The most common cause of warm-start problems is the 330-ohm coil. Readings below 300 ohms indicate significant damage to the coil. The defective coil must then be rewound. Depending on the condition of the engine (compression, oil consumption, carburetor adjustment, air filter, etc.), even a 330-ohm coil with a reading of 300–320 ohms can cause starting problems.
A thermal short circuit or ground fault often occurs; that is, the engine starts well when cold, but experiences starting problems when warm. Once the engine cools down, it starts more easily again. Heating causes a ground fault, often triggered by contaminants (oil, moisture, etc.) that heat up, become more fluid, and then penetrate the alternator’s insulation layer.
Caution—the SR's alternator can easily be damaged or destroyed if handled improperly, such as:
Removing the spark plug connector while the engine is running
Kicking the engine without a spark plug connected
Excessive early ignition/engine running too hot. Check with a stroboscope (to be performed after every installation)
It is important to check the idle timing:
SR500 1978–1983: Slotted holes allow for adjustment of the LIMA (check using a stroboscope; The “F” mark must be aligned with the housing mark at idle; starting at 1,950 rpm, the “F” mark must move toward the “early” position. This is the only relevant check. Checking the advance up to 6,000 rpm is not necessary for ignition timing adjustment.
SR500 1984–: Adjustment is not possible because there are no slotted holes.
Using different alternator-rotor combinations can lead to various malfunctions in the ignition system. There are three different types of SR alternators, identifiable by the position of the 330-ohm coil (the largest coil—it stands out!).
10:00 a.m. (1978–1979)
1:00 a.m. (1980–1983)
6:00 a.m. (1984– [better 330-ohm coil])
Of course, different pole wheels were always shipped with the various LiMa models.
There are three malfunctions that can occur if the pole piece and alternator are mismatched:
1. No ignition spark
2. No early ignition; check at low RPMs (starting at 1,950 RPM); this is noticeable when driving in the city
3. Only 20° of advance—barely noticeable during normal driving; unfortunately, there’s only one thing that helps here—rev the engine up to 6,000 rpm and see if 34° of advance is reached.
If you're not sure whether the pole piece and alternator are properly matched, you should definitely test them for the three faults described; otherwise, the alternator will be overloaded during normal driving.
For the sake of completeness, you can also check the ignition coil. It is encapsulated and therefore rarely a source of electrical faults:
Primary coil (orange – ground clip): 0.98 ohms; secondary coil (ignition cable end – ground clip): 12 kOhm (12,000 ohms)
The length of the spark can also be measured, for example, using a spark gap tester. At 500 rpm (with a firm kick), the spark should bridge a distance of 6 mm. Do not perform this test outdoors; instead, do it in a closed, windless garage.
If the good SR is reluctant to start and or the battery is constantly discharged, this may be due to the alternator windings.
This is where the respective coils produce the necessary electrical energy. If the fine copper wires are wound crooked or the insulation is deteriorating, we come into play. We measure all the coils and replace the defective windings and insulation.
We also take care of cables and plugs if required.
If you want us to overhaul your LiMa, you must send in the entire stator, including the base plate and wiring harness. Please do not include the heavy pole piece or the rotor.
The first step is to inspect the individual components: wiring harness, kill switch, ignition switch, alternator (LIMA), spark plug, ignition coil, and ignition wires. Checking the kill switch is often overlooked. This switch sometimes generates a leakage current (either continuously or briefly), which can damage the alternator. It’s often not possible to check this with a standard multimeter. Check the spark at the spark plug. Then disconnect the kill switch and check again. If the visible spark improves, your kill switch system is defective.
It is generally not necessary to check the C.D.I. (ignition module). It is very rarely the cause of ignition problems. In our experience, the most common issue—aside from old or faulty spark plugs—is a defective alternator.
Why does this alternator (LiMa) error occur relatively often?
The coils in the alternator are very sensitive to leakage current, short circuits, and poor contact. The coil wire used must be very thin in order to achieve the required high resistance values in a small space. As a result, the coils are very susceptible to overload. This is inherent to the design and can only be slightly improved even with the best repair work.
Checking the ohm values:
Disconnect the six-pin connector from the alternator wiring harness. Use an ohmmeter to measure the resistance between the wires listed below on the connector. The reference temperature is 20°C:
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