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FS1-E CDI conversion

sidewayscarl
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sidewayscarl
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Joined: September 5th, 2007, 6:48 pm

October 15th, 2011, 4:02 pm #1

I had always intended to eventually fit some form of Electronic Ignition to my partner's - Debbie - Yamaha FS1-E. http://i188.photobucket.com/albums/z24/ ... ham023.jpg[/IMG[/url]]



However this would have to be using readily available parts, preferrably off a Yamaha, and without any modifications to the Fizzy so that the original points based system could be retrofitted if required.
I had a gut feeling that the parts off a QT50 might possibly be able to be used..




Quite by chance when I was collecting a machine from a customer I spotted a Yamaha QT50 sitting forlornly in his farmyard, "Can I have that " I asked, "Of course" the owner said, "I don't want it !"
I took it back to work with me and stripped out the wiring loom, HT coil, CDI box and Generator assembly.. , I kept the crankshaftt and left hand crankcase as I thought I would need this to work out when the Ignition firing point was so that I would have some idea where to position the Ignition Pick up coil...the rest got put in a friends skip ...
I tried the rotor on a FS1-E crankshaft and it fitted !!! RESULT
but the rotation direction was wrong, but I wasn't too worried about this as I had previously fitted a Honda Melody system to a BSA Bantam and managed to get that to work (I had forgotten one thing that was to come to light later however ... )
I chucked everything into a box and took it home with me so that I might investigate at a later date.


As I was at a bit off a loose end that weekend I dragged the Fizzy out of storage and removed the existing set up, to see what might be involved.
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sidewayscarl
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sidewayscarl
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Joined: September 5th, 2007, 6:48 pm

October 15th, 2011, 4:15 pm #2



It soon became apparent that it was not going to be a simple bolt on conversion !!
The mounting holes in the QT50 stator plate didn't line up with anything, so an adaptor plate would have to be made.
I stripped out a spare FS1E Stator plate that I had, and figured that I could probably modify this to allow me to fit the QT50 part into the space available..

I mounted in my lathe and machined away the coil mounts etc until I was left with a disc with a hole big enough to allow the QT50 stator to fit through

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sidewayscarl
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sidewayscarl
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October 15th, 2011, 5:19 pm #3

AS you can see I am only operating from a Garden shed, apart from my Lathe I only have Hand tools to work with ....



The next job was to position the stator plate in the standard QT crankcase with the flywheel to determine roughly where the Ignition firing point was, once I had worked this out I roughly positioned the stator plate in the FS1E crankcase at the FS1-e setting ie 1.8mm before Top Dead centre, which is checked with a Dial Gauge mounted via the spark plug hole,,,

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sidewayscarl
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sidewayscarl
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October 15th, 2011, 5:27 pm #4




Here you can see how the QT50 stator was fixed to the modified FS1E back plate using two countersunk 6mm screws ( you have to Countersink the plate to allow the screws to sit flush, the same as on the opposite side ) - cut off flush on the opposite side, the hole will centre the assembly to a degree but some leeway can be made by opening out the holes to 8mm to allow a little movement - although on the tailor made Adaptor plate that I made subsequently this is not necessary as the inner hole was machined to a perfect fit so the assembly self - centered.
You can also see where I machined a small amount off the rear of the QT50 stator but again this may not have been necessary with the new backplate I made,,, - I actually did this on the Lathe but had to desolder the coils and remove them to mount in the lathe.
With care it could be done with a hand held rotary file...



This is the front view of the assembly

These pictures show the backplate with the first set of slots in whose position I had carefully worked out from the position in the QT50 Crankcase, this puts the Pick up coil in this position ...



I tried with the the stator in this position and got a spark, but the engine wouldn't run, the timing light showed that the firing point was about 45 degrees retarded !!!



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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:03 pm #5

So another set of slotted holes were made and the stator repositioned thus :



Here you can see how the Ignition coil was temporary mounted, and the original wiring harness was connected to the CDI box, at this stage the Ignition system is completely isolated from the machines own wiring.



This time it fired straightaway and the timing was fairly close to where it should be, it only took a couple of attempts ( removing flywheel and moving Stator in the slots ) before the timing was spot on, the QT50 slightly advances the timing as the revs rise, so the timing is set at full advance.. It does this by using the fact that the voltage in the pulse coil rises with speed, this then triggers a circuit in the CDI box to let the spark go earlier, this is why it still advances the ignition despite the fact that the rotation has been reversed, I think the reason why the Pulse coil had to be repositioned was because of the Polarity of the Magnets in the rotor, possibly if I could have reversed the pulse coil wiring it may have worked in my original position, but as this coil is earthed it was not possible...

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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:12 pm #6

So it was a good weekend's work, I dropped the engine down and fed the wiring up into the battery compartment, the CDI box mounted nicely on a spare hole just under the Ignition switch, the QT50 wiring was shortened and adapted to fit neatly, a kill wire (Black /Red) just connects to the Ignition switch in the same way as the original Fizzy method, I have left the original Fizzy HT coil in place as this seems to work OK, the wiring from the lighting/coil charge is the same as original, which in my case is connected to a Honda C90 Cub Regulator/Rectifier which charges a 12 volt battery, the output is a little down compared to the FS1E coil I had fitted, I suspect that this is down to the age of the coil as much as anything, this will only be an issue if I decide to do a long night-time trip which is unlikely, I am confident that everything would be OK if connected to the standard 6 volt system.

I also had to remove the Neutral light switch wire from the original FS1-E stator as this is fed up through the sleeving, I just taped it alongside the other wires, you could feed it through the sleeving if you wanted, or you could make up a new wire altogether...

It was getting late know so I decided to pack up and leave the road test for another time.
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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:17 pm #7

A week went by and I figured that I had it in me to make a new tailor made backplate from scratch, so I spent my first money on the project buying a piece of 5mm sheet aluminium

http://www.ebay.co.uk/itm/290565999747? ... 3D1&_rdc=1



I mounted in the lathe and eventually managed to get it to how I wanted, but I was surprised at how long it did take !!!




I took more care this time and got the plate to be a nice snug fit on the outside of the QT50 Stator and inside the crankcase, it was such a good fit that I had to remove the coil mounting screws to fit the plate over the coils !!








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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:30 pm #8

The new plate was then pilot marked and drilled and tapped 6mm to accept the new Stainless Steel Countersunk screws that I had found during the week.
This was easy this time as the close fit of the inner holes meant the assembly self -centred.



The holes that would form the slots were then drilled using the old backplate as a jig, these were then filed to form a slot, the position worked out to be a bit more than 90 degrees from the Stator mount holes...






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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:37 pm #9

So then it was just a case of bolting the assembly together - with some Loctite "just in case !"



and putting it back in the crankcase..



after retiming the set up with a strobe light the backplate position was marked so that it can be refitted in the same place if the engine comes apart



everything is put back together:









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sidewayscarl
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sidewayscarl
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October 15th, 2011, 6:50 pm #10

So now it was crunch time how would it perform ?
Time for a Road Test...

Firstly it starts a lot easier, no difference in performance - not that I was expecting any, the timing is the same so it should run the same..

Possibly slightly crisper on acceleration, and definitly sems to run cleaner on tickover, no problems at all on a 10 mile test, so I am happy.

The idea was for a more reliable and maintenance free system which it should provide,

If I was to go down the tuning route, varying the ignition timing could improve things, but as Debbie usually only rides her bike on NACC runs which usually means the maximum speed is 30mph, we are quite happy to run the Fizzy as standard, it is easy for her to ride and will now be reliable !!

I have acheived my aim of fitting Electronic Ignition without any modifications to the bike, and the Points set up can be retro fitted if we want. There are no external signs of any modification which is how we like our bikes to be...












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