Starting problems 1995 FC 501, Street Legal, SEM ingnition,

Starting problems 1995 FC 501, Street Legal, SEM ingnition, Dellorto VHSB 38, WAberg Seattle WA USA

I am new to Husaberg and the group so I need a little help analyzing my problem and deciding on the best solution.

My current state of affairs…the bike is hard to start, but runs fine.
I have read many posts, but have gotten a little confused.

Here is my data . All measurements were taken with a Fluke 189 DVM with max hold capability.

Max Spark using adjustable gap method … about 2/10th of an inch which I think is about 12KV As I understand it, this is at least 40% low. As I understand it 20KV (0.3 inches or 8mm) should be the minimum with 30KV ( nearly ½ inch) being quite reasonable for a new system.

MY SEM Stator measurements

Loaded
Black to Red .. many hard kicks with no spark plug.. 40 VAC MAX average reading
Black to Green … many hard kicks with no spark plug. 0.8 VAC MAX average reading

Unloaded
Black to Red 1578 ohms 46 VAC
Black to Green 22 ohms 1.0 VAC

Coil Measurements
High Tension lead to ground 7200 ohms

My analysis…please check for sanity…

The trigger voltage is low at 0.8 VAC which will account for the fact that the spark fires some times and does not fire other times while doing the spark plug removed kick through test even at 2/10ths of an inch. This indicates that the stator needs to be replaced or rewound for the trigger voltage problem.

The Coil Charging Voltage (Red Black loaded) of 40 VAC seems to be quite adequate according to what I have read. If that is true and the max spark voltage is 12kV as shown by the 2/10th max gap spark test, that would indicate a problem with the coil/black box.

It is my impression that the minimum spark should be 8mm or about 0.3 inches ie about 20 kV I am only getting around 0.2 inches and that is intermittent due to the low trigger voltage of about 0.8 VAC max. A smaller gap gives a much more reliable spark.


I think I have three choices.

1. Have Sparks rewind my existing stator. About $200 after the dust settles.
Up Side…This one will probably have a better life expectancy because of better wire and craftsmanship.
Down Side…This does nothing for the Coil / Black Box if there is an issue there.
Second Down side…The bike will be down for three weeks to a month while the stator is being shipped to Spain, rewound, and shipped back to me.

2. Buy a new KTM 580.31.002.050 as others have done and install it in place of my existing 1995 SEM stator.
Up Side. $160 and the bike is only down long enough to change out the part.
Down Side…after a couple of years of riding this stator is likely to deteriorate and I am back to the same old problem.

3. Buy a DC-CDI-P from IgniTech, replace the existing Coil / Black Box with a dumb coil. About $250 for the parts and pray that I can figure out the relation between the falling edge of the timing pulse and TDC. I think it should be about 32 BTDC…need some help here. This is a reasonable option since I am an EE and I have a reasonable amount of electrical test equipment at my disposal.
Upside… fight with some timing issues, and I could have a modern, fairly bullet proof, system.
Down Side…I could be starting a new saga that takes way too much time to complete.

Is there a fourth option that I have missed??



I need a bike that starts reliably. The idea of being 30 miles in the boonies and standing on a stump kicking for twenty minutes to get the bike started is not a reasonable option.

Key Questions:

Is the coil marginal? The numbers I got do not seem to jive with what I saw on the site…. I have 12kV and I should have 20kV minimum, but the coil charging voltage (Black Red )seems adequate at 40 VAC loaded.

If the coil needs to be replaced, where do I find one? I read one post that indicated that the SEM Coil / Black box was $468

If I stay with the original style ignition, it seems to be a no brainer that the stator needs to be replaced due to the low trigger voltage..ie 0.8 VAC loaded. Right … Wrong… need a little help here.

If I go for the DC-CDI-P system, does anyone know the relationship between the trigger pulse on Green and TDC??

WAberg
TFox
Terry Fox
Issaquah WA
[email protected]
1995 FC 501 Street Legal, reserve tank on right rear number plate.

Starting problems 1995 FC 501, SEM ignition, Round 2

Starting problems 1995 FC 501, SEM ignition, Round 2

I have just replaced the SEM Stator with one of the KTM units. Resistance was correct on both the Red and the Green.

The spark is jumping a gap of 0.37 inches

The Black Red generates 38 VAC Max loaded and 44 VAC Max unloaded

Black Green…ie the trigger pulse is 0.8 VAC Max Loaded and 1.3 VAC Max unloaded.

Although I have read that some units need as much as 3.5 VAC loaded in order to fire, it is my opinion that 0.8VAC Max is quite reasonable. This is assuming the trigger pulse is directly firing the gate on the Thyristor. That gate is simply a PN junction and assuming it is silicon, it will be forward biased at 0.707 volts and will be drawing considerable current by the time it reaches 0.8 VAC where both the old stator and the new stator perform.

One odd thing is that if you kick it through and the spark tester does not take the load, the spark will become very intermittent unless you let the bike sit for fifteen minutes. This seems to indicate that things go amiss when the spark plug is not there to take the load. Once that happens, there is no spark…so go have coffee and come back later.

With that said, the bike is still very hard to start..I am going to start trouble shooting the carburetor next.

Any other suggestions…I may take Bucklee’s suggestion and haul it down to Cycleworks.

California is reputed to be one of the tougher states on this issue. I would go to BajaDesigns to get more information on lights & dual sport kits in CA.

However here is a list of the items added to the bike.

1. DOT Tires
2. An Electrical system.
3. DOT dual level head light
4. Tail and Break lights with break switch
5. Horn
6. Turn indicators front and back
7. Rear view mirrors

WAberg

jwilly,

I am located 18 miles East of Seattle

WAberg

Back to the technical stuff.

I installed the KTM Stator...kicking it through with no spark plug...big spark ..almost 0.4" but intermittant.

Very hard to start ..only fired once in 20 minutes of kicking

Installed "Sparks" stator, had carb cleaned at local bike shop. Big spark, but Spark is intermittant.

Talked to BOSS, replaced 5K spark plug cap.

Good reliable spark with no plug in bike...ie kick spins faster without a plug

Intermittant spark with plug in ...does not spin so fast.

The only thing I have not changed is the fly wheel and the coil unit.

Since the issue is intermittant spark, which was the original issue, I must deduce that the trigger is the issue..ie green black. Either in the Stator / magnet section or in the CD Coil trigger section

I have read posts that said that I might need up to 3.5 volts to trigger the CD Coil. I do not see any way to get that kind of voltage out of my machine without changing the flywheel magnets.

I think this is fundamentally a poor design.

Being a good engineer, I am going to tear out the CD Coil and test it. I will find out exactly what it takes to make it fire.

However, in the long run, I think this is an inherently weak ignition design and getting everything perfect will make it barely acceptable.

Hence I am going to forge new ground and order a CD ignition form the boys at Ignitech.
If it works well, I will be happy, if not...I will have a very strong running, street legal, but damned hard to start Husaberg for sale.

WAberg

Hi ThorsHammer,

At the moment the issue is a reliable spark. I am actually testing the spark. The triggering is just on the edge. If I kick VERY hard, I get a spark with the plug in.

Anything less than a Superman kick and no spark or maybe a spark every three or four kicks.

The only things that are in the circuit for the spark are

1. The SEM Stator
2. The magnets in the fly wheel
3. The CD Coil unit
4. The high tension lead and the 5K cap on the plug

The decomp seems to be just fine. I can kick the motor through at a very good RPM.

The issue is a reliable spark at kick through speed.

The original problem was the bike was hard to start but then ran perfectly once started.
I could kick for 15 minutes without even so much as a pop...then it would run and idle perfectly.

I could change out the fly wheel to get new magnets or I could get a new CD-Coil unit, but the voltage comming out of the stator seems reasonable according to all I have read on the site.

I can change out the CD-Coil, but everyone I talk to says they never go bad.
The flywheel is a pricy item and that is the only way I could possibly get a bigger voltage on the trigger. I am reluctant to buy one just to remove it from the list of possible problems.

The CD-Coil is $175, but how do I know it will trigger any more reliably than the one I have in the bike now??

If I go to a CD ignition I will be polwing new ground, but once I get there, I could have the worlds worst SEM stator and the thing will still give a big spark at slow speeds.

I am an EE and this has become a point of personal honor. I test things and when they are not right, I would like to know why they are not right. In this case I believe the SEM ingition is just a very marginal design that can work reasonably well when everything is perfect, but deteriorates rapidly when things are not perfect.

If I could get a new CD-coil and simply test it to see how much trigger it needs, and then compare it to mine, that might make me feel better. However, from my engineering background, I know to fire a silicon thyristor, the gate must be forward biased. That takes atleast 0.707 volts minimum. If there is any loss in the system, the 0.8 AC that I am measuring at the green/black leads, may not be enough to turn on the thyristor.

I am tired of throwing parts at this thing without making progress on the original symptom...intermittant spark at low speed.

A little frustrated, but I am going to get through this thing.

WAberg

Thor,

I just got the bike fired up. Same old thing..hard to start then runs perfectly.

The de-comp works and I can kick the bike through with good speed.

I am having trouble understanding why the de-comp opening a little early or late would make a big difference.

Aparently it was the silver bullet on your machine.

Are you saying that with the de-comp late in he cycle, there might not bet enough compression to fire??

or


If the de-comp was early, it would be more difficult to kick through effecting the speed of the kick hence the energy in the spark.

I can even hit this thing with starter fluid and it makes no difference...hence the reason I am more suspicious of the spark. I am use to having an ignition that will blow the carbon off a spark plug and leave a spark that is long in duration with plenty of energy to ignite almost any conceivable mixture.

If I had that super spark, then the mixture could be farther off and still start. By the same token, a flooded machine / wet plug fires just fine with a better spark.

I don't know. I will do some reading and attempt to check out the cam timing.

WABerg

Thor, Sparks

I am trying to noodle my way through the valve timing / hard starting / runs great argument.

I suppose the logic would go like this.

As the timing chain / cam gear / crank gear wears, the cam becomes further retarded in respect to the crank shaft.

The de-comp holds the exhaust valve open up to 85 degrees before TDC. .in other words, the last 85 degrees of crank shaft rotation is compressing the fuel air charge...when things are working perfectly.

If the cam is retarded by a few degrees, the de-comp is not allowing compression until after 85 degrees before TDC. If there are approximately 12 teeth on the CAM shaft grear and I am half a tooth off as Thor found on his machine, that would mean that the de-comp is not out of the circuit until 70 degrees before TDC. ie the last 70 degrees is compressing the charge, not the last 85 degrees as in a perfect system.

From this explanation, I am willing to agree that the fuel air charge would not have the same compression if the CAM was retarded by 15 degrees or approximately ½ tooth.

Can this small difference in compression have a big effect on the ignition characteristics of the fuel air mixture??

What determines when the cdi coil fires?

When running normally, the cdi coil is firing at about 32-36 degrees before TDC. If when, I kick start the bike, the spark fires at 30+ degrees before TDC, I should feel a big shock in the kick start mechanism. I do not feel that so the firing of the plug at slow speed must be considerably retarded.. hopefully past TDC.

Is the spark retarded when I am kick starting the machine??

This is over my head…any answers out there??

A simple test of the de-comp theory should be as follows…. Roll the bike down the hill and bump start it. If it starts easily, every time, that would lend great credence to the valve timing argument.

Is there any other way to validate the valve time argument on my particular bike??



WAberg