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

To me this is very simple.
Camshaft is retarded by a few degrees = Internal de-comp releasing the exhaust valve too early = Higher com-pressure before TDC = Lower crank speed on kick start = Less ignition spark = Hard start.

Click to expand...

Thor

If the CAM is late on the power stroke, the exhaust valve will close late, and the compression will be lower because part of the piston stroke is wasted. In essence you loose compression ratio and hence loose power.

I can not imagin anything that would make the CAM early. If you shortened the CAM Crank distance, with the same number of teeth and the same size chain, the CAM would be retarded.

If the chain or sprockets were worn, that also would delay the CAM in relatinship to the crank.


Are you sure you did not advance the CAM in relationship to the Piston when you fixed it??

WAberg

Thor, Sparks, and others,

In a fit of frustration I ordered a new CDI Coil. I installed it yesterday.

The bike starts fine...less than five kicks cold and first or second hot.

Sequence went as follows.

Bike hard to start....test everything possible...everything looks fine electrically.
Bike hard to start. Replace SEM stator.. No change in symptoms.
Bike hard to start. Have local Husaberg dealer clean carb. No change in symptoms.
Bike hard to start. Change 5K Spark plug cap. Bike actually started again, but still hard to start.

Throw up hands, yell, stomp, beat head against wall....bike still hard to start...don't feel qualified to rip off the valve cover to check cam timing...so I order the one part that never fails...

Install new CDI Coil...Bike starts less than 5 kicks cols and 2 or less hot.

Moral of the story...When you get to the point that you have fixed everything else, try the thing that "never" fails.

I talked to numerous people who told me that had never seen a CDI Coil fail, and in fact my CDI Coil did not actually fail. I could kick through and get a spark. However it must not have been a very hot spark.

CDI systems are made up of five parts.

1. An SCR (Silicon Controlled Rectifier) which acts as a switch. This is triggered by the Black Green 0.8 VAC pulse
2. A full wave rectifier which changes the 30+ VAC from the Black Red into DC current
3. A capacitor which stores the DC current charge from the full wave rectifier.
4. A spark coil.
5. A 5K Ohm resistive spark plug cap.

The capacitor stores the charge.
When the SCR fires, the charge in the capacitor is discharged through the primary of the spark coil.
That discharge results in about 40KV across the secondary of the Spark Coil.
The 5K Ohm resistive spark plug cap, slows down the spark...ie increases the duration..and also cuts down on the EMI...spark plug noise you can hear in an AM radio.

If the capacitor is old and leaky, the charge will tend to dissipate and there is less energy in the spark. If the insulation on the coil wire breaks down, some of the spark energy will be lost there. The SCR is probably biased with some resistors. If they have aged and are no longer the value they should be, they can make it harder for the SCR to reset.

bottom line...maybe the CDI coil never fails, but it can become weak and cause problems.

I want to thank all of you who have posted to this thread...and those who were gracious enough to talk to me on the telephone. I have learned a tremendous amount about my Husaberg.

As a by the by, I have had the IgniTech ignition on order for nearly a month...still have not seen the unit. If anyone else wants to go down that route you may want to check with me to see if I actually receive something. I will install it and give it a try just to let everyone know how it works. It should have the distinct benefit of only being dependent upon a fairly wimpy timing pulse...and of course a 12V battery

WAberg