bortustortus

XS650 New Member
Messages
1
Reaction score
3
Points
3
Location
midwest
Hello, I recently aquired a 1979 XS650 SF with a points ignition system. The bike has no spark and while trying to diagnose it I decided to set the points. I watched a video on youtube (
) that shows how to set the points. Included in that link is a timestamp to where he uses a 12v test light to set the points. When the points are opened the light lights up, when closed, the light shuts off. My light does not turn off, instead it stays on the entire time. Not much of an electrician and have even less knowledge on points ignition systems. My wire running the main fuse also gets extremely hot after the ignition is left on for more than a minute, not sure if it's factory wiring, or if these problems are related. One other quick question, when testing your ignition coil, do you remove the spark plug wire? Testing the coils, the primary is slightly out of spec, although something tells me there are other ignition issues at hand. Thank you all.
 
My light does not turn off, instead it stays on the entire time.
When the points are closed, all power goes to ground, so the light's out... ground is the path of least resistance. When the points are open, through the bulb is the least resistance... it's the only path actually.

So, if the light stays on, it means the points are never closing and dumping the power to ground.
My wire running the main fuse also gets extremely hot after the ignition is left on for more than a minute
Check the primary resistance of each coil. If one is low, it'll draw more current than it should. A hot (temp) wire indicates too much current flow. The primary should read about 3-4Ω iirc


EDIT: more thinkin'.... if the light's on, means the points are open..... means the coil isn't being charged... means there shouldn't be any current flow (other than what the test light draws. Doesn't make sense... :umm:
Try putting the kill switch in "kill" and see if that wire still gets hot.
 
Well, one set of points is remaining open, but that doesn't mean the other set is. If it's setting is way off, it may be remaining closed all the time, and that would constantly be charging up it's coil.
 
Well, one set of points is remaining open, but that doesn't mean the other set is. If it's setting is way off, it may be remaining closed all the time, and that would constantly be charging up it's coil.

A coil has about 4Ω resistance. That works out to about 3amps current draw. A 16-18awg wire won't get hot pulling that much power... even for extended periods.
 
Left of field here, but when the cam chain is past it's use by date, some lazy bastards, rather than replace it, file the points backing plate so they can rotate the plate around further, so, if the points plate is turned around far enough the points spring will ground on the bucket. You can also check to make sure some clutz hasn't forgot to replace the insulators between the points spring and the base, it was missing on one of my points.
Not likely, but my bike came with both issues.
 
Back
Top