Bike won’t stay running after HHB PMA/Ignition swap


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Minneapolis Minnesota
Before I contact Hugh’s hand built again, I figured I’d ask you guys and Facebook first. I am at my wits end though, spending days and days trying figure this out so I truly need some help.

1980 xs650 special bs34’s

Prior to swap:
Everything bone stock. Fired up and idled alright, but boggy and stuttering 0-40 mph 1st-3rd gear. Left plug fouled, either carbon or most likely gas. Right plug looked good. Cleaned carbs and they were dirty but nothing was clogged. The left carb has original brass float that looks pretty ancient and the right has after market brass float that looks new. The right slide diaphragm had about 1/2 inch of delamination on the rim, but no holes through so I carefully patched it with E6000 adhesive. The left diaphragm was good (side with fouled plug).

Put carb back on same exact issue. Ended up swapping to uni foam pods at his point because the oem air filters were hard to find. No change after pods.

Swapped to Hugh’s Hand Built PMA and CDI ignition kit.

Pulled entire wire harness, installed PMA and timing tab, marked tdc on case cover, temporarily wired PMA, pick up coil, CDI, reg/rec, ignition coil and capacitor triple checking my connections and had good frame grounds. Made sure to ground body of reg/rec. Wired 20 amp fuse from + spade of capacitor. Grounded other spade of capacitor. Didn’t wire any lights, switches or anything but what is mentioned above.

Kick, kick, kick and the most I’d get was a sputter of a start. Took off capacitor and wired up everything the same but with a battery. Didn’t use the relay that was included in the kit though, which in my understanding is only necessary if you’re using a key or starter button. Battery grounded to frame, all other grounds straight to negative post on battery. Hot wired the starter to battery and bike starts, but starts to miss and stumble then kills. Got a 14.8 volt charge spec on battery though. Tried all adjustments on timing tab and no real change. Pulled plugs which are gapped properly per Hugh’s instructions, and problematic left plug was wet with gas and didn’t seem to have fired much if at all. Right plug looks alright, from what I can gather with brand new plugs and not ever getting motor up to heat.

Lowered left float bowl float, no change. Did ohms test on all new components per Hugh’s instructions and all seemed to be close to spec although my numbers were a bit off and I’m using the cheapest multimeter you can buy at Walmart. Most importantly the ignition coil resistance from spade to plug wire was nothing/open circuit so I believe the coil isn’t shorted internally.

Last thing I tried was reversing the spade leads on coil, wiring them opposite to what Hugh’s instructions said. Initially it fired and ran better and longer then it ever has since swap. But killed abruptly and difficult to get started again. Whenever the bike kills throughout all these changes, I have to wait a a good 5-10 minutes to get it started again, which leads me to believe at least that left cylinder is getting flooded.

I’m at my wits end, spending every waking moment trying to figure this out. At this point I need some help.

Thank you for reading this long story.



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Are both sides firing on the timing light ?
No Relay ? Do you have a kill switch ?

I'm think problems in the carb on the side that's not firing.
Sage advice .

Battery-less - PMA Capacitor - E-Advancer

Standard Recommendation
...........My standard recommendation is to wire the PAMCO temporarily to a separate battery to get the engine running so you can trouble shoot the PMA.........One of four things will happen when you first fire up a PMA conversion:
1, ........The engine will start immediately, you will get 14.5 Volts on the cap and life will be beautiful! (Yeah, right...)
2,......... The engine will not start because you are getting zero output from the PMA and you will break your leg kicking it with no joy....
3, .........The engine will start immediately but the PMA will produce a destructive 20+ Volts and fry the entire electrical system, including the PAMCO...
4,...... ..The engine will start immediately but because you wired the capacitor in backwards the cap will explode and spray shrapnel all over the garage, killing the cat........Be careful and use a Voltmeter.......
Caution,...........If you have the capacitor wired in with reverse polarity, it will blow up as soon as the engine starts, so wear safety glasses (this is no joke).

It is becoming increasingly apparent that the majority of posts requesting help with a PAMCO installation involve a PMA. There are now more than a few PMA setups available including a bunch of home made setups that do not always match the regulator with the PMA. Other PMA issues can involve the use of a PMA with more power than is necessary to power up the XS650 resulting in an excess of current and / or Voltage which is dissipated in the form of heat by the shunt type regulator. To add to the complications of a PMA setup, it is now very popular to substitute a capacitor for the battery which then introduces even more potential complications. Many of these PMA setups, especially the capacitor variety, are done without any careful thought given to the dynamics of the setup requiring a degree of balance among all of the parts. PMA's with a high output. Poor quality capacitors chosen randomly based on cost and physical size rather than suitability for the intended purpose. Haphazard wiring and installation to get on the road quickly without benefit of any electrical testing. The use of tiny batteries that work for a few miles before succumbing to the heat from an excessive amount of charging current. Somehow, the PAMO and other electrical equipment is supposed to survive this abuse. The typical failure is often after the bike has somehow survived the poor PMA setup for a few miles or even a few months of abuse before it finally succumbs, leaving no way to test the PMA because the engine will no longer start. A replacement PAMCO may be installed and the cycle then continues because the root cause was not discovered due to the urge to get back on the road while there is still some of the season remaining. I am quite often asked to provide installation guidance for a PMA setup even though there are dozens of possible setups and I do not manufacture, sell or service a PMA. Some thought has to be focused on reducing or eliminating the impact of PMA's on the functionality of the PAMCO and its warranty.
Cruzin Image has replacement slides with diaphragms attached for reasonable.
I’d put in a matching floats, too. may have the genuine articles for reasonable.
I have no comment on the PMA.
I agree . The problem existed before the PMA/CDI swap. The slides and float are both suspect. Somebody has been in at least one of the carbs.

I posted about the PMA because of concerns about not using the kill relay among other things.
I would suggest a handlebar kill switch , stuff happens. But first have a look at this.
Yeah I’m definitely going to put in a kill switch. I’m just mocking it up until it runs right. And boy am I glad that I went that route. I’m about to buy these used VM34’s and go on a scavenger hunt for the right jets/slides etc. the several jets dude has with the carbs might be right though