Magneto replacement?

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
I was wondering if any of you knowledgeable bike builder types know if there is a guide to replacing the magneto. I was riding in the rain the other day and my magneto got wet; and lo and behold there was no spark. Can it be rebuilt? Will drying it off save it? Does the magnet have to be in a particular position in it's rotation in relation to the coil in order to fire properly? Thanks in advance.
 

misteright1_99

New Member
Mar 21, 2008
716
0
0
Treasure Coast, Florida
Drying it off might fix it, if getting wet didnt fry the CDI. I read somehwere that you just unbolt it from the two mounting points, then when placing the new one in wrap something like a business card around the magnet, till it is mounted, then remove the card. I imagine this helps with centering the magnet.
 

Dave31

Moderator
Staff member
Mar 1, 2008
11,204
29
38
Aztlán, Arizona
Spray it with some WD-40 and give it a try....if you are lucky nothing got smoked.

To remove the mag, just unscrew the four bolts. To re-install it, start with one bolt, then another and so on. Do not tighten them until you have all the bolts in. Just a little wiggling will get the job done.
 

jasonh

New Member
Jun 23, 2008
1,590
0
0
36
Longmont, CO
You can also bake it in the oven for a bit to cook off some of that moisture inside. 250 degrees maybe for 10 min or so. Worth a shot.

It's probably dead though.
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
68
pampa texas
or until its a light golden brown.rotfl
Gee I wish the old snake would make some cholate chip cookies that made me hungry.:crash:
 

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
Well i tried all those things... my magneto is now a nice golden brown caramelized glaze on the outside. And I still have no spark.

I'm thinking its got to be either the mag or the CDI. How do I figure out which one failed? I do have a multi-meter - i just don't know how to test and what to look for.

Any suggestions?
 

lylespen

New Member
Dec 16, 2008
1
0
0
Saint Augustine FL
Hi-new member, been lurking for a few weeks, learning a lot from very valuable site, as I complete first Bikeberry Raw kit. Have common "no spark" problem--wiring appears to be correct, dry, stop switch disconnected, plug out, no spark as spin mag. I see thread references to a table of multimeter troubleshooting readings: cdi expected ohm resistance, mag and cdi expected voltage when spun, but can't find it. Would GREATLY appreciate URL ref.

And one minor contribution re. engine, cdi, cutoff switch wiring heat and other damage protection: use 3/4 in. flexible aluminum electrical conduit (mine left over from hot water heater installation, conduit required by FL building code). Thanks
 

jasonh

New Member
Jun 23, 2008
1,590
0
0
36
Longmont, CO
Code:
CDI pack GOOD 
Black to Blue 1150kΩ 
Black to Plug 2.6kΩ 
Blue to Plug 1150kΩ 


Magneto
Blue to White 327Ω 
Black to Blue 327Ω 
Black to White 2.1Ω 
Black to Gnd 0Ω 
Blue to Gnd 327Ω 
White to Gnd 2.1Ω
 
Sep 20, 2008
1,668
2
0
Clearwater, FL
web.tampabay.rr.com
nerevar,

It is highly unlikely that the Mag was affected by a little water. If it got submerged maybe...but if it was a little damp I doubt it. They aren't that delicate. The CDI is. I suppose if the wire connectors got really wet the CDI may have shorted and popped one of the IC's. If you find that the mag coil is bad, I would attribute it to coincidence as opposed to a little water.

Are you using the original bullet connectors that connect the mag to the CDI? They are so crappy that they can appear to be well connected when actualy they're not.

If your Ohm readings are correct per Jasons' post try crimping on some new connectors. Also change the plug and plug wire...it's cheap and easy to do.

Jim
 

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
I already replaced the plug and plug wire, so that's not it. I also crimped down the connectors between the mag and CDI to make sure there was a good connection, so I don't think that's it either. I'm thinking it's the CDI, but before I order a new one I need direction on how to actually test the CDI and mag. What I mean is where do I put each lead of the multimeter, and do I need to crank the engine for it to give me readings? Thanks in advance guys.
 

2door

Moderator
Staff member
Sep 15, 2008
16,326
124
63
Littleton, Colorado
Your meter leads go where Jason's directions say. Example: One lead will go to the blue wire and the other lead to the black wire. You should read approx. 1150 K on your meter scale.
The engine does not need to be running but all the leads, (wires) need to be disconnected from each other. You're reading resistance, not voltage. Your meter needs to be set to read ohms, not volts or amps.
Is your meter digital or analog? Doesn't make any difference except an analog scale is a little more difficult to read if you're not familiar with it.
Tom
 
Last edited:

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
I just got the readings, and they're way off for both the CDI and mag. All the readings concerning the blue wire on the mag come out open, and the blue wire readings on the CDI are in the 2.6 Meg ohm range. I think I have to order both a CDI and mag.
Know where I can get both that will work well together?
 

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
hey this is a little off topic, but I forgot to put fuel stabilizer in the fuel before the off season set in... Is this a really bad thing? Will I have to toss the old fuel?
 

Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
I just ordered the parts from thatsdax.com. Except they were sold out of magneto cover gaskets. Where can I get one or should I just make my own? Any ideas?
 

tdecker

New Member
Apr 11, 2017
1
0
0
Savannah, GA
I just had a problem with my magneto as well. I had parked my bike just before a storm rolled through. It ran fine for maybe a mile and then quit. It would fire intermittently but not start. As per standard troubleshooting technique, I slowly replaced each component of the electrical system until i got to the magneto. I pulled the first screw out of the case and water came pouring out. I cleaned out the case and replaced the magneto and it started up on the first crank.

I realize that the wires are coated in epoxy, but the terminals are not. The fabric insulator in the coil holds water and has trouble drying all the way. I'm guessing this was causing a short between the terminals.

-Tyler