Stumped!

[CD15]

Hi All,
I’m trying to keep my cool, but I’m getting frustrated with my build. I’ve searched the forums and the internet but haven’t had any luck narrowing down my issue.


I have a 1983 XS650 that I bought and turned into a clean chopper (pics below). My dad and I did the work over the winter—wiring, custom front brake system, etc. I rode it this summer—not on long trips, but whenever work and kids gave me the time.


When I first got the bike, it had a failed Pamco ignition. I swapped in a cheap Chinese electronic ignition, but that didn’t last long. I then tried a MikesXS electronic ignition, which we had to modify to get working, but it eventually failed too. For the short time it worked, I didn’t have the problem I’m running into now. Mind you I found it ran hot.


I’m currently running a Boyer Brandsen ignition. I’m not even sure the issue is related to the Boyer, but I’m stumped. I also have a Hugh’s HandBuilt PMA with the correct dual-coil output (within range) for the Boyer setup.


Here’s the problem: I can ride for about half an hour before the bike dies. Usually, I can start it right back up (either push-button or kick), and sometimes it’ll get me home fine, other times it’ll die again. I’ve checked voltage, and it seems to be within spec. While riding, it pulls strong and runs smooth, aside from the occasional backfire. I’ve adjusted the carbs as best as I can, but the right cylinder always seems to run richer than the left.


What could be causing this? I’ve been told to check the diaphragms, but that doesn’t quite make sense to me—there’s no sputter or bogging when riding. It’s smooth and glorious (love this bike), until the issue kicks in halfway through.


Any suggestions would be greatly appreciated!

 

[Max Midnight]

Have you checked that the vent in the fuel cap is clear?

 

[Scottike]

Could be that your ignition coil is going bad. Works fine when it's cold but fails when it gets hot. Once things cool down a bit, it works again. (Edit)-grab a can of air used to blow dust out of computers and use it to quickly cool down your coil and see if it starts working.

 

[Raymond]

For a while, before I learned about this, I was running non-resistor plugs and resistor plug caps, which was fine, until I innocently swapped the plug caps for ones without resistors. The bike would start and run for a little while, a few miles, then shut down. The Boyer ignition was shutting down because it needs 5000 Ω resistance somewhere in the circuit - resistor caps or resistor plugs. Bike would re-start after a little while.

Might not be your problem.

 

[Jan_P]

Please give info on how many fuses there are
And if there is any warnings shutting down backfiring ,Splutter running one cylinder a while

I know Boyer dont like Voltage out of range
And you have fried 2 other ignition systems

Please give more info for now putting it out here .A defect regulator over charging and getting hot shorting out
Just a guess at this point in time

 

[CD15]

Thanks for all the responses. The ignition coil is new but I'll check it again to ensure it's hitting the proper parameters. The plugs I have swapped out and don't see it being the issue however will check to ensure, leave no rock unturned. The vent cap I did check, the cap doesn't have a vent though! Here is a pic, what I did previously wa



The regulator does make me think as I have thought about previously as well because it was one of the things we didn't swap out and was already with the bike. The PMA (Hughs Hand built) was also on the bike when I bought it.



Guys, what about the gas cap? Not sure if it's vented, see pic. I have been reading that this to could be the cause of the issue. Ride for 1/2 hr or so and then bike dies

 

[AUTOMAN]

Like Max said......

If in doubt, run with cap 1/2 off, or, when it starts to die or soon after open the cap and retry.

 

[Jan_P]

This being a later model if stock there can be safety relays I don't know anything about them

 

[CD15]

Yeah I think I'll try that later today, cap half off and see what happens. I'm just curious if that could be the problem, is it possible, does that make sense?

Not stock at all.

 

[Scottike]

Perhaps a clogged fuel filter or fuel line?

 

[AUTOMAN]

Yeah I think I'll try that later today, cap half off and see what happens. I'm just curious if that could be the problem, is it possible, does that make sense?

Not stock at all.

makes sense yes, as long as it vents air when loose

aftermarket cap may seal at 1/2 open

 

[Jim]

I then tried a MikesXS electronic ignition, which we had to modify to get working, but it eventually failed too. For the short time it worked, I didn’t have the problem I’m running into now.

Was that with the same tank and cap you currently have? If the cap was venting fine before all the iggy problems, I suspect it still is.
Now if the tank and cap was changed the same time the problem appeared, that's a whole different kettle of fish... yeah, venting would be suspect.

Here’s the problem: I can ride for about half an hour before the bike dies. Usually, I can start it right back up (either push-button or kick),

A cap with a bad (clogged, missing, whatever) vent, will usually need a bit of time for the low pressure in the tank to equalize and refill the bowls. Normally won't "start right back up."
So again, doesn't really point to tank venting.

 

[Jim]

Is the Boyer iggy box and/or coil located inside your false oil tank? If it is, could be a lack of cooling airflow and overheating box/coil.

 

[Flash1977]

Have you checked all the jets including the round slide, emulsion tube and the needle jet I assumed mine were the same but they were different.

 

[CD15]

Thanks for the help guys, no luck on the gas cap. Went for a ride and had it on half way. Enough for what it seemed it could breath and got down the road and it stalled on me. Fired it back up with no issues and took a 10 or so minute ride with no issues. Not sure what it is, wondering if it is gas related however. Funny thing it does though is sometimes when I engage first gear to go it turns off? This normal?

 

[650Skull]

Raymond made a point earlier on.

Boyer units are very temperamental to small power fluctuations. Boyesr used to post this on their website also stating XS650's could be problematic. Since removed.
Raymond had this cutting out problem for a long time before he found the remedy.

With the 650 having to have a low idle combined with fine tolerances in the clutch, when put in gear it slightly engages, dropping revs for a fraction, this is putting pressure on the charging system causing a slight drop in output maybe causing the boyer to trip.

Q) when it stalls or cuts out on the ride do you turn the ignition key off then on again.

This is how the boyer box is reset if it trips.

If it is the box, you still need to find the cause of a power flutuation

 

[CD15]

I do turn the key off and my kill switch off and on again then fire it up. So maybe it's a battery issue?

 

[Jan_P]

Thermal expansion can close a gap shorting out But so can a Vibration as in taking it down from central stand or Clonk from putting in gear
I think the multiple fried ignition systems is something to investigate / work on

3 before the current Boyer

Experimentally speaking as clear symptom anyone ever gets

When I first got the bike, it had a failed Pamco ignition. I swapped in a cheap Chinese electronic ignition, but that didn’t last long. I then tried a MikesXS electronic ignition, which we had to modify to get working, but it eventually failed too

 

[AUTOMAN]

Jan may have it with relays
Cycle them once or twice, they work for a while.