Rebuilt xs2 with xs650D (77') motor, no spark issue

[Alllooksnnogo]

Hi guys,

First post here. I have been looking around for an answer but unable to find a thread to solve my issue.

I rebuilt my 72' and put a PMA on the bike with a capacitor, kick start only. I set TDC. The electronic ignition was set up previous to the PMA install with the old stator. My issue is spark, or the lack there of. The capacitor is not charged, would this be the issue? I am wondering what feeds the coil initially to power the motor and ignite the process. Do I have to preload the capacitor? I used a battery to mock up the circuit for the lights and the ignition and everything turns on properly. Tomorrow I will check my coil and load at that point but...

Circuit wiring:

PMA to rec/reg
rec/reg (red) to positive on capacitor and to fused circuit positive
rec/reg (green) to negative on capacitor and ground

After the install I had one unused wire (brown, part of neutral circuit) on the old (new style) rec/reg and one (sky blue) wire, part of the old stator circuit.

Any help would be greatly appreciated.

Thanks guys,

Matt

 

[Team Junk]

After the install I had one unused wire (brown, part of neutral circuit) on the old (new style) rec/reg and one (sky blue) wire, part of the old stator circuit.

I think you have things turned about a little. The sky blue is your wire to the neutral switch and the brown went to your regulator.

Try temporarily replacing the cap with a battery and see if it sparks.

 

[Alllooksnnogo]

Thinking the same man, I will try this morning and see what happens.

 

[Alllooksnnogo]

Ok so I have no idea now lol.....I just mocked up the circuit with a battery and checked for spark and I have it!? Then I put the plugs back in and ran it, shut it off and reinstalled the capacitor and nothing!? This is confusing because I am generating the power from the stator through the rectifier and to the coil. The battery or capacitor is only there to store electricity for my lights! Am I missing something?

 

[Jim]

The battery or capacitor is only there to store electricity for my lights! Am I missing something?

Yup.
The battery or cap isn't just for the lights, it's also what powers the ignition sys.
You say it runs with a battery in the system but not with the cap. Means either the cap is faulty or (more likely) you're not charging.
Try putting the batt back in and see if voltage at the batt climbs as you rev the motor. About 3k revs should show a climb to about 14v.

 

[GLJ]

Dumb question. Are you trying to start it with the lights turned on?

 

[Alllooksnnogo]

Gentleman thank you for the advice.

GLJ, the lights come on in the battery mockup when the ignition is keyed on allowing power to coil.

Jim thank you ok so this is where I was confused. I just tried it without either cap or battery just to prove that before I saw your post. Ok this makes sense to me. The cap is not preloaded or charged and the lights do not come on when ignition on, but of course in the battery circuit they do. Should the stator automatically start charging the capacitor as I turn the motor over with the kick? Potential bad capacitor? I'll advance on your advice next with the charging of the battery. I'll do this now

 

[Jim]

Should the stator automatically start charging the capacitor as I turn the motor over with the kick?

Yes. That's how a cap system works. Soon as the motor spins, the PMA sends out power.... volts, watts.... whatever helps your understanding. That charges the cap. The stored energy in the cap along with whatever the PMA puts out is used to charge the coil and iggy system.
If the PMA's not working, the whole works is dead in the water. Best test is like I said before, get it running on the battery and put a meter on it to see if the PMA is working.

 

[Alllooksnnogo]

Ok Jim, well it appears that the battery did charge. (Origional reading was 9.6 and now 11.5) I kicked the motor orver and it started but revved high like the carb was stick open (running makuni) I hit the kill switch now I cant get the blaated thing started again....perhaps I flooded it?

 

[Alllooksnnogo]

I do have another cap I will try next if I can get it started again. I'll give it a few minutes.

 

[arcticXS]

Using a capacitor was the only alternative to the heavy and bulky lead acid batteries in the 70s/80s/90s. With the caveat that the generator/ alternator was PMA. Which ruled out Yamaha RD/ XS/TX models of the day.
Today, there are two much better alternatives. A CDI/ PMA system like VAPE/ Powerdynamo/ MZb, which is a very good system. Or use whatever PMA with a small and lightweight LiPoFe battery. I really like "Super B" brand.
Using a capacitor is just about as backwards as installing an 8- track tape deck in a Prius or Tesla......

 

[GLJ]

GLJ, the lights come on in the battery mockup when the ignition is keyed on allowing power to coil.

I do not think at kicking speed the PMA will create enough power to run the lights and ignition.

 

[Alllooksnnogo]

Boys now I cant even get the thing started again even with the battery set up. Charging system pma looked to be charging the battery but yes I'm not sure on the capacitor. I'll do some more testing if I figure out why it won't start now and if I get fed up I'll go with a lithium in the box

 

[Alllooksnnogo]

My mock set up right now with rec/reg positive to ignition and battery and other side grounded