ignition coil
- Thread starter 5horsebriggs
- Start date
- Tags coil ignition
like 125ccCrazy said you can change the wire out . there is a small pin well more like a nail sticking up inside the coil where the wire goes in . and the wire is glued in the coil so take your time and dont break the pin off or dead coil . as for replacement wire you must use copper core or steel core will work too but thats old old school stuff . if you use the newer carbon wire it wont run at all .
funny story was at a shop back in ndak and one of the guys ask me what i know on magneto coils . well ... not to much but some stuff , why??
well i got this old hit and misser wont start every thing is good in it but it just wount fire got spark bla bla . so i take a look at it well pulled the plug wire off and used a jumpper lead out of the coil tower to ground and gave it a spin . snap snap snap big old fat spark .... hey herman ? its working now :shrug: well run it with a jumper and off she goes runs like its new . put the old wire on and dead . well what the ? cut the end off the wire here someone had put in a carbon wire . the old mags dont have the power to fire with that . so did some digging and got some copper core wire out and made new lead . hooked it up and gave it a turn pop pop pop off it goes . the guy had been looking it over for a year as to why it quit working never thought of the wire being the reason .
good places to find the old copper core is motorcycles shops may have a bulk roll ya can buy a few feet off .
mower shops may have something you could use Kohler used coppers i think
or tractor shops ask for the wire off a ford 8 n , 9n , 2 n they have them . at least in the 6 volt coils they do .
slim chance but a auto parts store mite have some but i wouldnt bet on it :shrug:
funny story was at a shop back in ndak and one of the guys ask me what i know on magneto coils . well ... not to much but some stuff , why??
well i got this old hit and misser wont start every thing is good in it but it just wount fire got spark bla bla . so i take a look at it well pulled the plug wire off and used a jumpper lead out of the coil tower to ground and gave it a spin . snap snap snap big old fat spark .... hey herman ? its working now :shrug: well run it with a jumper and off she goes runs like its new . put the old wire on and dead . well what the ? cut the end off the wire here someone had put in a carbon wire . the old mags dont have the power to fire with that . so did some digging and got some copper core wire out and made new lead . hooked it up and gave it a turn pop pop pop off it goes . the guy had been looking it over for a year as to why it quit working never thought of the wire being the reason .
good places to find the old copper core is motorcycles shops may have a bulk roll ya can buy a few feet off .
mower shops may have something you could use Kohler used coppers i think
or tractor shops ask for the wire off a ford 8 n , 9n , 2 n they have them . at least in the 6 volt coils they do .
slim chance but a auto parts store mite have some but i wouldnt bet on it :shrug:
Good Post! There are few that realize that a magneto should have solid core spark plug wire. And all our mini bike engines have magnetos. The other common mistake is to stop an engine by pulling the wire off the plug. The spark has to go somewhere and one handy place for the juice to ground is inside the coil between the high and low tension windings. A engine equipped with any magneto should never be turned over unless the high tension wire is grounded to the plug or elsewhere on the engine [or the ignition switch is off]. OK. It will probably not kill the coil right then and there. But a tiny carbon trail has been made by the spark inside the windings. As time goes by it can and will get worse. Missing at high speed or under load are symptoms. Then one day no spark at the plug at all!
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thanks oldsalt :thumbsup:
i have been doing alot of reading on old mag and coil systems like books from the 1800s on how they made them . im playing with a idea to make my own mag from a shaded pole motor , like what you find in the back of the fridge or in a microwave . theres a company that build kits like that called mini mag . there out of my skill level and price so im working on the cheap mans one .
doing the research on coils you learn alot on them . like a briggs coil has about 17 feet of primary winding and around 3500 feet of secondary winding . and the secondary wire is some dam small stuff like makes a hair look big . . giving you about 30,000 volts out put . what kills coils is when you spin the motor over and the coil fires you have 30,000 volts that wants to get to ground . now with no place to easily get there it back tracks in the secondary burning off the coating on the wire .
its strange that coils work at all given that the coating in them isnt able to handle the volts they make .
i have been doing alot of reading on old mag and coil systems like books from the 1800s on how they made them . im playing with a idea to make my own mag from a shaded pole motor , like what you find in the back of the fridge or in a microwave . theres a company that build kits like that called mini mag . there out of my skill level and price so im working on the cheap mans one .
doing the research on coils you learn alot on them . like a briggs coil has about 17 feet of primary winding and around 3500 feet of secondary winding . and the secondary wire is some dam small stuff like makes a hair look big . . giving you about 30,000 volts out put . what kills coils is when you spin the motor over and the coil fires you have 30,000 volts that wants to get to ground . now with no place to easily get there it back tracks in the secondary burning off the coating on the wire .
its strange that coils work at all given that the coating in them isnt able to handle the volts they make .
The big problem with the flywheel magnetos on our little motors is that the timing is not adjustable. The ignition system are designed to be OK for a pull starter to get them running without yanking the rope out of your hand but still with enough spark lead to allow them to run semi OK at 3600 RPM. The first attached pic is my bible for ignition for miniature engines. It even shows a design and plans for a approx. 1/4 scale magneto. But hell to build and not really suitable unless it is to be used on a 1/4 scale engine. I really believe the way to go is to rob a full sized Fairbanks-Morse mag off a big single cylinder motor. Remove the side case on a [for instance] Briggs motor and drill out the cam for a threaded extension. The side case would be bored out and a "O" ring groove provided for retention of oil. The cam extension would carry one of the 'belt sprockets' shown in the second pic. They are HTD type for the toothed timing belt shown. [Or put the belt sprocket on the engine output shaft and provide a belt sprocket with twice the number of teeth on the magneto]. The F-M magneto which would be mounted in front of the engine. It would he adjustable by rotation on its mount by a cable to a twist grip on the right handle bar. My prewar Knucklehead has the timing adjusted on the right grip and it works just fine unless a guy can't chew gum and walk at the same time. Crank it back for starting ...advance it as the RPMs go up. 12 to 1 compression ratio? No problem. I too have thought about the best way to do it and I think the above is the easiest. Alternately the stock flywheel could be removed or seriously altered to allow a belt sprocket to be used on the crank on that side and a belt sprocket with twice the number of teeth on the F-M magneto.
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bob shores book go figure :laugh:
he seems to have been the master at making small coils work . havent read his book but have seen some of the stuff he talked about in it .
using a mag off a motor would be a good way of doing it but some of the stuff im looking at the size wont work . would be like a tv hooked to a briggs block .
Model Engine Home Made 1936 Midget Magazine plans.wmv - YouTube
have the plans some place to build one of these . more shelf fodder but still fun to mess with and dream :shrug:
Falcon' Engineers Magneto Kit is what i was looking at doing a rip off copy of
Home of MiniMag Co.
. some of the main parts look like they could be easily made from the motors in microwaves and stuff . may never get built but something to mess with one day .
also falls under that stupid pride of look what i made work . would have been cheaper and easy to buy but i just had to do it myself .
its a strange thing i do ill build something just to see if i can make it work . even tho it has no real use its just something i have to build .
he seems to have been the master at making small coils work . havent read his book but have seen some of the stuff he talked about in it .
using a mag off a motor would be a good way of doing it but some of the stuff im looking at the size wont work . would be like a tv hooked to a briggs block .
Model Engine Home Made 1936 Midget Magazine plans.wmv - YouTube
have the plans some place to build one of these . more shelf fodder but still fun to mess with and dream :shrug:
Falcon' Engineers Magneto Kit is what i was looking at doing a rip off copy of
Home of MiniMag Co.
. some of the main parts look like they could be easily made from the motors in microwaves and stuff . may never get built but something to mess with one day .
also falls under that stupid pride of look what i made work . would have been cheaper and easy to buy but i just had to do it myself .
its a strange thing i do ill build something just to see if i can make it work . even tho it has no real use its just something i have to build .
You know Bob Shores!
The guy that made the 1936 magazine engine was pretty dedicated. Made his own patterns and then cast the parts and only then got to the machine work. I have five 1/4 scale engines in my little hobby machine shop at present. All were made using sets of castings produced by true model builders. All mine are 'hit and miss' types
I acquired the New Way engine in my avatar by trading a model for it. The pictured engine uses a Model T spark coil for ignition.
The guy that made the 1936 magazine engine was pretty dedicated. Made his own patterns and then cast the parts and only then got to the machine work. I have five 1/4 scale engines in my little hobby machine shop at present. All were made using sets of castings produced by true model builders. All mine are 'hit and miss' types
I acquired the New Way engine in my avatar by trading a model for it. The pictured engine uses a Model T spark coil for ignition.
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i know of bob shores . lots of people reference his book when talking about winding your own coils .
ya the 1936 magazine engine is a bit of a under taking . lots of little stuff and making the patterns then casting them .
no worse then some of the other stuff i have seen done . like motors built from steel plate and stock , and not little ones like 3 hp or more .
ya the 1936 magazine engine is a bit of a under taking . lots of little stuff and making the patterns then casting them .
no worse then some of the other stuff i have seen done . like motors built from steel plate and stock , and not little ones like 3 hp or more .
Hey guys, great information above. I'm a newbie to the forum and I think I have a similar issue. Recently purchased a 1974 Kawasaki KV75 in what I think is in great shape but unfortunately was in non-running condition at the time. The seller indicated it was runnign 2 weeks prior and then just died and was unable to start after that. Bottom line no spark. He suspected the points needed cleaning or replacing. I have not tried that as yet mostly because I don't have the proper flywheel pulling tool, but going to try clean them on the weekend through the gap in the flywheel. That being said when examing the plug (I replaced just in case) the spark plug cap came off the lead with very little effort. I clipped the lead back by about 1/4" and rethreaded the cap back on but with no success.
I have the online FSM which has a good troubleshooting guide
http://sundry.tech.purdue.edu/mleasure/Personal/KV75-Service-Manual.pdf
and it leads me to believe I may have a bad ignition coil. I put my multimeter across the coil and could not verify the specified resistance (supposed to be 2.41 - 2.81 ohms across the primary and 10 ohms across the secondary). In fact I had a hard time getting it to read consistenty at all, but most often got 0.9 ohms across the primary coil.
Anyway, my question is where can I find a replacement ignition coil? I've searched exhaustively on the net and have not been able to find anything remotely clost to what I have on the bike. One site that says it has coils for the KV75 is JCWhitney but again, the product it shows looks nothing like what I have. I'd call them up but being in Australia it is a little tough. Are there modern aftermarket alternatives to the original that you are aware of? I would love to get this little beast up and running. If not the coil or the points, then the FSM suggests the magneto next. Really hoping that is not the issue.
Any help you guys can give is appreciated.
I have the online FSM which has a good troubleshooting guide
http://sundry.tech.purdue.edu/mleasure/Personal/KV75-Service-Manual.pdf
and it leads me to believe I may have a bad ignition coil. I put my multimeter across the coil and could not verify the specified resistance (supposed to be 2.41 - 2.81 ohms across the primary and 10 ohms across the secondary). In fact I had a hard time getting it to read consistenty at all, but most often got 0.9 ohms across the primary coil.
Anyway, my question is where can I find a replacement ignition coil? I've searched exhaustively on the net and have not been able to find anything remotely clost to what I have on the bike. One site that says it has coils for the KV75 is JCWhitney but again, the product it shows looks nothing like what I have. I'd call them up but being in Australia it is a little tough. Are there modern aftermarket alternatives to the original that you are aware of? I would love to get this little beast up and running. If not the coil or the points, then the FSM suggests the magneto next. Really hoping that is not the issue.
Any help you guys can give is appreciated.