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Discussion Starter · #1 ·
I've been asking around on chopcult for the last few months and the guys over there helped me out to get where I'm at but they said I might have better luck asking the guys over here on jockey journal.

So my mag is on a 72 shovelhead, kick only. I bought the joe hunt mag used last winter. Since then it got a new coil, points, and magnetized. I'm using solid copper core plug wires and non resistor plugs. Points and plug gap are at hints specs. When I bench test the mag on and anvil I get nice spark just be turning the mag by hand. However when I put it on the bike and kick it over while holding the plugs to the heads on and area I filed down to ensure a good connection the spark is very weak. And even stranger it's almost impossible to get spark off the rear cylinder when holding the plugs to it.

I've had the bike running a few times after I got the mag back from my mechanic who adjusted and filed the points but not long enough to ride it. But now she won't start at all.

Any ideas on my mag issue?
 

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If your mag doesn't have a Fairbanks Morse condenser I'd get one- if you got a new one from Hunt or Morris that's probably what you've got. Also a loose condenser hold down screw will cause serious problems/ burn points fast. Hold your points open/ look and make sure there's not a fresh pit in them. Make sure the 2 pinch bolts that hold the coil in are snug. When you get it sorted it will fire the motor every time. Testing the mag on the bike is pretty tough. You only get a half mag turn for every engine revolution. Pretty hard to see the spark, kick, at the same time. I think you're on the right track and close. 99% of my mag trouble (I've had 5 mag motors) has been points, condenser, or a mistake setting the timing.
 

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that's your problem right there is you asked a question on chop cult about a motorcycle. Half those guys don't know their asses from their elbows on that site,
This site is way more tech savy and is a group of guys with way more experience


okay now that we are passed that problem

Usually when magnetos have a hard time starting its a combination of one of these few things

-valve adjustment
-carb adjustment
-timing adjustment

I would advise ensuring that all of those are 100% spot on
pressure check your intake
clean your carb out, and I mean take it apart and give it a good thorough cleaning, and put it back to a baseline setting
ensure your valves are adjusted properly and not too tight

once you are certain those things are in proper order lets look at the magneto.

you state it gets good spark on the bench test but weak spark on the bike while kicking ?

what weight oil are you using ?
Ive had a lot of better results using 20w50 on mag fired bikes lately compared to straight 50w or 60w, simply being you get a little faster rotation on the flywheels while kicking when its cold with the 20w50 oil

what brand plug wires are you using ?
are you sure you have a solid connection ?

what type of hunt magneto is it ?
is it the horizontal magneto ?
if it is I had an awful experience with one where the hex drive was not indexed properly and it caused the same symptons you are describing good fat spark on the bench test, almost zero spark while kicking,
turns out the hex drive was way off and I needed to machine a new one to get it working properly.

also what condenser are you using ?
not all condensers are created equal check the above magneto sticky threads and read through the differences on them

how are you setting your timing on the magneto ?

give us some answers to the above and we can try and sort your problem out
 

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One more thought- all the guys I know that run mags stayed with/ fought them until they could keep them in good shape on their own- everybody that had someone else mess with them got ticked off and gave up.
 

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Discussion Starter · #5 ·
I had the valves adjusted, I didn't take the carb out or anything but the bike ran like a dream last season with electronic ignition. I set the carb to base settings though once I started running into trouble. It is a horizontal mag and I installed it. It's my first Harley but I followed the directions best I could while installing the hex drive but how can I tell of it's off? As far as the timing goes I'm getting the front cylinder at the top and putting the mag on where the small lobe is just about to open the points, I've had it running before setting it like this. I'm confident that the bike will run if I can get better spark (like getting while testing) when it's on the bike.

I have no idea what is on there for a condenser but I can get some pics of whatever you guys wanna see. And what do you mean by a "solid connection" everything between the mag and plugs is snug and tight.
 

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ya say you put the front piston to the top....was it on its compression stroke??? if it wasn't it'll never run right....has to be set with the front cylinder on its compression stroke.....
 

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Krause,
Just to make sure, are you referencing your front cylinder piston location by checking it just after the front intake valve closes?

Geo.
 

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So if it "ran like a dream", why did you fuck with it? Looking cool on the side of the road really isn't too cool...
Just sayin'
 

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Exhaust stroke has masqueraded as compression stroke before and frustrated many a man, so double check.

You can put a thumb over the plug hole to feel for the compression, or a rubber plug placed in the hole will pop out to let you know you're on the right stroke.
 

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^^^^^ This and make sure your cap connections are clean. If all this is right, swap plugs and wires and see if it still does it. If it does, look at the cap, if not or it switches to the front, look at the plug or wire.

I have a trouble shooting thread on here where I went through mine... The thing is, the used ones get taken off, thrown up on a shelf and sit there collecting dust and corrode. I know you don't want to hear this but, right now would be a good time to pull it back off and check the bearings in it before ya launch one and tear up more.
 

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Discussion Starter · #11 ·
As for checking the front cylinder I'm looking down the plug hole and watching the the piston to come up and after it comes up I turn it by hand until it gets to the top.
 

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Keep in mind it comes up TWICE for every revolution of the engine. Looking in the plug hole doesn't tell you squat...
 

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What everyone is getting at is that for every time the plug sparks the front piston comes up twice- once for compression/ spark. Second time for exhaust/ to clear the cylinder and start the process over (no spark) if you don't check with your thumb you only have a 50-50 chance that it's right- it can be exactly opposite. Put your thumb on the hole and kick till it puffs your thumb off- watch it the rest of the way to the top. Next check the point contacts for a little pit or mark/ spot on one face or the other- if there is a spot they need filed again. If no spot proceed. Turn the mag toward the little lobe until the points barely crack apart. Put in a brand new pair of plugs- not used ones, not cleaned ones- new ones. Turn the gas on and put the choke on full, crack the throttle about 1/8th turn and start kicking. If it doesn't bark in 8-10 kicks something's up. If it's still in the same shape it was when you hand spun it then it will run. Putting it on the bike won't change anything. Let us know what it does!! :)
 

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Also want to add that you are spinning the mag faster by hand on the bench than it spins on the bike whilst kicking.

I think that is what Carmine was inferring.
 

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I always pull the front intake pushrod tube and collapse. Rotate motor until the intake pushrod comes down, and about a half a turn later, the advance mark comes up. Just another way to find the correct stroke. To static time, I disconnect the wires from the points, including the condenser, and use a ohm meter to find the sweet spot(or the cracking of the points).
 

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i worked on a pan awhile back with a mag that was worked on by joe hunt twice (in one week). kicked on that thing for three days. it would spark then no spark. tried everything. put the old timer with points in it and gave it one courtesy kick and she fired right up.
i say get it running good with a timer then try the mag. if it don't fire up like the timer then something is wrong with that mag. what i don't know.i still have a love and hate relationship with magneatos.
 

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double check that the points plate and or rotor are for a ccw magneto. upright mags (pans/sportsters) rotate clockwise in operation. horizontal mags turn counter clockwise. sometimes used mags are made up of mis-matched parts. worth checking.
 

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I noticed in your original post you said a mechanic filed you points. You don't really dress those points with anything but a bisness card maybe a bis card dipped in thinner and then a clean dry one. Filing those points screws up a perfect factory surface. The only reason I mention this is because mag problems can be a combination of little problems or losses. Make sure the little springs that come out of the coil and touch the cap are clean and not rusty. Hunt says a timing light can damage the mag ;I have used a timing light on many mags without any damage.
 

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As for checking the front cylinder I'm looking down the plug hole and watching the the piston to come up and after it comes up I turn it by hand until it gets to the top.
That's what I was thinking.
By doing it that way you have a 50/50 chance of being on the right stroke, and if your luck is like mine . . . . . :).

Instead, use the method that Shovithead describes - observe the front intake lifter (the one towards the center, closest to the intake); as soon as it drops down (intake valve closes) you know that the cylinder has been charged and the piston is coming up towards the firing position. That is also the point when your timing mark on the flywheel will be coming into view through the inspection hole.

Geo.
 

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Discussion Starter · #20 ·
So today I got a chance to get to the shop and take a look. Bench tested it, tested it on the bike, made sure I was on compression stroke... etc. my spark is weak now even when testing, checked points and there isn't any real bad pitting or anything but I noticed a small blemish on the point surface. My points are deft growing off a spark when I'm turning the mag. I can see the spark when hand turning and I can really see it when I hook it up to a drill to turn faster. The spark is mainly white, slightly blue but it's a pretty big spark. The condenser is basically the only thing I haven't changed.

Thinking this may be why my bike ran a few times for a short time after the points were massaged. While the bike was running I'm thinking it messed my points up bc the condenser might be shit. And then that would make sense that I'm not having any luck with it now. Does that sound like it makes sense to you guys?
 
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