Lakeland CDI Unit With Microprocessor Controlled Advance

[Triple Jim]

We've finished a CDI unit that's triggered from the Motoplat magnetic pickup "distributor" and provides the advance curve of the Magneti Marelli "low performance" dual points distributor.  I chose that curve for this unit because my Mille GT previously had that distributor on it, but we can program any curve we choose.

The CDI unit is based on one  of our standard products, but also has a microprocessor based delay board that we designed and built.  The board receives trigger signals, in this case from the Motoplat magnetic pickups, delays them the correct amount, and sends corresponding pulses out to the CDI unit.  The magnetic pickups are set so they pulse 50 degrees before TDC, which is more than you'd ever actually want for spark, and the delay board then adjusts the timing for the desired advance curve.  For the low performance dual point distributor, this is 2 degrees at 500 rpm, up to 33 degrees at 3,000 rpm, where it stays for higher speeds.  I followed the curve in Guzziology that Dave Richardson made by measuring a distributor that was in good condition.

I've put about 100 miles on the unit so far, and have been amazed at how poorly my old distributor's advance mechanism must have been working.  As an example, after setting the timing to the above specs, I had to back out my idle speed screws in the carbs, because the idle was around 1,500 rpm.  Low end torque, as when starting from a stop, is definitely improved, and the engine feels snappier in the 2,000-3,000 rpm range.  I'm not claiming the new CDI unit caused this improvement, but rather that having an ignition system that's advancing correctly caused it.

I'm going to leave the new unit on my  Mille full time now.  I really don't know how many Motoplat distributors are still around, and if there are any still in use, but if a member here would like to do some beta testing and is mechanically and electrically competent enough to do the installation, please email me and we can talk about a reduced price in exchange for your help.

Based on the parts and labor required to build one of these, I expect the selling price for various versions will probably be $299.00, and as with my other ignition products, will have a 5 year warranty.  Advantages over other systems include very low current consumption (0.6 to 1.1 amps, depending on rpm) ability to run a 0.040" spark plug gap, and low coil heating.  The system will work fine with almost any decent coils.  I'm running a couple Bosch blue coils made for points systems.  The low current consumption leaves a few amps available for battery charging that previously went into heating the coils.

Here's a photo of the delay board.  The small rectangular component with 20 small leads is the 32 bit microcontroller running at 30 MHz.  This is a 3-channel test unit, although only two are used for a Guzzi engine.




Here is the complete CDI unit installed on my Mille GT:

[ITSec]

Nicely done - that should help some people enjoy their machines more, and keep them on the road more often!

[redrider90]

I'm waiting on MPG report.

[Triple Jim]

Me too, Harvey.       I had half a tank when I put this CDI unit on, but have since filled up to the brim and gone 60 miles.  Another 200 to go before I know much about mileage.

The improvements in running I've noticed are between idle and 3,000 rpm, and most of the gas is burned at 3,000 or more, where the timing is the same as it was with the points distributor, so there really may not be much difference in gas mileage.

[nc43bsa]

The problem I remember with the early 90's electronic distributors was that the 2 cylinders could not be timed within 3 degrees of each other.  Does your unit address this?

BTW, my Mille was converted back to dual points before I got it.

[guzzisteve]

I was going to ask that Q !! Every motoplat I worked on ran rough. Checked a few w/degree wheel and the closest one was 89.5* . Never could get them smooth like a Dyna.

Really nice work though. Nice option for the flat top dizzy!!

[Triple Jim]

I checked my Motoplat "distributor" accurately with a degree wheel, and found the two cylinders were within 1/2 a degree of 270 degrees apart (within 1/4 degree of the 135 degree distributor rotation).  Maybe not all of them are that good.  It's certainly possible in software to correct the error if it's a problem, but I don't currently have provision for a user to do that for an individual distributor.

As far as smooth running, the Motoplat ignition unit had a different advance curve from the dual points distributor, with much less advance early on.  A Dyna system installed in the flyweight and spring distributor should have the same "low performance" curve I programmed into my system, advancing more at low RPM.  This may have been a bigger cause of the Motoplat not running as nicely as the Dyna conversion.

[guzzisteve]

That's petty cool, you would have to know how much it's off before you program the processor?

[Triple Jim]

Yes, for this version that's true, but then you'd be stuck using only that distributor with that CDI unit, so it's not a great situation.  I'm planning a version that's user programmable, primarily for racing applications, so that's a possibility. 

Really though, if a Motoplat distributor were off a degree or two of crankshaft timing, and you split the difference, you'd be within a degree on both cylinders.  That's better than you can get looking through the hole in the bell housing, trying to line up with some crudely painted 1/8 wide timing marks, and then trying to set points to that.

[redrider90]

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Here is the complete CDI unit installed on my Mille GT:

Jim,
Your price comes in considerably lower than this place in the the Netherlands @ $470 for a pair. A single unit from them is $250 for one cyclinder Your single unit does the work of the 2 box motoplat system at a considerable discount @ $300!!! Wow.   And your warranty is 5 years to their 2 years.
http://www.carmo.nl/index.php?main_page=product_info&cPath=493_4686_2025_2071&products_id=687&zenid=f5fsjskjfur88bugf12cpeva92
They make plugin replacements for Motoplat.
They use 2 boxes like Motoplat and call it a TCI. Is there a difference between a TCI and CDI?
Any thoughts about doing this for a points dizzy or does making the pickup unit drive the price too high? I know you have run your Mille with points and a CDI reducing electricity consumption as well as wear and tear on the points. But there are a lot of Tonti dual points dizzies out their. Just curious. Also the V65 ran all Motoplat systems didn't they? 

Is there a difference between a TCI and your CDI?

[Triple Jim]

TCI is "Transistor Controlled Ignition".  12v current to the coils is switched by transistors, rather than with points.  CDI is Capacitor Discharge Ignition.  A capacitor is charged to several hundred volts and then quickly discharged into each coil.  I got into making CDI systems because they were used in the Kawasaki triples, and I started making replacements.  CDI is good at firing in less than optimum conditions.  But it's also good for its low current draw from the 12v system, and is good at firing wider than normal plug gaps, which helps light a very lean mixture, for example.

Last spring I made a 2-channel points triggered CDI unit for my Mille, and found that it made the engine harder to stall at off-idle speeds, like when chugging around my hilly, gravel driveway.  It also reduced the several amp current draw of my points system to less than one amp average draw.  After a year of use, I have found no disadvantages, and enjoy the extra battery charging current available.

I have found the dual points distributor to be a big pain when I want to set the timing, and I've also found that currently available points have pot metal shafts staked into the steel base, and that joint tends to get loose.  I had it happen twice, and wanted to get rid of that problem.  Going to the Motoplat distributor with fixed timing and magnetic pickups required a fairly involved project of designing, prototyping and testing a computer based system that controls the advance curve.  After a several months of work by my son and me as time permitted, it's working very well. 

What's left is to work out where the unit can be mounted on various motorcycles, making the right brackets, knowing the needed wire lengths, etc..  That's why I was hoping someone would be interested in being a beta tester, so he could provide me with some installation information and some test time, in exchange for a really good price for a quality ignition unit.

I do plan to make conversion kits for points distributors.  I have to decide if that system would let the old flyweights and springs advance mechanism control the timing as I think the Dyna system does, or if I'd remove that and let the computer do it.  From what I'm learning with my Mille, the flyweights and springs don't always work like they're supposed to, so I'm leaning toward letting the computer control the timing.

[Triple Jim]

I'm waiting on MPG report.

I filled up today, topping it off to where I couldn't get another ounce in like I did last time.  I went 295.2 miles and it took 5.657 gallons, which is 52.2 mpg.  I've checked my odometer with GPS and it's pretty close, like within a percent or so. 

I normally get right around 48 mpg with this kind of local roads semi-twisties rural riding, so that's about an 8 percent improvement.  Of course I'll know more after a few more tankfuls.