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4 questions about old motorcycle ignitioin system.

M

mm

Jan 1, 1970
0
4 questions about an old motorcycle ignition system. Electrical
questions are 2 and 3, and maybe 1.

Well, I got my '69 Honda CB450 reassembled, just in time for the last
2 days of warm weather.

1) I tried to start it and it didn't start, and I had other things to
do for 2 or 2.5 hours, and when I got back to it, I saw that I had
left the ignition switch on**. This model has two carburetors 2
coils, 2 sets of points and 2 condensors. One coil was warm, and it
had 1 to 2 thimbles of waxy stuff which had come out of it. Did I
ruin the coil? If not yet, will it die in 5 or 10 hours of use? Is
there some way to repair the damage I did? (It's not clear I'll be
able to find a new set of coils for a 1969 motorcycle.)

2) One set of points was open and one was closed. I put a thin piece
of cardboard between the closed points, turned the ignition on again,
and measured the voltage across the points. The circuit is battery
plus terminal - coil - (points/condenser, where these two are in
parallel with each other) - ground - battery negative terminal. So it
seems to me that the voltage should be battery voltage, about 12
volts. Or should it be less until the condenser fills? The voltage
was 6 volts using an analog meter, and didnt' seem to be going up. I
thought, Oh my gosh, I've run down my brand new battery, but when I
checked the voltage there, it was at least 12.5.

BTW, how much damage *did* I do to the battery by running one ignition
coil for 2 to 2.5 hours?

3) On the other circuit, I tried to evaluate the other condenser by
turning the ignition off and measuring the resistance across the
points, which I'm pretty sure is across the condenser. I expected to
see the resistance pretty low as the condenser filled and then
increace. But the resistance was close to infinity. If I tested
right? that means the condensor is open, but that shouldn't keep the
cyclinder from firing, right? IIRC, mostly what it means is that the
points would pit quickly?? If I can't get the right condensor
quickly, what value and type would I need to jerry rig one
temporarily?

4) There is a wick that lubricates the cam and keeps the rubbing
blocks from wearing out. I can't remember what I'm supposed to put on
the wick. What do I use, and if they don't still sell it, what do I
buy instead? :) (I had trouble remembering this 30 to 20 years ago,
too, but I haven't had to worry about it since I've had
all-elecctronic ignitions on my car)


**If it had started, I would have remembered to turn the ignition off,
but since it didn't, I didn't. My fault.

BTW, the starter motor worked well, even though I hadn't checked it
out, and the kick starter seemed to maybe be working well, or at least
differently, even though it would go so far and then stop dead without
cranking up till now. The clutch disengaging is working fair, and the
throttle doesn't spring back quickly enough, even though I oiled all 3
cables (2 carburetors) and the throttle plates moved easily after
soaking the carburetors in Permatex.
 
P

PeterD

Jan 1, 1970
0
1) One coil was warm, and it
had 1 to 2 thimbles of waxy stuff which had come out of it. Did I
ruin the coil? If not yet, will it die in 5 or 10 hours of use? Is
there some way to repair the damage I did? (It's not clear I'll be
able to find a new set of coils for a 1969 motorcycle.)

It is possible it will fail, or has failed. Warm? Not hot? it is also
possible it has water contamination already.
2) One set of points was open and one was closed. I put a thin piece
of cardboard between the closed points, turned the ignition on again,
and measured the voltage across the points.

Typically the point surface (the contact) will burn or oxidize. I'd
recommend replacing the points.
The circuit is battery
plus terminal - coil - (points/condenser, where these two are in
parallel with each other) - ground - battery negative terminal. So it
seems to me that the voltage should be battery voltage, about 12
volts. Or should it be less until the condenser fills? The voltage
was 6 volts using an analog meter, and didnt' seem to be going up. I
thought, Oh my gosh, I've run down my brand new battery, but when I
checked the voltage there, it was at least 12.5.

BTW, how much damage *did* I do to the battery by running one ignition
coil for 2 to 2.5 hours?

About a million dollars worth... <g> This happened to cars all the
time. Usually damage is limited to burning the points and should not
damage the coil.
4) There is a wick that lubricates the cam and keeps the rubbing
blocks from wearing out. I can't remember what I'm supposed to put on
the wick. What do I use, and if they don't still sell it, what do I
buy instead? :) (I had trouble remembering this 30 to 20 years ago,
too, but I haven't had to worry about it since I've had
all-elecctronic ignitions on my car)

Ignition point cam grease. It's special... (Really!) probably hard to
find, but whatever you use do not apply too much!
 
D

default

Jan 1, 1970
0
Those old bikes are easy to keep running, they are relatively simple
to fix and adapt parts to them.
4 questions about an old motorcycle ignition system. Electrical
questions are 2 and 3, and maybe 1.

Well, I got my '69 Honda CB450 reassembled, just in time for the last
2 days of warm weather.

1) I tried to start it and it didn't start, and I had other things to
do for 2 or 2.5 hours, and when I got back to it, I saw that I had
left the ignition switch on**. This model has two carburetors 2
coils, 2 sets of points and 2 condensors. One coil was warm, and it
had 1 to 2 thimbles of waxy stuff which had come out of it. Did I
ruin the coil? If not yet, will it die in 5 or 10 hours of use? Is
there some way to repair the damage I did? (It's not clear I'll be
able to find a new set of coils for a 1969 motorcycle.)

One set of points stays closed pulling 3-5 amps down through the coil
and dissipates ~60 watts. That's an unhealthy amount of power for 2+
hours. All the power is dissipated in the primary winding and if it
didn't get hot enough to melt the enamel on the magnet wire it will be
good to go.

Measure the resistance of the primary and compare it to the cool coil.
You may not be able to discern a single shorted turn with just an ohm
meter, and a single shorted turn will adversely affect the operation,
but it is a place to start . . .

I did something similar with my Triumph twin - heated the coil
something fierce because I left it on.

You don't say how your coil is made. The old Triumph had a coil that
was in a metal can and filled with oil - like an auto coil. A lot of
Jap bikes use molded coils. If the stuff oozed out and the primary is
still OK - the coil still works(?) then you still may want to give it
an epoxy coating to keep moisture out. And the waxy stuff is probably
wax - wax was used in old plastic cased coils and expands a lot when
heated.

My technique for flaky coils with cracked plastic cases works well for
keeping water out:

Big obvious cracks - Clean surface with a wipe of acetone, if it is
glossy smooth I rough it up with sand paper (not emery - it is
conductive) or a file, then just apply some silicone to the crack -
work it in and around the area.

If the coil may already have moisture in it, I dry it, then place it
in a warm (150F) oven overnight or use a light bulb and tin can to
heat it gently. Air has to circulate around the coil as it is warmed
so don't close it up tightly leave a way for fresh air to get in and
carry the water vapor off.

Plan B: Dry coil, prepare surface - paint entire outside with epoxy -
thickened epoxy that sets slowly is best. I have a rig with a motor
that slowly rotates the coil along its axis for an hour as the epoxy
cures - that technique is best when it is an older coil subject to
lots of hairline cracks in the case.
2) One set of points was open and one was closed. I put a thin piece
of cardboard between the closed points, turned the ignition on again,
and measured the voltage across the points. The circuit is battery
plus terminal - coil - (points/condenser, where these two are in
parallel with each other) - ground - battery negative terminal. So it
seems to me that the voltage should be battery voltage, about 12
volts. Or should it be less until the condenser fills? The voltage
was 6 volts using an analog meter, and didnt' seem to be going up. I
thought, Oh my gosh, I've run down my brand new battery, but when I
checked the voltage there, it was at least 12.5.

It should indeed be the battery voltage with no coil completing the
circuit. That would be troubling to me. Even if there's a dropping
resistor, with no current flowing except for the little the meter
needs, it should not be dropping voltage - so how's the other side?
This is two identical circuits - are both 6 volt?

The cap is .5 microfarads or so in a standard Kettering ignition - it
would charge instantaneously - in human terms.

If you measured it just after using it to heat the coil perhaps the
battery was 6 volts at that time? (they do recover when allowed to
rest, after a steep discharge)
BTW, how much damage *did* I do to the battery by running one ignition
coil for 2 to 2.5 hours?

Can't say. Was the battery hot? Did you put it on a slow charge
immediately after you discovered your mistake?

I lost my alternator on a trip and ran the bike until it wouldn't go
or turn the starter - I got it towed to my friends house and it sat
with a discharged battery for three days. I rigged some wire to her
car battery and when I got the alternator sorted out the battery was
still OK and started the bike.
3) On the other circuit, I tried to evaluate the other condenser by
turning the ignition off and measuring the resistance across the
points, which I'm pretty sure is across the condenser. I expected to
see the resistance pretty low as the condenser filled and then
increace. But the resistance was close to infinity. If I tested
right? that means the condensor is open, but that shouldn't keep the
cyclinder from firing, right? IIRC, mostly what it means is that the
points would pit quickly?? If I can't get the right condensor
quickly, what value and type would I need to jerry rig one
temporarily?

The condenser should read infinity - it charges too fast to see it
unless you were to use a high value series resistance and then watch
it charge through the resistor (the formula is resistance (in ohms)
times capacitance (in farads) to find the time constant - to reach
66.6% of full voltage). You have .0000005 farads and <1 ohms - that's
a half microsecond to charge - don't blink a blink is 1,000
microseconds.
4) There is a wick that lubricates the cam and keeps the rubbing
blocks from wearing out. I can't remember what I'm supposed to put on
the wick. What do I use, and if they don't still sell it, what do I
buy instead? :) (I had trouble remembering this 30 to 20 years ago,
too, but I haven't had to worry about it since I've had
all-elecctronic ignitions on my car)
They usually use something like a light grease worked into the felts.
Something like "Lubriplate" would be ideal - or just some 30 weight if
you aren't picky.
**If it had started, I would have remembered to turn the ignition off,
but since it didn't, I didn't. My fault.

BTW, the starter motor worked well, even though I hadn't checked it
out, and the kick starter seemed to maybe be working well, or at least
differently, even though it would go so far and then stop dead without
cranking up till now. The clutch disengaging is working fair, and the
throttle doesn't spring back quickly enough, even though I oiled all 3
cables (2 carburetors) and the throttle plates moved easily after
soaking the carburetors in Permatex.

I take a plastic bag and punch a hole in the bottom. Take the top of
the cable off the lever or twist grip and put it through the hole in
the bag. Use electrical tape to seal it well then just suspend it and
fill it with oil. Penetrating oil on very gummed up cables, but 30
weight is fine for most sluggish cables. The oil will eventually run
down through the cable sheath and free the cable.

Place in Canada has some good deals on coils and such for older bikes
(a fraction of list) www.partsnmore.com $35 minimum - but a coil
will cost you $30. Shipping free to the US. That's where I check
first for a part. Place called cycle recycle is also good.
 
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