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
with possibly existing electric
starters does not start engine, whereas kickstarting it works well.
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
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
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
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
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.
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.