sem's charging coil replacement!

Almost done that.
Not on the SEM though, it was done on a 50 cc Victoria moped engine.
A transformer rated at 4W @ 50/60 Hz was (more than) enough! There was no regulator to bring the AC out of balance. The frequency was not as high as the sem will give in a husa engine. The discharge capacitor was only at 0.5 to 1uF and 400V. So it was easier to make it work. It even overcharged the capacitior and eventually it... Umm... Didn't I describe this previously? Wait a bit...
Here:http://www.husaberg.org/index.php?name=PNphpBB2&file=viewtopic&t=2408&start=0
Diodes and especially bridges for 50/60 Hz are not optimal, the berg will produce up to 1000 Hz. The Victoria couldn't have produced much more than 100 Hz! Try fast diodes instead. Also, try to run it without the smoothing capacitors. The voltage from the original charger coil is far from smooth. Also, the regulated electric tension from the lighting coils is AC with overlayered DC which is something that transformers do NOT like, the DC part that is. DC will lead to magnetic saturation and excessive heat build up in what you use as the primary winding (which was originally intended as a secondary one). Either filter the DC out with a large bipolar capacitor or else get a symmetrical regulator.Then will perhaps your small transformer be more than enough in your case too.
Maybe could one lighting coil be used unregulated if a suitable inductor was connected in series to protect the discharge capacitor from too high voltages at high revs. But that would take some experimenting.
A 100 VA transformer for 50/60 Hz is a bit too large, if you can get an aircraft transformer, they are designed for 400 Hz and are much smaller for the same power.
Your trick with a transformer is definitely what I'll try as soon as the stator breaks. But it has been around for a number of years and it just won't quit. But when the day comes...
An inverter is an alternative. Especially if the bike has got a battery. Emco is one inverter brand that could be considered unless you want to design your own.

Good initiative with the transformer. Thats the way they should have been built from the beginning.

Regards

The voltage drop can also come from the diodes if they are not well chosen as well as from the smoothing capacitors. At the higher revs the regulator skews the waveform to give more DC and all these things will work against you as revs goes up.
The classical 555 is great for many things. But look at for instance IR2153, IR2155, you will be delighted!, and there are probably even newer and better stuff around nowadays. These are bipolar oscillators and drivers in the same package and are useful with ferrite transformers operating at very high frequencies which therefore can be very very small for the power they produce. I'm sure that you can find suitable application notes on the internet to inspire you to make a good design. HOw much power does the discharge capacitor really require?, it should be possible to calculate it somehow. It will be proportinal to the revs, me thinks.

I hope to read about your progress here at the forum in the near future.

Regards

Hello OIK and Smorgasbord

I have electrical troubles with my FSE 650 2002. It seems that the SEM charging coils are the cause (but i'm still not shure). Please take a look at my new topic at http://www.husaberg.org/index.php?name= ... pic&t=6998.

Are you in the opinion that the method you described in this topic "sem's charging coil replacement!" could be easily applied to my 2002 berg ? Any changes should be implemented ?

One more question (which might sound stupid but please take account that i'm not an electrical engineer..) : do the lights still function with your method ?

Thank you in advance for your reply.

does anyone have a diagam to do this conversion , i am prepared to try it out , and i see no reason why it should'nt work perfectly, i have a spare cdi so , if it blows , then it blows, i have heard that sparks does an excelent job on sems , but no one made any progress by not experimenting a bit?and why oh why do we need to use these stupid four little unreliable coils anyway, as we know that they are going to pack up eventually and leave us stranded miles from home.I just wish someone would manufacture a complete ignition set up that is as reliable as japanese electronics, they would soon be very very rich, and i would buy one .

scrapveiw said:

does anyone have a diagam to do this conversion , i am prepared to try it out , and i see no reason why it should'nt work perfectly, i have a spare cdi so , if it blows , then it blows, i have heard that sparks does an excelent job on sems , but no one made any progress by not experimenting a bit?and why oh why do we need to use these stupid four little unreliable coils anyway, as we know that they are going to pack up eventually and leave us stranded miles from home.I just wish someone would manufacture a complete ignition set up that is as reliable as japanese electronics, they would soon be very very rich, and i would buy one .

Click to expand...

I think Oyk rides his on the road I think yours is enduro, the transformer could be a bit vulnerable to water and dirt and once in these conditions you might find the electricity going else where to where it should, OK if you can keep it dry.
The only reason the OEM ignition stator is so unreliable is the way it is put together and the quality of materials used, where mine are totally different.
I give 12 months guarantee with my rewinds and after over a 1000 out there I am yet to see one returned.
As for the Japanese ignitions I have rewound bucket loads of them they used to fail for the same reason as the SEM but in later years they have become very reliable.
But feel free to go down the transformer route it is an interesring experiment and I'm sure it could be very reliable.

Regards

Sparks.

thanks for the replies guys, i tried the transformer route and it works! but i still have the same problem allthough it did run better, but when i stopped it ,it would not restart.thats what it was doing before, ive checked the valve clearances ,checked the cam timing ,messed about with the auto decomp, changed the carb , changed the sem,changed the coil pack,changed the plug?checked all the ohms readings, even changed the flywheel...and then i put it all back to original wiring spec because the spark jumped 10mm on the original set up?????.....what else can it be , i am beginning to think that i have been supplied with a duff plug,and i was still at it at 3 am this morning, but then it back fired again and the kick start snapped in half when i was tryin to kick it up for the millionth time, my left leg is now thicker than my right,HELP!!!,i feel like taking a hammer to it.ive been a mechanic for 22 years and some of those years were as a motorcycle mechanic too. ive got to admit that this one has realy got me scratching my head..........regards......ian

forgot to say , its a 1995 fc501 ,

cured it , i think, the problem was a brand new NGK spark plug!, went to the bike shop this morning and purchased 5 new plugs , i put the first one in gave it a bit of choke and a good hard kick and she fired up and ticked over like a brand new berg, and it restarts now .....but , oyk when you read this i would still like to go down the transformer route so that i can attatch it to my bike and use as a switched back up just incase, the sem dies when i am out, i used an old trans former out of an old radio cassette 220/9v , it worked fine, i then tried one out of an old TV which was 220/12v but was twice as big in overall size than the radio cassette one it produced a spark but it was weak, also my generator lighting circuit has two yellow and one blue ,i had to join the two yellow together and use the blue to make the circuit to the transformer, is this ok to do that?..........regards .....ian.

thank you for your info, the rad cassette transformer did actually allow the bike to achieve maximum rpm with no hiccups , i think the best thing to do is get a transformer identical to the one you are using and go from there, because yours is still working with no probs,the bike i have has all the lighting circuit including regulator and they worked ok, so i can regulate it, i did go and buy a 220/12,100va lighting transformer from the local electrical store , but i was dissapointed to find that it is not a true transformer inside , its full of capacitors and semiconductors chips and things and two circular very tiny coils , so cant be used , hence the radio cassette and telly transformers, so what i need is the exact make and model of your transformer , i looked at the pic in your album but i cant make out all the writing on it. you are a clever chap and have been a great help ...thank you .....ian