion since that will let me update a few things on it…

Megasquirt to the rescue

 

[Ted]

I hesitate to respond as it will likely not come across in the spirit I intend. I like following along with your adventures. I like all sorts of motorcycles. I raced a Monarch 125. You have a Moto Morini. Very few people can say that. Yours runs. Even fewer can say that. No disrespect intended. Why don't you just ride it? Adapt to its quirks.

I get trying to make things better. It's a Moto Morini. It runs. Enjoy it.

I'll go back to lurking now.

Your post is certainly taken in the spirit is intended and your perspective is absolutely valid. To be clear, I am riding it and enjoying riding it when I do. I am learning to adapt some to its quirks (the fairly narrow steering angle being the big one). It is perfectly rideable as-is, although adding the rear brake is something that is a semi-safety issue as well as just making it work how it should.

The way my brain works, I'm always looking for tinkering and making things work better and experiment to learn something new. There are still some reasonable holes in this, and I'm wanting to enjoy it for what it is. The BMW I have the way I want it now, for example (ok fine I do still want to do those high compression pistons on it).

But yes, taken in spirit.

Megasquirt to the rescue

While I have thought about that, I don't think I want to do that on this bike. I could get a couple of throttle bodies from an EFI boxer BMW and those would be not too difficult to adapt. Adding an external fuel pump wouldn't be bad, and the way the fuel tank is set up it could be set up with a supply and return. But aside from adding weight, I think I'll stick to carbs on this bike.

 

[TCABM]

…
While I have thought about that...

I was only half joking…TBI/FI is probably more effort than it’s worth.

Curious how your tail/stop light gets power. I would expect it to be on the same 12v circuit as the headlight.

 

[Ted]

Curious how your tail/stop light gets power. I would expect it to be on the same 12v circuit as the headlight.

Nope, the tail/stop light and turn signals are 6V. I'm going to get rid of the 6V system and just put all of the lights on 12V, which will require getting a 12V bulb for the back. I'm putting different turn signals on that don't stick out so much. This ultimately helps to protect the bike since the stick-out signals are prone to damage when dropped. And, well, it is a dirt bike.

 

[charheep]

Maybe this will help?

 

[Ted]

Maybe this will help?

It would definitely change my ability to say I have a Moto Morini that runs...

 

[TCABM]

Nope, the tail/stop light and turn signals are 6V. I'm going to get rid of the 6V system and just put all of the lights on 12V, which will require getting a 12V bulb for the back. I'm putting different turn signals on that don't stick out so much. This ultimately helps to protect the bike since the stick-out signals are prone to damage when dropped. And, well, it is a dirt bike.

So very….Italian. When I converted an old XR250 to street legal, I used flush mount signals on the rear fender and mini-stalks up front for the same reasons.

Tusk has a setup that would allow you to bypass the bike electric completely.

https://www.rockymountainatvmc.com/...ro-lighting-kit-with-handguard-turn-signals-p

 

[Ted]

Tusk has a setup that would allow you to bypass the bike electric completely.

https://www.rockymountainatvmc.com/...ro-lighting-kit-with-handguard-turn-signals-p

I think my solution will be a lot less expensive.

 

[Ted]

While perusing eBay I found a few Dellorto PHBH 28s in need of rebuild and managed to win those auctions cheap enough that it was worth getting them on the way. We'll see if the things are even rebuildable. Since the Morini runs and rides just fine now I will continue to ride it. Rebuilding these carbs is a pretty quick process with them off the bike, so I could just do that when I have half an hour here or there and swap them on when I have a chance.

 

[Ted]

Just finished the one day BMW factory off road course, one day street survival is tomorrow. Tons of fun, highly recommend. Definitely did things I wouldn’t have expected I could do with this bike and learned a lot.

 

[SoonerAviator]

Just finished the one day BMW factory off road course, one day street survival is tomorrow. Tons of fun, highly recommend. Definitely did things I wouldn’t have expected I could do with this bike and learned a lot.
View attachment 106015

Man, that course must be intense if they teach you to ride inverted.

 

[Bill]

Man, you guys did loops on the first day!

I’m signed up for the two day this fall. How was it?

 

[Ted]

Man, you guys did loops on the first day!

I’m signed up for the two day this fall. How was it?

Which are you signed up for, 2 day on or off road? Then I’ll give a review accordingly.

 

[Bill]

Two day off-road, renting their 1200 GS.

 

[Ted]

1250 you mean

The off road course is really incredible. The training is great. I definitely learned some techniques I didn’t know and also was able to push things harder than I’ve done myself.

The trail rides break your brain. I knew the bike could do incredible things off road. What I didn’t realize was how effortlessly I could do them with that bike at my skill level. I consider myself maybe a bit above average of a motorcycle rider at best on road, and a novice off road. We were riding single tracks through the forests on the BMW property with big climbs, drop offs, turns in mud up a hill, pushing the thing through stuff I see pros on YouTube do, and here I am doing it too. Maybe not as gracefully, but I’m still doing it and not dropping the thing in there.

The on road was fantastic too. But the big difference was that I knew I could do all the on road things, it was just getting better and good high performance practice. The off road taught me I could do things I didn’t think I could.

Oh, and make sure to get the plant tour. It’s really neat to see the factory.

 

[Oldmanb777]

I was just out in the garage to get a step ladder. Noticed a puddle under the left fork on the AT. Those new fork seals can't arrive soon enough.
I have a riding buddy who has never done much dirt. He is a Motorcycle safety instructor, and double iron butt, but never much if any dirt. I maintain, if you never rode dirt, you never learned to ride!!!!! Anyway he has a new KLR. So we have been out doing some mild dirt stuff. He wants to take an offroad course. I think i will join too. I'm sure I could learn a lot and freshen up some skills i have forgotten.

 

[Ted]

Sticking with the goal of keeping the BMW work cheap, I ordered some Amazon Chineseium adventure pegs:

After doing the BMW off-road class, I was convinced that I really did want adventure pegs on the bike. I also didn't want to spend much money. These were $26 vs. $100+ for some name brand ones. Yes, definitely cheap, but they also do the job just fine. I was happy with them on the ride to work today.

Separately, I got a three Dellorto PHBH 28s for the Morini (two of which are actually usable). My plan is to rebuild those and throw them on the bike, and try to get the jets right for it. These 28s are actually slightly easier to make jet changes to vs. the 30s on the bike, so I'm thinking my best option is probably to get some jet kits, some rebuild kits, throw them on with a best guess and see what I can do with those. That's just fun to tinker with when I have a few minutes here and there between rides.

 

[Ted]

I decided to go ahead and do the 12V conversion on the Morini. this is really pretty simple since all it involves is a new battery, a new rectifier, some new bulbs, and minor rewiring. Since the battery is tiny and doesn't have to start the thing I found a small $15 one off of Amazon and put that on. I got the rectifier that @mondtster had sent a link to. It looks to be a good unit and should work well, although their wiring diagram shows the red wire going to ground, and the black/brown wire going to positive/battery. They also say that it can be used for positive or negative ground, and given how that is different from the normal color convention of red to positive and black to negative, I've asked them the question about whether that is for positive ground, negative ground, or it doesn't matter (pretty sure it would matter).

Doing the conversion requires some minor modifications to he stator on the generator, which I did. Basically you have to cut a couple wires and solder in a couple of different wires. Nothing particularly complex. In thinking about it, I think that you could technically get away with not modifying the stator, but that would remove some of the benefit of the conversion since one of the benefits is you can run the headlight off the battery.

My carburetor rebuild kits showed up for it today, so when I have a bit of time I'll pull the tank off the Morini, pull the 30mm carbs that are on there, remove the parts I need from them for the 28mm carbs and throw them together and on. I'd ideally wanted to put the 28mm carbs together, but after looking in the various Morini information sources that I could find, there was essentially no consensus on what I should use for the 28mm carbs. It seems that these Dellortos are very sensitive to tune based on what may have been done to the engine. The one thing that everyone agrees on (including Dellorto) is that putting the same jets and needles in a smaller carb should tend to make it run richer. So, I'm just going to start off with swapping what's in the current carbs and see what results that produces. From there it's easy to drop the bowls and swap out jets. The needles are a bit harder as they require pulling the tank, but still not awful.

I rode the BMW to work this week when I went in. After doing some searching, I was able to find how the Ohlins rear is supposed to adjust. This bike has an Ohlins rear shock that I could find no references to directly, but I was able to find a video for another Ohlins that showed how they're supposed to be adjusted. I'd played with the adjustment some before, but it turns out completely wrong. So now I'm making more adjustments, and it definitely seems to be helping. I can say it doesn't seem like it needs a rebuild done to it, just some more adjustments.

I also have had some conversations with the copper head gasket maker who I'd talked to some before, and decided to order a set of copper head gaskets for the high compression piston swap. That'll be another sort of project I'll do when I have a full day (and also something I won't do until I have the Morini starting easier and running well). But I do feel that I'm getting the bike dialed in well for what I want and am enjoying it.

 

[Oldmanb777]

Just did the springs and valves on the Africa Twin. Cogent supplied the springs and valves. Race Tech supplied the bushings and seals. Left fork looked new, even though it was leaking. Right fork looked like a blemished "friday afternoon blemished b grade part". I couldn't see any reason for the blemishes and such, and can;t see that it will compromise the future. Just cosmetic, but still. Anyway, its done. So now to adjust the preloads and dampening. Seems much better than stock already. Predictable and planted, not vague.
Also replace the tires and tubes. New EO-7's. nice tires, a bit aggressive for my use, but I liked them before. Also some new brake pads for the rear. Not too long and I will need the first valve check, that should be fun.

 

[mondtster]

I decided to go ahead and do the 12V conversion on the Morini. this is really pretty simple since all it involves is a new battery, a new rectifier, some new bulbs, and minor rewiring. Since the battery is tiny and doesn't have to start the thing I found a small $15 one off of Amazon and put that on. I got the rectifier that @mondtster had sent a link to. It looks to be a good unit and should work well, although their wiring diagram shows the red wire going to ground, and the black/brown wire going to positive/battery. They also say that it can be used for positive or negative ground, and given how that is different from the normal color convention of red to positive and black to negative, I've asked them the question about whether that is for positive ground, negative ground, or it doesn't matter (pretty sure it would matter).

Many of the old British motorcycles were positive ground. The drawing you’re looking at likely reflects this. The nice thing is that the case of the regulator is isolated so you could use it on either a positive or negative ground system. If in doubt, I would just start the motorcycle with the red and black wires disconnected and use a volt meter to verify the polarity of the output before connecting it to the battery. I think it is reasonably certain that the wiring polarity/colors are the way everyone would assume they are.

 

[Ted]

Many of the old British motorcycles were positive ground. The drawing you’re looking at likely reflects this. The nice thing is that the case of the regulator is isolated so you could use it on either a positive or negative ground system. If in doubt, I would just start the motorcycle with the red and black wires disconnected and use a volt meter to verify the polarity of the output before connecting it to the battery. I think it is reasonably certain that the wiring polarity/colors are the way everyone would assume they are.

That was my thought as well. Next time I work on it I’ll try that.

 

[Ted]

As usual, I'm continuing to think about tweaks that I could do that might improve things on my various machines. Here's one for the electrical engineers in the house.

As I've mentioned before, the BMW has had an engine swap. This is an earlier R1150GS which originally came with a single spark engine. However the engine has been swapped with a later twin spark engine (two spark plugs per cylinder).

BMW did this originally to help with some issues with lean surges/misfires that some people reported on their motorcycles. The ECU tuning from the factory on this is pretty lean for an older air-cooled cylinder design to meet EPA/emissions requirements, and so while that helps fuel economy, it's known to be sub-ideal for horsepower and general engine running. I've improved this by making it run a bit richer, but having both spark plugs firing would probably also help running.

Since this bike doesn't have the wiring harness (or I believe the ECU) to support this, the question is figuring out how to do it on my own. If I wanted to go all out (I don't) I could put on a MegaSquirt with Ford EDIS-4 setup and have that replace both ignition coils. It would work pretty well, but I don't think I want to do that route.

The factory setup is a single wasted spark coil - +12V delivered to one side and then the ground side is interrupted to fire the coil. This is a pretty normal/standard sort of setup. I am thinking that what I'd like to do is get a second coil that I can provide its own +12V power source to with a relay connected to ignition, but then I would have to figure out the firing aspect. Essentially, what this requires is creating a circuit that interrupts the ground for the secondary ignition coil at the same time that the ground is interrupted for the primary ignition coil.

I'm thinking that I should be able to wire in a transistor of some sort that is normally closed and then opens when triggered by the ground getting interrupted from the primary coil. However, I'm not used to EE circuitry design (read: I don't know anything about it, I'm a mechanical engineer and I can't solve this with a hammer) so off the top of my head I'm not sure what I should be looking for. This will have some current associated with it since it's an ignition coil, which probably impacts things.

Any of the EEs on here have some thoughts of what I should be looking for, or if there would be too much of a time delay in activation for this to work as desired?

 

[mondtster]

As usual, I'm continuing to think about tweaks that I could do that might improve things on my various machines. Here's one for the electrical engineers in the house.

As I've mentioned before, the BMW has had an engine swap. This is an earlier R1150GS which originally came with a single spark engine. However the engine has been swapped with a later twin spark engine (two spark plugs per cylinder).

BMW did this originally to help with some issues with lean surges/misfires that some people reported on their motorcycles. The ECU tuning from the factory on this is pretty lean for an older air-cooled cylinder design to meet EPA/emissions requirements, and so while that helps fuel economy, it's known to be sub-ideal for horsepower and general engine running. I've improved this by making it run a bit richer, but having both spark plugs firing would probably also help running.

Since this bike doesn't have the wiring harness (or I believe the ECU) to support this, the question is figuring out how to do it on my own. If I wanted to go all out (I don't) I could put on a MegaSquirt with Ford EDIS-4 setup and have that replace both ignition coils. It would work pretty well, but I don't think I want to do that route.

The factory setup is a single wasted spark coil - +12V delivered to one side and then the ground side is interrupted to fire the coil. This is a pretty normal/standard sort of setup. I am thinking that what I'd like to do is get a second coil that I can provide its own +12V power source to with a relay connected to ignition, but then I would have to figure out the firing aspect. Essentially, what this requires is creating a circuit that interrupts the ground for the secondary ignition coil at the same time that the ground is interrupted for the primary ignition coil.

I'm thinking that I should be able to wire in a transistor of some sort that is normally closed and then opens when triggered by the ground getting interrupted from the primary coil. However, I'm not used to EE circuitry design (read: I don't know anything about it, I'm a mechanical engineer and I can't solve this with a hammer) so off the top of my head I'm not sure what I should be looking for. This will have some current associated with it since it's an ignition coil, which probably impacts things.

Any of the EEs on here have some thoughts of what I should be looking for, or if there would be too much of a time delay in activation for this to work as desired?

You may not need to overthink it. Dual plugging the old Triumphs is common, people just use two dual outlet coils and wire them in series.

Of course, that assumes that the ignition lead is intended to be the same for both spark plugs. Do you know what the ignition lead on the original dual plug setup was at?

 

[SoonerAviator]

Any way to use a coil-on-plug system to send one signal to both coils?

 

[Ted]

You may not need to overthink it. Dual plugging the old Triumphs is common, people just use two dual outlet coils and wire them in series.

Interesting. I hadn't considered that, mostly since that would half the voltage going to the coils which I would think might make them fall off at high RPM. This thing only redlines at around 7500 though, so really not all that high relatively speaking. I'd thought about running in parallel, but was worried that would run too much current through the ECU and potentially fry it. I may be overthinking that, too. At that point, I'd probably be more likely to replace with a Microsquirt as it wouldn't cost much more than a used ECU off eBay and give me a lot more options. And then I'm going way down a rabbit hole, which really I'd rather avoid with this thing (says the guy who's putting high compression pistons and copper head gaskets on because it's fun).

Of course, that assumes that the ignition lead is intended to be the same for both spark plugs. Do you know what the ignition lead on the original dual plug setup was at?

I've done some digging on that. I haven't found anything that indicates the second spark plug was fired at a different time. The only thing I did find was that the second spark plug doesn't fire all the time in factory configuration, but that wasn't necessarily from a credible source. For my purposes, I think it would be reasonable to assume that firing at the same time would be acceptable. For reference, this is what the combustion chamber looks like, and you can see where the two plugs are located:

You can't really tell in the picture, but that second plug is located on the bottom, between the lower intake and exhaust valve.

Any way to use a coil-on-plug system to send one signal to both coils?

That's essentially what I'm trying to figure out, is if there's a way to use the one signal for both coils.

 

[mondtster]

Interesting. I hadn't considered that, mostly since that would half the voltage going to the coils which I would think might make them fall off at high RPM. This thing only redlines at around 7500 though, so really not all that high relatively speaking. I'd thought about running in parallel, but was worried that would run too much current through the ECU and potentially fry it.

https://www.triumphrat.net/threads/wiring-procedure-2-x-6-volt-coils-in-series-on-t140v.790273/

I didn't read the whole thread, just enough to know that some of the highlights are discussed there. Basically, you run two 6v coils in series. It's common to do it that way, even Triumph did it from the factory.

You could potentially run two 12v coils in parallel but there is some risk of damaging the transistor controlling the circuit if the current is too high.

What kind of ignition module does this motorcycle use? Or are the coils directly wired to the ECU?

I've done some digging on that. I haven't found anything that indicates the second spark plug was fired at a different time. The only thing I did find was that the second spark plug doesn't fire all the time in factory configuration, but that wasn't necessarily from a credible source. For my purposes, I think it would be reasonable to assume that firing at the same time would be acceptable. For reference, this is what the combustion chamber looks like, and you can see where the two plugs are located:

You can't really tell in the picture, but that second plug is located on the bottom, between the lower intake and exhaust valve.

The second spark plug placement in that head was rather interesting. What do the single plug heads look like? Do the dual plug heads run the same ignition lead as the single plug ones?

Is there any tuning software to work on the OE ECU?

 

[Ted]

https://www.triumphrat.net/threads/wiring-procedure-2-x-6-volt-coils-in-series-on-t140v.790273/

I didn't read the whole thread, just enough to know that some of the highlights are discussed there. Basically, you run two 6v coils in series. It's common to do it that way, even Triumph did it from the factory.

That all makes sense. So I think the real trick would be finding two 6V coils that I think would work. Doing a bit of searching, it looks as thought this isn't all that hard to find, this seems to have it:

https://www.ebay.com/itm/372221816823

So really, next time I have the tank off and have access to the ignition coil, I need to measure the resistance and confirm that it's a 3 ohm coil as I expect it is. If so, this shouldn't be too difficult.

You could potentially run two 12v coils in parallel but there is some risk of damaging the transistor controlling the circuit if the current is too high.

Exactly my concern.

What kind of ignition module does this motorcycle use? Or are the coils directly wired to the ECU?

As far as I can tell, they're wired directly to the ECU.

The second spark plug placement in that head was rather interesting. What do the single plug heads look like? Do the dual plug heads run the same ignition lead as the single plug ones?

Is there any tuning software to work on the OE ECU?

The single plug heads only have the one plug in the center of the combustion chamber (as is common for a pent combustion chamber design). So for the main ignition wire, it's the same. For the bottom plug they do have a different wire. At least on this bike, it's a standard ignition wire, which since they're connected to nothing are just dangling under the gas tank.

It looks like if I bought those coils I linked above (or something similar) that ought to do the trick. Doing a little more Googling, it seems that this has been used on a lot of airhead BMWs as a mod for some time to help with running.

 

[mondtster]

The single plug heads only have the one plug in the center of the combustion chamber (as is common for a pent combustion chamber design). So for the main ignition wire, it's the same. For the bottom plug they do have a different wire. At least on this bike, it's a standard ignition wire, which since they're connected to nothing are just dangling under the gas tank.

It looks like if I bought those coils I linked above (or something similar) that ought to do the trick. Doing a little more Googling, it seems that this has been used on a lot of airhead BMWs as a mod for some time to help with running.

What I was wondering was if the head design of the single plug was identical to the dual plug heads with the exception of the second plug. It is possible that the dual plug head was an effort to “fix” a drivability problem with the single plug engine that was really a problem generated by emissions compliance efforts. Is it possible that a performance oriented ECU tune would fix all the problems?

Best I recall, the airheads had a head design similar to the old Triumphs and Harleys. The design required a lot of ignition lead which led to a lot of negative work and risk of knock. Dual plugging those motors was a common way to reduce the amount of ignition lead needed so the power would go up and the risk of knock would go down. It seemed to work pretty good.

The head in question and the second plug seems to be an effort to cure a different problem.

Anyway, those Dyna coils should work…

 

[Ted]

In this case, as I understand it it's mostly about driveability problems caused by the lean mixture. The cylinder design is identical between the single and twin spark heads other than the second plug. I've not had any of the driveability issues, but I'm more looking for better performance and responsiveness that would come from better ignition (they also say better mileage). I've richened the mixture up some already and that has helped.

I'll do a bit more digging before buying anything, but I think now I have a viable path that should work and not hurt anything electronically. And that puts me in a good spot.