Using An Ohm Meter

[XJ82YAMAHA]

Can someone please tell me what to set my ohm meter on to test my pick up and coils.. Also tell me what the readings should be on the pick up and coils...

[TopCatGr58]

Well, I don't have an XJ manual, but the XS says for the Pickup coils, you need to be able to measure below 1kohm, should read 720 plus/minus 20% at 68degreesF.

Ignition coils, Primary to primary, set to Ohms, should read 1.5 ohms plus/minus 10%, Secondary set to Kohms, should read 15kohms plus/minus 10%, all at 68 degrees F. HTH.

Diagram shows measuring secondaries thru plug cap, if removed, I believe someone said they are about 3kohm each, but don't quote me!!! Make sure there isn't any rust in the caps, that you have good contact.

[xsivebiker]

TopCat,
Sometime back I purchased a "spare" set of coils with the plug wires and caps off Ebay. My question is: When checking the resistance [ohms] , would there be different values for, say, measuring one set of coils installed on the bike with the battery connected as opposed to measuring a second set of coils with plug wires and caps, NOT installed/connected to anything??
I was just wondering if I purchased a pair of "duds". Adding to my confusion is the fact that my "cheap" meter has only two ohm scales: ohms times 10 and ohms times 1000.
Greg
'80-G
'82 CX500 Custom [Wife's "new" bike]
'79 XL250-S

[TopCatGr58]

Duds or Not

Hey there Xsive,

I'm no electrical guru either, just quoting from the manual. I looked at my spare pair I have , turns out 1 is probably fried, can't get a reading on the Secondary=plug side even after removing the caps. The other has 25Kohms, definitely too much, and one of the caps alone from the Dud was reading 45 kohms, WOW! Yet, both primary were reading 2.5 ohms!!! So, I may have to cut the wires back further and recheck, they might not be total duds, may have to do the replacement wire trick??

With your meter, the Kohm won't be hard to read, the 10 ohms, you just need to move the decimal place I think to the right when measuring the primary. Let's say you get a reading of .25 on the 10 Ohms scale, reducing it to 1 OHMS scale, would give you 2.5 ohms. Are you talking digital or needle, if needle, then just use the scale?? HTH

As far as I can see it, there are only the connectors where the power part plugs into the coils, so if you disconnect them to test them, then you shouldn't get any different readings on or off the bike. But as you can see, some of my caps were fried, so if you're getting funny readings, try taking off the caps and checking them as well as the coils without the caps.

On your bike, you may also have corrosion where the caps attach/screw into the plug wires, so you may want to unscrew them, inspect and cut the wires back a touch if you can't see bright copper wire at the plug wire end where the caps screw in, also take a wire brush to the screw fitting on the cap to remove corrosion before testing or reassembling, not sure if a dab of dielectric grease is recommended when putting the caps back on the wires, perhaps someone more knowledgable can chime in here. Good Luck.