Forums

Major Differences In Small Engine Coils

Started by Bret Cahill April 26, 2012
Maybe the voltages vary somewhat for different point and plug gaps but
is it enough to make any difference?  .

Supposedly Honda no longer makes the coils for their 100 outboard, a 2
cylinder 4 stroke engine.  Isn't it likely that other small engines,
say from riding lawnmowers, use coils that are pretty much the same?

For that matter couldn't a motor vehicle coil work?


Bret Cahill


On Thu, 26 Apr 2012 04:11:38 -0700 (PDT), Bret Cahill
<Bret_E_Cahill@yahoo.com> wrote:

>Maybe the voltages vary somewhat for different point and plug gaps but >is it enough to make any difference? . > >Supposedly Honda no longer makes the coils for their 100 outboard, a 2 >cylinder 4 stroke engine. Isn't it likely that other small engines, >say from riding lawnmowers, use coils that are pretty much the same? > >For that matter couldn't a motor vehicle coil work? > > >Bret Cahill >
I wouldn't jump to that conclusion without doing some poking around. Does it use a separate coil or is it a magneto mounted on the flywheel? Does it use a transistor switched coil high turns ration pulse transformer or inductive kick type? There's also something called "energy transfer magneto" which is a low voltage coil and points mounted on the engine, feeding a more or less regular ignition coil. There is bound to be some way to kludge something that will work once you know what kind of system it uses.
> >Maybe the voltages vary somewhat for different point and plug gaps but > >is it enough to make any difference? =A0. > > >Supposedly Honda no longer makes the coils for their 100 outboard, a 2 > >cylinder 4 stroke engine. =A0Isn't it likely that other small engines, > >say from riding lawnmowers, use coils that are pretty much the same? > > >For that matter couldn't a motor vehicle coil work? > > >Bret Cahill > > I wouldn't jump to that conclusion without doing some poking around. > > Does it use a separate coil or is it a magneto mounted on the > flywheel? =A0Does it use a transistor switched coil high turns ration > pulse transformer or inductive kick type? > > There's also something called "energy transfer magneto" which is a low > voltage coil and points mounted on the engine, feeding a more or less > regular ignition coil.
That sounds like it.
> There is bound to be some way to kludge something that will work once > you know what kind of system it uses.
Actually the part may have been discontinued for the very reason that the later coils may be easily substituted. This isn't even an opportunity to jerry rig something together. Bret Cahill
"Bret Cahill" <Bret_E_Cahill@yahoo.com> wrote in message 
news:b710b382-f457-4e20-a73c-871f31178112@f37g2000yqc.googlegroups.com...
> >Maybe the voltages vary somewhat for different point and plug gaps but > >is it enough to make any difference? . > > >Supposedly Honda no longer makes the coils for their 100 outboard, a 2 > >cylinder 4 stroke engine. Isn't it likely that other small engines, > >say from riding lawnmowers, use coils that are pretty much the same? > > >For that matter couldn't a motor vehicle coil work? > > >Bret Cahill > > I wouldn't jump to that conclusion without doing some poking around. > > Does it use a separate coil or is it a magneto mounted on the > flywheel? Does it use a transistor switched coil high turns ration > pulse transformer or inductive kick type? > > There's also something called "energy transfer magneto" which is a low > voltage coil and points mounted on the engine, feeding a more or less > regular ignition coil.
That sounds like it.
> There is bound to be some way to kludge something that will work once > you know what kind of system it uses.
Actually the part may have been discontinued for the very reason that the later coils may be easily substituted. This isn't even an opportunity to jerry rig something together. Bret Cahill ---------------------------------------------------- Since theOP mentions plug gap; its obviously not using surface discharge plugs (common on marine engines) - they would definately indicate CDI, so there's some hope they're "regular" coils with points or a TAC module. Probably worth giving motorcycle coils a try - these come in the 2-lead (wasted spark) variety used on 4's & some twins, or a pair of single lead coils as used on twins with 180deg crankshaft.
"Bret Cahill" <Bret_E_Cahill@yahoo.com> wrote in message 
news:1ac4aabe-c61d-49b4-ab3e-bb52cd0e0b31@hq4g2000vbb.googlegroups.com...
>> > >Maybe the voltages vary somewhat for different point and plug gaps but >> > >is it enough to make any difference? . >> >> > >Supposedly Honda no longer makes the coils for their 100 outboard, a 2 >> > >cylinder 4 stroke engine. Isn't it likely that other small engines, >> > >say from riding lawnmowers, use coils that are pretty much the same? >> >> > >For that matter couldn't a motor vehicle coil work? >> >> > >Bret Cahill >> >> > I wouldn't jump to that conclusion without doing some poking around. >> >> > Does it use a separate coil or is it a magneto mounted on the >> > flywheel? Does it use a transistor switched coil high turns ration >> > pulse transformer or inductive kick type? >> >> > There's also something called "energy transfer magneto" which is a low >> > voltage coil and points mounted on the engine, feeding a more or less >> > regular ignition coil. >> >> That sounds like it. >> >> > There is bound to be some way to kludge something that will work once >> > you know what kind of system it uses. >> >> Actually the part may have been discontinued for the very reason that >> the later coils may be easily substituted. >> >> This isn't even an opportunity to jerry rig something together. >> >> Bret Cahill >> >> ---------------------------------------------------- >> >> Since theOP mentions plug gap; its obviously not using surface discharge >> plugs (common on marine engines) - they would definately indicate CDI, so >> there's some hope they're "regular" coils with points or a TAC module. >> >> Probably worth giving motorcycle coils a try - these come in the 2-lead >> (wasted spark) variety used on 4's & some twins, or a pair of single lead >> coils as used on twins with 180deg crankshaft. > > Now they are claiming it was a "rectifier" not a coil. > > What would a rectifier do on any ignition system? > > > Bret Cahill
On a CDI there would be a rectifier between the transistor inverter and the capacitor, some engines have a high voltage winding on the alternator/generator stator - but either way the CDI is usually a sealed unit, so I don't know how exactly they could determine that specifically the rectifier was at fault. I did once encounter a Yamaha 125 with energy transfer ignition that had a diode in the lead from the flywheel coil & ignition coil - failure of that diode probably would have impaired performance but not stopped it running altogether. Maybe if you could post photos of the equipment on a hosting site, and the link to it here, someone might recognise it and supply some informed advice.
> >> > >Maybe the voltages vary somewhat for different point and plug gaps but > >> > >is it enough to make any difference? . > > >> > >Supposedly Honda no longer makes the coils for their 100 outboard, a 2 > >> > >cylinder 4 stroke engine. Isn't it likely that other small engines, > >> > >say from riding lawnmowers, use coils that are pretty much the same? > > >> > >For that matter couldn't a motor vehicle coil work? > > >> > >Bret Cahill > > >> > I wouldn't jump to that conclusion without doing some poking around. > > >> > Does it use a separate coil or is it a magneto mounted on the > >> > flywheel? Does it use a transistor switched coil high turns ration > >> > pulse transformer or inductive kick type? > > >> > There's also something called "energy transfer magneto" which is a low > >> > voltage coil and points mounted on the engine, feeding a more or less > >> > regular ignition coil. > > >> That sounds like it. > > >> > There is bound to be some way to kludge something that will work once > >> > you know what kind of system it uses. > > >> Actually the part may have been discontinued for the very reason that > >> the later coils may be easily substituted. > > >> This isn't even an opportunity to jerry rig something together. > > >> Bret Cahill > > >> ---------------------------------------------------- > > >> Since theOP mentions plug gap; its obviously not using surface discharge > >> plugs (common on marine engines) - they would definately indicate CDI, so > >> there's some hope they're "regular" coils with points or a TAC module. > > >> Probably worth giving motorcycle coils a try - these come in the 2-lead > >> (wasted spark) variety used on 4's & some twins, or a pair of single lead > >> coils as used on twins with 180deg crankshaft. > > > Now they are claiming it was a "rectifier" not a coil. > > > What would a rectifier do on any ignition system? > > > Bret Cahill > > On a CDI there would be a rectifier between the transistor inverter and the > capacitor, some engines have a high voltage winding on the > alternator/generator stator - but either way the CDI is usually a sealed > unit, so I don't know how exactly they could determine that specifically the > rectifier was at fault.
This was just another flywheel magneto/alternator to charge up a battery to power running lights, about 60 watts, completely independent of the ignition system.
> I did once encounter a Yamaha 125 with energy transfer ignition that had a > diode in the lead from the flywheel coil & ignition coil - failure of that > diode probably would have impaired performance but not stopped it running > altogether. > > Maybe if you could post photos of the equipment on a hosting site, and the > link to it here, someone might recognise it and supply some informed advice.-
http://data.sohc4.net/Tech/HondaMES/HondaMES5.PDF The first time I saw the 1978 BF100 outboard was wired up like the system of Fig 48. I'm not 100% sure, however, the original system wasn't the low tension magneto system of Fig. 47 and a shop / previous owner confused the two systems and wired the point/cap wire to the same connector as the magneto output by mistake. The top of the new coil is mounted to the engine by a bolt going through the center lug and then through a laminated 1 cm^3 cube that looks like it could be an insulator. That would explain how the magneto could put out a few volts on an analog multimeter yet the secondary puts out nothing. The primary coil never has any way to complete a circuit. That's one easy to test theory. On the other hand the system would be correctly wired up but since the original coil was discontinued the new coil could be for different system. The 1 cm^3 cube is in fact an insulator that prevents the primary from being grounded. (I'm good at coming up with a multitude of theories, not all suspect, when trouble shooting.) I get ball park range resistances for the coil, 0.75, 3 and 30,000 ohms between the 2 ark plug wires. By tapping the condenser with 12 volts DC at 2 - 3 hz the volt meter goesp more than tapping w/o the cap. I like to try the easy stuff first so I won't worry about the coil and cap just yet. There are still other easy problems to be checked, i.e., shorts and broken wires, bad kill button, points open to 0.017 which is a little high compared to some systems. Maybe lower that to 0.014 to make sure it is closed some of the time. Bret Cahill
"Bret Cahill" <BretCahill@peoplepc.com> wrote in message 
news:1893cb53-0786-4279-9099-5373d4461910@n8g2000pbv.googlegroups.com...
>> >> > >Maybe the voltages vary somewhat for different point and plug gaps >> >> > >but >> >> > >is it enough to make any difference? . >> >> >> > >Supposedly Honda no longer makes the coils for their 100 outboard, >> >> > >a 2 >> >> > >cylinder 4 stroke engine. Isn't it likely that other small engines, >> >> > >say from riding lawnmowers, use coils that are pretty much the >> >> > >same? >> >> >> > >For that matter couldn't a motor vehicle coil work? >> >> >> > >Bret Cahill >> >> >> > I wouldn't jump to that conclusion without doing some poking around. >> >> >> > Does it use a separate coil or is it a magneto mounted on the >> >> > flywheel? Does it use a transistor switched coil high turns ration >> >> > pulse transformer or inductive kick type? >> >> >> > There's also something called "energy transfer magneto" which is a >> >> > low >> >> > voltage coil and points mounted on the engine, feeding a more or >> >> > less >> >> > regular ignition coil. >> >> >> That sounds like it. >> >> >> > There is bound to be some way to kludge something that will work >> >> > once >> >> > you know what kind of system it uses. >> >> >> Actually the part may have been discontinued for the very reason that >> >> the later coils may be easily substituted. >> >> >> This isn't even an opportunity to jerry rig something together. >> >> >> Bret Cahill >> >> >> ---------------------------------------------------- >> >> >> Since theOP mentions plug gap; its obviously not using surface >> >> discharge >> >> plugs (common on marine engines) - they would definately indicate CDI, >> >> so >> >> there's some hope they're "regular" coils with points or a TAC module. >> >> >> Probably worth giving motorcycle coils a try - these come in the >> >> 2-lead >> >> (wasted spark) variety used on 4's & some twins, or a pair of single >> >> lead >> >> coils as used on twins with 180deg crankshaft. >> >> > Now they are claiming it was a "rectifier" not a coil. >> >> > What would a rectifier do on any ignition system? >> >> > Bret Cahill >> >> On a CDI there would be a rectifier between the transistor inverter and >> the >> capacitor, some engines have a high voltage winding on the >> alternator/generator stator - but either way the CDI is usually a sealed >> unit, so I don't know how exactly they could determine that specifically >> the >> rectifier was at fault. > > This was just another flywheel magneto/alternator to charge up a > battery to power running lights, about 60 watts, completely > independent of the ignition system. > >> I did once encounter a Yamaha 125 with energy transfer ignition that had >> a >> diode in the lead from the flywheel coil & ignition coil - failure of >> that >> diode probably would have impaired performance but not stopped it running >> altogether. >> >> Maybe if you could post photos of the equipment on a hosting site, and >> the >> link to it here, someone might recognise it and supply some informed >> advice.- > > http://data.sohc4.net/Tech/HondaMES/HondaMES5.PDF > > The first time I saw the 1978 BF100 outboard was wired up like the > system of Fig 48.
If it is the coil you need, a lot of small motorcycles use the energy transfer type. CDI has probably become more common on modern models, but for 80's models most small 2-strokes used energy transfer and some small 4-strokes like the Honda C50 & C70 step-through's (the C90 had Kettering battery-coil ign). Another group you might find some help on is sci.electronics.repair - strictly its for electronic equipment, but there's plenty of knowlegeable people there.
> >> >> > >Maybe the voltages vary somewhat for different point and plug ga=
ps
> >> >> > >but > >> >> > >is it enough to make any difference? . > > >> >> > >Supposedly Honda no longer makes the coils for their 100 outboar=
d,
> >> >> > >a 2 > >> >> > >cylinder 4 stroke engine. Isn't it likely that other small engin=
es,
> >> >> > >say from riding lawnmowers, use coils that are pretty much the > >> >> > >same? > > >> >> > >For that matter couldn't a motor vehicle coil work? > > >> >> > >Bret Cahill > > >> >> > I wouldn't jump to that conclusion without doing some poking arou=
nd.
> > >> >> > Does it use a separate coil or is it a magneto mounted on the > >> >> > flywheel? Does it use a transistor switched coil high turns ratio=
n
> >> >> > pulse transformer or inductive kick type? > > >> >> > There's also something called "energy transfer magneto" which is =
a
> >> >> > low > >> >> > voltage coil and points mounted on the engine, feeding a more or > >> >> > less > >> >> > regular ignition coil. > > >> >> That sounds like it. > > >> >> > There is bound to be some way to kludge something that will work > >> >> > once > >> >> > you know what kind of system it uses. > > >> >> Actually the part may have been discontinued for the very reason th=
at
> >> >> the later coils may be easily substituted. > > >> >> This isn't even an opportunity to jerry rig something together. > > >> >> Bret Cahill > > >> >> ---------------------------------------------------- > > >> >> Since theOP mentions plug gap; its obviously not using surface > >> >> discharge > >> >> plugs (common on marine engines) - they would definately indicate C=
DI,
> >> >> so > >> >> there's some hope they're "regular" coils with points or a TAC modu=
le.
> > >> >> Probably worth giving motorcycle coils a try - these come in the > >> >> 2-lead > >> >> (wasted spark) variety used on 4's & some twins, or a pair of singl=
e
> >> >> lead > >> >> coils as used on twins with 180deg crankshaft. > > >> > Now they are claiming it was a "rectifier" not a coil. > > >> > What would a rectifier do on any ignition system? > > >> > Bret Cahill > > >> On a CDI there would be a rectifier between the transistor inverter an=
d
> >> the > >> capacitor, some engines have a high voltage winding on the > >> alternator/generator stator - but either way the CDI is usually a seal=
ed
> >> unit, so I don't know how exactly they could determine that specifical=
ly
> >> the > >> rectifier was at fault. > > > This was just another flywheel magneto/alternator to charge up a > > battery to power running lights, about 60 watts, completely > > independent of the ignition system. > > >> I did once encounter a Yamaha 125 with energy transfer ignition that h=
ad
> >> a > >> diode in the lead from the flywheel coil & ignition coil - failure of > >> that > >> diode probably would have impaired performance but not stopped it runn=
ing
> >> altogether. > > >> Maybe if you could post photos of the equipment on a hosting site, and > >> the > >> link to it here, someone might recognise it and supply some informed > >> advice.- > > >http://data.sohc4.net/Tech/HondaMES/HondaMES5.PDF > > > The first time I saw the 1978 BF100 outboard =A0was wired up like the > > system of Fig 48. > > If it is the coil you need, a lot of small motorcycles use the energy > transfer type. > > CDI has probably become more common on modern models, but for 80's models > most small 2-strokes used energy transfer and some small 4-strokes like t=
he
> Honda C50 & C70 step-through's (the C90 had Kettering battery-coil ign). > > Another group you might find some help on is sci.electronics.repair - > strictly its for electronic equipment, but there's plenty of knowlegeable > people there.
Thanks. Bret Cahill