Powerdynamo, problems with PD systems for triples

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ignition problems on PD systems for 3 cylinder  (triples) 2 strokes

We sell quite a lot of systems for various triples and in most cases the customer is satisfied with performance.
We get however also customer feedback that
 
  1. Starting with possibly existing electric starters does not start engine, whereas kickstarting it works well.
    The system needs a certain starting speed (about 350-400 revs/min) to develop enough energy for sparks. This energy does not come from battery, but from magnetic field inside generator. It seems that some starters are not fast enough for this.
    As the resistances in the high tension circuit (resistors in plug caps or in plugs themselves) increase the needed starting revs you should not use more than 1 kiloohm each. See our information on this here
  2. after installation of the system customers sometimes report that the system does not permit their engine to rev beyond something like 5000-6000 revs/min.
We now have researched the problem in some detail, both  on our test bench and in a street ready H1E for test. We also have looked  at all customer feedback on the matter.

On the bench we could spin a system returned to as as having this 6000 revs problem up to 15.000 revs with stable ignition, but there was no compression. The test H1E reached 9000 revs, but with spark plug gap set to 0.4mm

Good question now what happens here in  6000 limitation cases? The answer is surely very complex as we talk about old and rather complicated engines.
  • reducing spark plug gap to 0.4- 0.45mm in many cases did help the problem.
    we explain this as follows:
    there are 3 sparks every rev. at 6.000 this is 18.000 sparks. at the same time the rotor is (to get the needed 3 pulses) lacking 3 magnets and hence not at full capacity. at the point of about 18.000 sparks available energy to load the 3 condensers (one each in ignition coil) seems to be at critical level to make spark jump 0.6mm gaps under compression. reducing the gap helps this and seems to be the main solution.
  • a customer reported good results by using NGK gold palladium spark plugs (B - HV range) with fine wire centre electrode
  • further, we found that experimenting a little with ignition timing also helps the 6000 problem. Here good results have been reached with  Ignition timing set at 3.4mm btdc, (this is pretty much standard advance as advised by Kawasaki
  • in some cases the problem could be helped by increasing fuel richness (higher position of carb needle and/or bigger main jet)
  • also it seems to happen if you use different spark plugs and/or plug caps on the engine. All 3 should be same, also spark plug cap. Never use spark plugs with inbuild resistor and never use resistor caps with resisitor of more than 1kOhm. Do not set spark gap to more than 0.4mm and make them all same.
  • Make sure you have good ground on all ignition coils by having screwed the brown wires going with the wire bundle to them screwed directly to the metal coil frame.
  • Also timing may be wrong.
  • On one engine with such a problem, we found that it did run only on 2 cylinders. So, should you experience such rev limitations, check that all 3 cylinders are running.

The following is valid for all Kawa Triples (turning anticlockwise)

Have a look at the drawing left below. Note the 2 small coils (they are black on the stator) at a 11 and 12 o´clock position. About level of the right such coil is one of the 3 holder screws for the stator.

We take this screw as a reference. The correct timing mark on the base plate should be 17° left of this screw.

The Kawa handbook gives for the  triples about
23° BTDC as ignition moment. With the first piston on TDC, the laserd on marking line on the rotor should be 23° left of the marking on the adapter plate and 40° left of the reference screw.

(click pictures to enlarge)

 





The system for the Suzuki GT750 (73 28 79 00) turn clockwise.
Here the marking is at a different position, 12 degrees clockwise from the reference screw.

the halfhole for the fastening of the plate is on the center line to the reference hole, so you may use its middle as start for measurement. As plate diameter is 130mm, the corect marking should be 13.5 mm to it right

  • the problem has NOTHING to do with battery or lighting voltage of the system as suggested in some forum.
    lighting circuit and ignition circuit are NOT connected.
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