1976 XS650 Starving for Fuel?

Wilsonsk

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Yes if you have them in house Coils
As i read it solid 12.7 V disconnected but still stumbling and losing power.

I would have a quick check inside the kill switch
I have both of my old ones, I believe they worked, I honestly can't remember if I fired it before I put the new coils on or not.

If I find out it's coils, is there a best choice for new ones? Should I switch to TCI? The coils Dennis Kirk carries are Emgo.
Screenshot 2023-08-24 143018.jpg


I'll try coil swapping first, depending on what I find there I'll move to the kill switch. I did wiggle the kill switch a little both directions to see if it had a poor contact or something, I have to move it quite a ways either direction and it shuts off decisively, it's new, aftermarket, but new.
 

Bruno_c

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I suggest you should first determine if the malfunction affects one cylinder or both.
Pull one plug cap then the other and see how it works.
 

gggGary

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An inline spark tester will quickly show misfiring. Have you set the the valves cam chain yet.
 

Grimly

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A coil might draw 4 Amps at idle but will rapidly decrease its current demand as the revs go up, dropping to 2 Amps or so. This is caused by the reduced charging time the points give it as the revs rise.
 

Wilsonsk

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I pulled the plugs, which were new Monday, I started fresh since I was jetting. Thr right was a little darker than the left so I swapped that new coil for an old one. Got 18 miles (most of which at 70 mph, no stop signs, one u turn half way) in without incident, AND the bottom end seems fine, I’ve been through 4 or 5 pilot jet changes trying to fix the idle/ off idle. My charging is still wacky, may not be related, I’ll clean up connectors later. Fingers crossed, even seem to have my jetting pretty close, left plug looked just a tad dark, right darker.
IMG_4849.jpeg
 

Wilsonsk

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Since we’re on the topic,
Are there good new coils out there?
Are the Emgo coils I bought junk or did I just get a bad one?
Are the components for TCI any better? More reliable?
 

Wilsonsk

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Got another 20 miles on, 40-60 mph. No issues other than my charging. I unplugged the voltage regulator and rectifier, terminals look pretty good. Idling @ 1200 I get 14.2, at 60 mph I have 13, if I pull in the clutch and let the engine slow down, the volts climb to 14.2 as the engine slows to idle. It’s not jumping around anymore, just goes down as rpms go up.
 

Jan_P

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Got another 20 miles on, 40-60 mph. No issues other than my charging. I unplugged the voltage regulator and rectifier, terminals look pretty good. Idling @ 1200 I get 14.2, at 60 mph I have 13, if I pull in the clutch and let the engine slow down, the volts climb to 14.2 as the engine slows to idle. It’s not jumping around anymore, just goes down as rpms go up.

Please describe the charging problem
Not charging at idle is normal the 13 V looks right ..as long as it is 14 .2 ish at normal rev

How is it at 70 mph longer runs getting the heat up with the current setup
 

Wilsonsk

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Please describe the charging problem
Not charging at idle is normal the 13 V looks right ..as long as it is 14 .2 ish at normal rev

How is it at 70 mph longer runs getting the heat up with the current setup
Current Charging situation:
Idle 1200 rpms - 14.2 volts
70 mph/~4,000 rpms - 13.0 volts
Volts go down as rpms go up, very stable now, not jumping around, very consistent.
I have LED headlight and tail light

I got ~40 miles in last night @ 60-70mph, no issues.

Is it possible the remaining Emgo coil is causing a problem? Again, the voltage dropping was there before I swapped out the left Emgo coil with the old OEM coil, but intermediate and possible tied to my coil cutting in and out, now I seem to have normal operation, and steady but low voltage at cruising RPMs, good voltage at 1200 RPM idle.
 
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Jan_P

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13 V is still battery
70 mph/~4,000 rpms - 13.0 volts
And no Charging ( or excessvie consumption )
I would replace the other coil as well If in House and OK
 

Wilsonsk

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13 V is still battery
70 mph/~4,000 rpms - 13.0 volts
And no Charging ( or excessvie consumption )
I would replace the other coil as well If in House and OK
Will do, I'll try to get it in at lunch time. I may even stand a chance of being able to return the Emgos, Dennis Kirk is just down the road and they are pretty accommodating in person.
 

Wilsonsk

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Will do, I'll try to get it in at lunch time. I may even stand a chance of being able to return the Emgos, Dennis Kirk is just down the road and they are pretty accommodating in person.
I put in the other original coil, charging situation seems better but not completely gone. Driveability situation is still good! !0 miles or so at 60-70 mph sustained.

Idle at 1,200 rpm - 14.4 volts
60 mph/~3,500 rpm - 14.0-14.1
70 mph/~4,000 rpm - 13.1-13.3 intially, seemed to recover once at speed to 14.0-14.1, but adding throttle pulled it back down in the 13s
Still pulls down to 13.0-13.1 on acceleration

Doesn't really make sense that electrical load should increase with rpms/acceleration. Dirty slip rings maybe? I did check the brushes, there is plenty there.

I have a 1981 donor motor with the A type rotor/stator and pickup for TCI. I purchased the GN250 module and the Honda coil to convert (at some point) to TCI. It seems like ignition parts are more readily available for TCI, should I be swapping everything over?
 

Jan_P

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Difficult to know

70 mph/~4,000 rpm - 13.1-13.3 intially, seemed to recover once at speed to 14.0-14.1, but adding throttle pulled it back down in the 13s
Still pulls down to 13.0-13.1 on acceleration


I read it as a wire or something moving position via inertia shorting out and then at steady state works as it should.
Can be anywhere on the machine and not specifically to the Ignition.

I would wait replacing alternator provided slip ring resistance is OK .
And inspect wiring at known problem places Headlamp rubber grommet and so on.

But At times replacing parts is one way forward.

Maybe a second run with the alternator disconnected se if fluctuates
If not the Alternator shift makes more sense
 

gggGary

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You still running the mechanical voltage regulator?
:twocents: I wouldn't change out a working points system "just because"
They are not quite as accurate as a crank drive electronic system but it's redundant (two completely separate ignition systems) and is stone reliable if the easy regular maintenance is done on schedule. The accuracy is plenty good enough for a street ridden XS650 motor.
 
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Wilsonsk

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Difficult to know

70 mph/~4,000 rpm - 13.1-13.3 intially, seemed to recover once at speed to 14.0-14.1, but adding throttle pulled it back down in the 13s
Still pulls down to 13.0-13.1 on acceleration


I read it as a wire or something moving position via inertia shorting out and then at steady state works as it should.
Can be anywhere on the machine and not specifically to the Ignition.

I would wait replacing alternator provided slip ring resistance is OK .
And inspect wiring at known problem places Headlamp rubber grommet and so on.

But At times replacing parts is one way forward.

Maybe a second run with the alternator disconnected se if fluctuates
If not the Alternator shift makes more sense
Maybe a second run with the alternator disconnected se if fluctuates
If not the Alternator shift makes more sense

I can do this again, I watched it VERY closely yesterday and it never wavered

I read it as a wire or something moving position via inertia shorting out and then at steady state works as it should.
Can be anywhere on the machine and not specifically to the Ignition.

I'll trace some wires, could be motor vibration frequency related, it will do it revving it sitting still as well.

But At times replacing parts is one way forward.
I'm saving this for a last ditch effort. I'll pull the cover off and clean the slip rings and ohm rotor. I'm going to pull the stator and rotor from my parts motor as well, check that one too, I could swap rotors if they both test good, then I have the magnet for the TCI pickup done when I do eventually go that way.
 

gggGary

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Some aftermarket rotors had a wobble that could make the brushes skip.
Easy enough to do a visual check. of rotor runout.
Sometimes it was just varnish that got slopped in the taper, easy to remove.
 

Wilsonsk

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You still running the mechanical voltage regulator?
:twocents: I wouldn't change out a working points system "just because"
They are not quite as accurate as a crank drive electronic system but it's redundant (two completley separate igniton systems) and is stone reliable if the easy regular maintenance is done on schedule. The accuracy is plenty good enough for a street ridden XS650 motor.
You still running the mechanical voltage regulator?
I changed to a VR115 and a new 3 phase rectifier, 50A, about a week ago. I watched teh voltage after I put that in, every time I looked down it was 14.2-14.4, but I wasn't watching it while accelerating or at high speed. I replaced the mechanical VR and rectifier because it was running low, I adjusted it and then it went high, I adjusted it again and it was pretty good, but it roamed around between 12.9 and 15.5. In hindsight it may have been the same issue.

I wouldn't change out a working points system "just because"
They are not quite as accurate as a crank drive electronic system but it's redundant (two completley separate igniton systems) and is stone reliable if the easy regular maintenance is done on schedule. The accuracy is plenty good enough for a street ridden XS650 motor.
I agree, I have a 41 Ford Tudor, 49 Ford 8N, 50 Farmall H, all with points. I had an issue that went on for a year or so with the Farmall running bad, turns out I needed to put in a third new condenser to get it to run smooth. That was after fitting and reaming the distributor shaft bushing, compression checks and lots of head scratching. I have a LOT of faith fundamentally in points ignition, you almost always can make them at least run without a trip to the parts store. The problem I keep seeing is that no one makes points parts in volume anymore and the quality is horrible. I'm pretty sure my 41 Ford (49 8BA Flathead in it) is still running 50s vintage points (maybe original), they look ancient, but clean up well and run well. The coil on that failed recently (looked like that was original), went through 2 new ones to replace it, first was DOA. All of that to say, I will change to TCI at some point, but I want to determine what is going on here, lots of potential suspects, most of which wont change with a change to TCI.
 

Wilsonsk

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Some aftermarket rotors had a wobble that could make the brushes skip.
Easy enough to do a visual check. of rotor runout.
Sometimes it was just varnish that got slopped in the taper, easy to remove.
I'll check my rotors (1981 and 1976) and report back for runout, ohms and cleanliness/smoothliness.
 
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