Suzuki Hustler TS50 (SA11A) CDI info, please!

[ItchyKneeSon]

TL;DR >> Can I make my own CDI? Has anyone done so? Can you help? (If so, high five.)

Hello, all.
I ride a 1995 TS50 2 cycle that came with a racing CDI (hastily) installed. Which was cool until it died and left me stranded. Fortunately, the OEM CDI was still attached and I was able to get home... albeit limited to 60kph (previously 90kph for brisk passing).

I've begun tearing the rev. limiter-removing CDI apart and have found a couple of similar units for sale on Yahoo! Auctions Japan and WeBike, but I'd rather not spend $150 on a bike I'll be selling in the coming months. $5 is far more attractive.

So, my questions are: can I make my own CDI and does anyone have information on how one might go about doing so?


-Itchy
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[ThatDippyTwat]

[Teflon-Mike]

Its a Capacitor-Discharge-Ignition unit.... and its on a very old moped, designed to have points ignition....

Oh-Kay... first up the 'racing' (lol) ignition isn't removing a 'rev-limiter'.. its not rev limited in the sense you probably believe, in so far as when it 'senses' a certain rev threshold, it stops making sparks.....

CDi 'electronic' ignition, for a start, isn't strictly 'electronic' as in everything done by transistors and diodes and programmeable integrated circuits.....

Essential principle of any 'electric' ignition system, is the coil..... an electric voltage is put onto a coil around a hefty iron core, to make an electro-magnet... a second coil around that same core then gets the magnetic field made by the 'primary winding' and induces an elecric voltage in the 'secondary winding'.... this is the principle of the traditional electrical voltage 'transformer'... B-U-T this is the smart bit.... another phenomenon of a coil is that it reacts to a change in voltage, with a 'reverse-voltage' opposing the change.. BUT they dont react with a reverse voltage proportional to the applied voltage, they react with a voltage proportional to the rate of change of applied voltage......

Are you with me so far?

So.. you put perhaps 5v on the primary winding... that has maybe 50x the number of 'coils' wrapped around the core as the secondary winding, which would give a 'transformer-ratio' to step up the out-put voltage from 5v to 250v... all good stuff, B-U-T 250v would not be enough volts to drive a spark accross a half milimeter gap probably even in free air, let alone in a compession chamber with 10x the amount of air and fuel squashed into the same space..... It would take 1000's of volts not 100's to make a spark jump that gap, and that would demand a very big, and very inefficient transformer.... SO, the coil relies on the choke-effect of the reverse volts oposing a change..... remember reactive voltage is proportional to speed of change not the number of coils in the windings....

NOW, you put 5v on the primary winding.... and hold that voltage stable, at 5v... now break the circuit to the primary winding.... it goes from 5v to 0v in however long it takes the switch to be opened.... faster the switch is opened, bigger the reverse voltage the coil reacts with.... and then THAT gets magnified by the transformer onto the secondary winding, and instead of 250v or so trying to jump the gap in teh spark-plug, in a pot, under pressure... you can pottentiallyt get many thousands of volts...... depending how fast you open the switch....

This is not electronic, its pure simple old fashioned 'electrical'... slightly more complicated AC or 'radio' electrical, but NOT electronic.

And if I am actually explaining anything here.... it DOES sort of support Dippy's comments about it NOT being low-level school-boy wiring a plug sort of stuff, it IS probably higher even than A-Level electrical/electronic engineering, because it IS a cross-over between the two.. that would nortmally not be taught to folk until they are doing wuite high level 'trade' qualifications in probably radio engineering, or degree level..... Ie rather beyond a box of bits from maplins and a soldering iron in the bedroom!

But, to continue.....

The CDi ignition unit, is essentially an amplifier... it probably has a small rectification circuit in it as well, because it will take an AC current off the magneto to power itself, and it will need to condition that AC signal to a DC one to put a stable voltage on the coil.. which it will then 'switch' electronically with a transistor, to do the job of old-fashioned 'points' or a switch to turn off the coil and make it react with this enormouse reverse voltage.....

Next up.... it is also, rather like a radio a 'tuned' electrical circuit... not electronic, note... electrical.... to save a complicated mechanical-advance system, which moves the switch around the cam that opens it, to get a different spark timing as the engine revs increase.... it will again use the electrical properties of coils and capacitors that have an inherent 'lag' or phase change in reaction to the input voltage..... so as the engine revs rise, the frequency of the input volts it makes will increase... and by playing with the RCL or Resistrance-Capacitance-Inductrance 'impedance' of the circuit... you can get the 'lag' to change as that happens.... if you do it really well, you can get the spark 'timing' to change.

Another mind-warp is needed though; most mechanical advance systems DO make the trigger, the points move further forwards to 'advance' the time the spark happens in relation to the piston rising in the cylinder, as the revs increase.... CDI systems that incorporate an 'electronic pseudo advance' curve, usually do it by a mechanism known as 'Advance by retard'.... startically, that is without the engine running the trigger is set to make spark at the most advanced point you want the engine to have.... then these RCL effescts reduce the 'lag' between the spark being triggered and the coil occurring, as the revs rise.. so you get the ultimate effect you want... but by a backwards way about it.

Are you STILL following....

Oh-Kay..... You have a coil, making the big volts to make sparks; you have a switch causing the field collapse at fortuitiouse monet to do that, and you have an advance system, that in an CDi bases system is doing it without bog-weights and springs, but some old fashioned 'tuned' RLC radio electrickery..... in which a capacitor is probably being used as a 'soak' to suck volts of the reacting coil very very quickly, to get big reactive spark making voltage.

Your 'Rev-Limiter'.... like I said, almost certainly not a bit of smart programming to kill sparks when revs limit exceeded... remember the system is advance-by-retard, so the 'static' timing is set to give the most advance timing you want the engine to have.... and then retarded at lower revs by the electrickery....

Engine will naturally reach revs beyond which it will run.... and the more retarded the spark timing, the lower that will usually be....

Mopeds, by law were limited to about 50Kmh, and even though the engines could be made to make enough power to go faster.. laws didn't let them.....

Easy way to limit thier speed is to limit thier revs... so using either points of electronic ignition, all you need do to keep them beneath the speed limit is set the static advance at a point that leaves them running out of breath 'early'.

The trigger set mechanically, this startic timing is generally not something you can easily change without some heavy duty mechanical enginering to change the lug position on the fly-wheel and the sensor position on the stator, to shift the sensor further round teh crank, so that the max advance is more... you may get some slotting plates so you can twist them a bit further, but probably not more than half a degree or so.... and you likely need change max advance from something like 7/7 deg before top-dead-center, to perhaps 12-14deg BTDC....

Using an alternative bit of electrickery, you might get a 'retard' response, that is different to standar, and may help the ignition hold a bit more advance further up the rev-range, but you are still meddling in the margins.. advance by retard you will NOT get the advance curve to make a spark before its triggered....

So, its NOT just a case of replicating either the OE CDi unit or the (lol) racing' one of e-bay....

Oh! And the advance curve is just one variable to an engine's operating perameters... for a given engine, of given valve or port timing, you have a 3d graph relating the optimum advance, not just for any given RPM, but also for any given throttle opening, and given fiuel-air mixture strength....more whether the engine is holding a steady sped, accelerating or decelerating...

Highty qualified and highly trained technicians have to spend thousands of hours with any engine on a Dynometer, making tweeks and changes to the ignition timing and the mixture strength, to get both 'best power' and 'best ecconomy' from the ignition and fueling maps of modern engine..... and then tweek that more still to meet the requirements of modern emmission regulations.... but still, its no small chore.....

Could be done by an ameteur in the shed with a home made brake and a bit of know how and enough patience.... but, DIY, withouy doing that, best you'll be able to do is make a best gues at what optimum settings may be, based on what has been used or been found best by other people, probably on other engines, and almost certainly not with your own concoction of electrickery, that may or may not have the same advance response....

Do you STILL think that you can knock up a CDi unit in your bedroom with some bits from Maplin and a soldering iron and a circuit scematic off the internet?

Actually, following the instructions to the letter, you probably can!!

You dont need to know how it works to put it together! B-U-T the box of components you would have to buy from Mapilin, as well as anything else, PROBABLY mean that by the time you had... you would have not only spent more money on it than something off-ebay from China built in a sweat shop to do the job.... but more than something from a main dealer.... probably also made in a sweat shop in china, with a Suzuki part number cast in the lid......

In fact... There Is a thing called a MegaJolt 'ignition system', which is an 'open-source' self build electronic ignition system, intended primerly for US hotrodders and thier V8's, but, can pretty much be used on any four-stroke engine that needs a spark-ignition system, from a single cylinder garden strimmer to a 12 cylinder radial aero-engine!

Based around proprietry automotive components you can get at any motor-factors or off e-bay for a Cheverolet or Ford or Chrysler, even a Mitsubishi or Toyota.... its intended to make the job of DIY building your own electronic ignition system 'pretty' do-able... and I believe that some-one on here DId actually use such a system when they built a kit car.....

This WOULD by a long shot be your easiest and simplest and most sure to work, way about DIYing your own CDI unit come ignition system..... B-U-T, if you think you can make something in your bedroom from component parts and an old sandwich box, with a soldering ioron and a bad idea for LESS than you can buy a unit designed for the job, of e-bay, you are really, REALLY hoping...

End of the day its a moped... it aint NEVER gonna be fast... be thankful you dont have to pedal!

Some illconsidered after market ignitgion unit has been fitted... and broke... boo-hoo... you have binned it, and gone back to the original fitted by Suzuki... and it runs!

To my mind that's a win... and if you want cheap fix, they dont come much cheaper... and good odds that the bit fitted by Suzuki wont go 'pop' like the one fitted by former owner has....

You want to go faster than a moped is designed to go... there are plenty of motorbikes sold designed to do that, off the shelf, no faffing with a soldering iron required... and most of them will go a heck of a lot faster than a messed with Moped ever will....

The accredited Land-Speed record for a 50cc motorcycle is STILL under 70mph, and that with a full on competition engine, built and prepared by a team of highly trained and experienced engineers to run, for oooh.... maybe 3 minutes? not have to idle, not have to go up and down hills or respond for corners, let alone traffic, etc... running on special high octane fuel, not the stuff you get out the pump at your local filling station, with permitted streamlining, super skinny tyres and a rider probably barely much bigger than a toddler...

You will NOT get an over thge counter moped to go anywhere near that speed... and the quickest and easiest way to even try... would be to bore the thing out to as many more cc's as you can! You'd get 70mph with as little as 70-80cc 'big'bore.... and no other major mods! Probably wouldn't last too long, and blow up rather regularly... I know, I done it! BUT.... you would get the speed.... just not all that cheaply, and certainly not as cheaply as a can of lager!!!

Your call.... if you have read all that, let alone understood much of it, you are probably by now old enough to get a licence for something bigger than a moped, you can buy over the counter, for no faffing with soldering irons, that will go, go fast, and shouldn't go bang or stoip sunning because of some ill-concieved mod you have made with half clue what you are doing, but a lot of optimism what you hope to achieve....

BTW... I managed to get a one-way timed speed of 65mph out of a Yamaha DT50, many decades ago..... over a measured half mile...... Yup... the engine didn't want to run much further... soi I never got the other half of the two-way timeing rin in on it! It was also bored out, quite a bit bigger than 50cc... and my Grandad thought it was a good-laugh... thoiugh I think that was mostly him watching me sweat pushing the ruddy thing home every time!!!

TLDR... NO.... you will not fix this bike for $5 and make it go as fast as before, or faster.... might break down as fast... but that will be about all... and you will almost have to spend more than five-bucks to get it to do ANYTHING.... this is the real-world, you wont get back to Kansas putting on a pair of red shoes and clicking your heels together three times!
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[ItchyKneeSon]

Thanks for the replies, gents.
So, what you're saying is there's a reason aftermarket CDI units go for $150 used?

I called it a 'racing CDI' because <50cc bikes are legally limited to 30kph on public roads here in Japan and the Kitako Power Rev CDI unit (shown below) is referred to as a 'リミッターカット' or 'limiter cut' in Japanese. It previously allowed me to rev up to 10k RPMs in every gear.

https://auctions.afimg.jp/item_data/image/20140115/yahoo/b/b152684344.1.jpg

I noticed that the stock CDI only allows the bike to redline in the first 3 gears. The latter 3 are limited roughly by speed. Sometimes, I'm able to push 6th gear to 62-63kph. So, rather than trying to scrap together a CDI from scratch, I imagine there's a way to 'trick' the unit into thinking gears 4-6 are 1-3, or something of the sort. After some searching, I've found a couple of people who appear to have done just that, but I've been unable to get a reply after my inquiries.

Another thing that I noticed is the connector of the aftermarket unit is missing a 5th wire that is present on the stock unit. I'm guessing this is the signal indicating gear selection. However, I could be mistaken.

One guy mentioned there is a hidden hint do unlocking gears 4-6 shown in the schematics of the TS50 Hustler Repair Manual. But, I haven't splurged on one of those quite yet...

Does anyone have a TS50 Hustler that's possibly done this kind of mod?


Regards,

Itchy
____________________
Need parts from Japan?
PM me and I'll try to work my magic.
While I'm still here...