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OT ~ perhaps, advice on ignition system

D

default

Jan 1, 1970
0
My '81 Honda motorcycle dies in the rain.

Obvious choices are the HV ignition system.

Motorcycle will do fine with just a replacement gas tank - 32 ounce
soldered tin can. But I haven't tried that in the rain - I have to
wait for rain . . .

Motorcycle will work fine as long as the weather is dry. Duh?

Motorcycle will work for "any" amount of time with just the trial gas
tank - and water being sprayed over the ignition system - from fine
spray to jet spray

MC is a Honda '81 with a transistor switch ignition. The pickup coil
drives a TX switch. Coils are tied to B+ on one side.

I tried dumping a bucket (5 quarts) of water on the ignition
coils/wires/plugs while idling - no change in idle speed.

MC dies when in rain only, after about 5-20 minutes. MC will work as
long as there is no rain (hundreds of miles). MC will start after a
pause - and run for a time, after wet, dependent on rest period and
rain level. Will always start when wet - but won't go.

Two completely independent ignition systems - firing two coils.
Pickup coils detect the fire timing and transfer that to two coils and
ground them for the dwell time. Coils are three ohms. The reverse EMF
on the coils is ~200 volts.

Obviously I am over looking something

HELP!
 
M

martin griffith

Jan 1, 1970
0
My '81 Honda motorcycle dies in the rain.

Obvious choices are the HV ignition system.

Motorcycle will do fine with just a replacement gas tank - 32 ounce
soldered tin can. But I haven't tried that in the rain - I have to
wait for rain . . .

Motorcycle will work fine as long as the weather is dry. Duh?

Motorcycle will work for "any" amount of time with just the trial gas
tank - and water being sprayed over the ignition system - from fine
spray to jet spray

MC is a Honda '81 with a transistor switch ignition. The pickup coil
drives a TX switch. Coils are tied to B+ on one side.

I tried dumping a bucket (5 quarts) of water on the ignition
coils/wires/plugs while idling - no change in idle speed.

MC dies when in rain only, after about 5-20 minutes. MC will work as
long as there is no rain (hundreds of miles). MC will start after a
pause - and run for a time, after wet, dependent on rest period and
rain level. Will always start when wet - but won't go.

Two completely independent ignition systems - firing two coils.
Pickup coils detect the fire timing and transfer that to two coils and
ground them for the dwell time. Coils are three ohms. The reverse EMF
on the coils is ~200 volts.

Obviously I am over looking something

HELP!
1) You are lucky that you don't have to deal with '70s Ducati
electrics.....

2)Since you appear to have 2 independent systems, maybe there is a
problem on the DC source side, is it electronically switched?

3) Run the MC in the dark, and lookout for corona, but that's a long
shot.


martin
 
D

default

Jan 1, 1970
0
2)Since you appear to have 2 independent systems, maybe there is a
problem on the DC source side, is it electronically switched?
I haven't ruled out the LV side of things. The two systems don't fail
exactly coincident with each other - one will go and the bike will
stagger on for a few seconds then the other goes out.

The Clymer manual calls it a CDI ignition system, but it is only
supplied with 12 volts and the switching modules are only ~1 cubic
inch - I doubt they had any real CDI system back then (and that
small?) Modules are large enough for a power transistor or two and a
cap.
3) Run the MC in the dark, and lookout for corona, but that's a long
shot.
I'll give that a try - I'm grasping at straws now.

I did break down and replaced the plug connectors and wires - that has
really made a difference in acceleration and idling so maybe that is
it . . . The old plug caps measured between 6-9 K ohm resistance and
all the new ones are exactly 5 K (5K is what it should be).

I've had a few bikes with some pretty horrible electrics - a Gilera in
~'66 and Triumph in '70. Gilera - the engine would die if the stop
light was blown out and you braked, side draft carb float would cause
it to accelerate in left hand turns and slow in right turns - Trumpet
caps would die and the engine would make a burbling sound when
accelerating. Neither had headlights worth a damn. Neither bike was
much good above 8,000 feet in altitude.
 
M

martin griffith

Jan 1, 1970
0
On Fri, 27 Apr 2007 16:25:29 +0200, martin griffith

I've had a few bikes with some pretty horrible electrics - a Gilera in
~'66 and Triumph in '70. Gilera - the engine would die if the stop
light was blown out and you braked, side draft carb float would cause
it to accelerate in left hand turns and slow in right turns - Trumpet
caps would die and the engine would make a burbling sound when
accelerating. Neither had headlights worth a damn. Neither bike was
much good above 8,000 feet in altitude.

Argh, I rememer dirtbiking just after new year, in the snow in
Derbyshire on a Montesa, and the magneto packed up. It wasn't even
Lucas, I was towed 8 Km across the rough, including a river bed, in
the dark. Not fun


martin
 
E

ehsjr

Jan 1, 1970
0
default said:
My '81 Honda motorcycle dies in the rain.

Obvious choices are the HV ignition system.

Motorcycle will do fine with just a replacement gas tank - 32 ounce
soldered tin can. But I haven't tried that in the rain - I have to
wait for rain . . .

Motorcycle will work fine as long as the weather is dry. Duh?

Motorcycle will work for "any" amount of time with just the trial gas
tank - and water being sprayed over the ignition system - from fine
spray to jet spray

MC is a Honda '81 with a transistor switch ignition. The pickup coil
drives a TX switch. Coils are tied to B+ on one side.

I tried dumping a bucket (5 quarts) of water on the ignition
coils/wires/plugs while idling - no change in idle speed.

MC dies when in rain only, after about 5-20 minutes. MC will work as
long as there is no rain (hundreds of miles). MC will start after a
pause - and run for a time, after wet, dependent on rest period and
rain level. Will always start when wet - but won't go.

Two completely independent ignition systems - firing two coils.
Pickup coils detect the fire timing and transfer that to two coils and
ground them for the dwell time. Coils are three ohms. The reverse EMF
on the coils is ~200 volts.

Obviously I am over looking something

HELP!

Maybe not an electronic problem?
Some kind of vaporlock in the fuel system
piping comes to mind as a possibility.

Ed
 
D

default

Jan 1, 1970
0
Maybe not an electronic problem?
Some kind of vaporlock in the fuel system
piping comes to mind as a possibility.

Ed

The temperature may drop a little in rain if anything.

I did consider a fuel problem - sprayed water on the seals between the
carbs and cylinders so it isn't sucking some water in there. Runs a
little lean, but I haven't re jetted since replacing the exhaust.

Possible that the water on the fuel cap is making the tank vapor
tight. There's a large rubber washer that is spring loaded to press
against the tank opening. It must be a perfect seal it always looks
like polished steel - no rust. Possible that a tiny amount of water
is just viscous enough completely seal the tank and it tries to pull a
vacuum - that would account for all the symptoms - and something I
should be able to check with a water bottle and some driving.

There are four carbs one for each cylinder - I wouldn't expect them
all to drop out together - but this isn't like running out of gas,
there's always a little in the tank that sloshes into the fuel tube -
a vacuum would mean no carb gets a taste of gas once the vacuum forms.
Rain cooling the tank would also lower the vapor pressure. (and it
fits all the other symptoms very well)

one more thing to try . . .
 
R

Rich Grise

Jan 1, 1970
0
The temperature may drop a little in rain if anything.

I did consider a fuel problem - sprayed water on the seals between the
carbs and cylinders so it isn't sucking some water in there. Runs a
little lean, but I haven't re jetted since replacing the exhaust.

Possible that the water on the fuel cap is making the tank vapor
tight. There's a large rubber washer that is spring loaded to press
against the tank opening. It must be a perfect seal it always looks
like polished steel - no rust. Possible that a tiny amount of water
is just viscous enough completely seal the tank and it tries to pull a
vacuum - that would account for all the symptoms - and something I
should be able to check with a water bottle and some driving.

There are four carbs one for each cylinder - I wouldn't expect them
all to drop out together - but this isn't like running out of gas,
there's always a little in the tank that sloshes into the fuel tube -
a vacuum would mean no carb gets a taste of gas once the vacuum forms.
Rain cooling the tank would also lower the vapor pressure. (and it
fits all the other symptoms very well)

one more thing to try . . .

Is the air filter getting wet and plugging up the intake?

Good Luck!
Rich
 
D

default

Jan 1, 1970
0
Is the air filter getting wet and plugging up the intake?

Good Luck!
Rich
Unlikely. Air box opening faces aft and has no leaks. It will
tolerate a lot of sprayed water before it starts running rough. I
sprayed water everywhere even the places that shouldn't cause problems
- fuse box, headlight nacelle, anywhere wires run or air moves.

The symptoms when it dies are rather sudden - just like switching off
the ignition. I sometimes lose one pair of cylinders first then the
other. Each (brand new) ignition coil feeds two cylinders - one spark
is wasted firing a cylinder that is not on the compression stroke.

The coil side has compression ferrules,of rubber, that grip and
waterproof the HV wire. The plug caps only have rubber boots - but
have worked well enough in the past.

When I replaced the caps and wire I used some thick silicone grease
that is supposed to be for "spark plug boot release."

Maybe there's more than one cause for the problem. Maybe I should be
dealing with the lean running . . . that and a weak spark, high
moisture in the air . . .

Dies just like switching off the ignition so that's where I'm
concentrating.
 
J

Jim Thompson

Jan 1, 1970
0
Unlikely. Air box opening faces aft and has no leaks. It will
tolerate a lot of sprayed water before it starts running rough. I
sprayed water everywhere even the places that shouldn't cause problems
- fuse box, headlight nacelle, anywhere wires run or air moves.

The symptoms when it dies are rather sudden - just like switching off
the ignition. I sometimes lose one pair of cylinders first then the
other. Each (brand new) ignition coil feeds two cylinders - one spark
is wasted firing a cylinder that is not on the compression stroke.

The coil side has compression ferrules,of rubber, that grip and
waterproof the HV wire. The plug caps only have rubber boots - but
have worked well enough in the past.

When I replaced the caps and wire I used some thick silicone grease
that is supposed to be for "spark plug boot release."

Maybe there's more than one cause for the problem. Maybe I should be
dealing with the lean running . . . that and a weak spark, high
moisture in the air . . .

Dies just like switching off the ignition so that's where I'm
concentrating.

I'm late to the discussion, so this may be a repeated question...

Electronic ignition? I've had those modules in the distributor fail
with the symptom of like you just momentarily just turned it off.

Particularly Fords... which I placed on my "Do Not Purchase" list
almost exactly 30 years ago... scary as hell, tooting down the
freeway, suddenly no power, slows then resumes ignition :-(

...Jim Thompson
 
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