Custom Build, a year later — I've got problems

poorman9

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It's been three weeks since my bikes ran, and I'm getting sick and tired of it.

Background, here's tons of info about my build. The summery's in the signature - 1981 XS650H, Boyer ignition, Banshee Alternator, kick-only, all custom wiring.

In June I took the bike on a 1000 mile road trip, when I left it was running great. By the last day, sometimes it'd take a few kicks to start, sometimes I'd have to push start it even, but I made it home!

Couple weeks later, after my butt healed. I cleaned the carbs, changed my oil, check my cam chain tension, valve clearance, ect. even after that, it would take maybe 10 kicks to start when it was cold, but only one after that. It was also running rough, plenty of power, just kind of cutting out and choppy at cruising RPMs (I know, carbs, but i swear I cleaned the S#$% out of them).

A the beginning of August, after kicking it for 5 minutes I went out for a ride. Took a break 40 miles from the house and ended up pushing it to the top of a hill so I could drop the clutch and get it started. Maybe a mile away from that, I knew it wouldn't make it home. Even with the choke all the way out, feathering the clutch, revving the throttle I couldn't keep it running. It started surging and finally died.

That was the last time it ran. No matter how much kicking, now it doesn't even try to start. I did find my wiring to my brake switch was intermittently grounding to the frame, so I fixed that last nigh...Still nothing.

  • The petcocks clear
  • There's fuel in the carb bowls
  • Power's making it through my kill switch.
  • I've got spark in both plugs (though it might look a little weak).
  • I thought maybe timing, so I rotated my Boyer plate back and forth a bit, but nothing.
  • Last night I tried spraying starter fluid the carbs, then kicking. I got a fireball at one point...but that's it.

Ideas???:confused::confused::confused:
 
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battery tested good? I know the boyer can be finicky with low voltage, though I'm basing that on my knowledge from the Triumph world rather than for the Boyer for the XS. That's where I'd start.
 
My best guess is low output on the PMA. Have you checked the output voltage at your cap or battery? Most ignitions don't like low voltage or high voltage. A bad reg can give you either.
Leo
 
battery tested good? I know the boyer can be finicky with low voltage, though I'm basing that on my knowledge from the Triumph world rather than for the Boyer for the XS. That's where I'd start.

I was thinking that too, after charging it last night for an hour or so I tested it at 12.8v, threw it in a kicked for a while, still nothing. It at home charging right now though, so we can cross that off for sure tonight.
 
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My best guess is low output on the PMA. Have you checked the output voltage at your cap or battery? Most ignitions don't like low voltage or high voltage. A bad reg can give you either.
Leo

I can't check the output voltage of my PMA unless the bikes running, right?

How's the best place to check the rec/reg if the bike won't start?
 
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hahaha..alright..

Silly but could be true,

Check your ground. Clean it off and reinstall it if you haven't
 
hahaha..alright..

Silly but could be true,

Check your ground. Clean it off and reinstall it if you haven't

Yeah I thought that too, things are getting a little rusty. I heat shrinked a new terminal from the ground to the battery and on the other end, pulled the motor mount and inspected that it was making good contact to clean metal.
 
fuel line filter? if so, is it clean?

is it possible your valvetrain is poopooed? stuck valves? you can do a compression test for this.
 
Yeah, I'm thinking you need to check your compression. You might have burned a valve or something else nasty =(

Check the basics:

compression
fuel
spark

If it's no-go even with starter fluid, then you know it's probably not a fuel issue.

thusly, spark or compression

you've already fiddled with timing. and you can see spark (athough you think it might be weak????)

compression then...
 
With the Boyer you should have a strong spark . Is the Boyer like the Pamco , where , if you disconnect a plug wire to check for spark you can mess up the coil ? Last time I had a motor that did what yours is doing it was a cracked block , so maybe you have air getting in somewhere .
 
fuel line filter? if so, is it clean?

is it possible your valvetrain is poopooed? stuck valves? you can do a compression test for this.

No inline fuel filter...maybe I should have one though hu?


Yeah, I'm thinking you need to check your compression. You might have burned a valve or something else nasty =(

Check the basics:

compression
fuel
spark

If it's no-go even with starter fluid, then you know it's probably not a fuel issue.

thusly, spark or compression

you've already fiddled with timing. and you can see spark (athough you think it might be weak????)

compression then...

Just did a compression test 150psi in both cylinders

With the Boyer you should have a strong spark . Is the Boyer like the Pamco , where , if you disconnect a plug wire to check for spark you can mess up the coil ? Last time I had a motor that did what yours is doing it was a cracked block , so maybe you have air getting in somewhere .

If I fried my coil, wouldn't I not be getting a spark?
 
I just tried spraying starter fluid in the carbs, I got some pops, but nothing resembling an engine that wanted to run.

I've got 12.84v coming out of the battery, and 12.82v coming out of the back side of my kill switch.

hmm.... giving up for the night.
 
compression is good & you have clean carbs.

Is gas getting to the carbs?

If it won't start with starting fluid, then it sounds to me like a spark problem, either timing, or weak/no spark, or other wiring problem keeping the engine from running.

Get some new spark plugs. And then try to figure out which part is giving you the weak spark - coil, points, condenser, electronic ignition, etc...
 
the more I read it, knowing now that you have good compression, the more I feel it's something really simple in your wiring or ignition system. Check your block connectors for loose or burnt wires. See if wiggling the wires creates anything different in the system, like blinking lights(?). Check the connections to each of the ignition components. Maybe you have a bad spark unit(?). I don't know how the boyer system works...

can you swap in stock parts to check?
 
I've got similar things going on just recently, but mine just happens when I ride for an hour or more. I basically let it cool down 5-10 mins and I'm up and running in no time. I think it's my Pamco. I get week or no spark during the cool off time. I'm running a PMA and a capicitor very limited wiring with a toggle. Let me know if you get it up and running. A bunch of us meet on Tuesday nights for moto night. A bunch of old bikes too, few XS's lots of old Honda's and Kawi's.
 
It sure sounds like an ignition problem. Do you have the stock kill switch? They are a known voltage vulture.

Try running a wire directly from the battery to the coils.
 
mattomachu,

When I've had that symptom with the XS it was corrosion in the spark plug leads. Pull the tank, pull the leads off the coils and the plug caps off the end of the leads. Clean the coil and cap terminals, you can use a little twist of sandpaper, a needle file, whatever you can improvise. You can try to clean the copper at the end of the lead or if you have the extra length just snip it back a bit until you get fresh copper. Couldn't hurt to pull apart and clean the connectors on the coil while you're there. If that doesn't fix it the coil itself could be bad. Well they were never great to start with, but in my experience a little water in the end of the spark lead is much more common than a dead coil.
 
Hey GreasyC,
Thanks for the input, what you mentioned is pretty much the only wires that I haven't replaced or messed with at all. I know that the part inside the spark plug boot is corrosion free, but never checked the wires themselves. The wire going to the coil are a little skinny and could probably use some new ones along with new solder. was going to wait til this winter and tear into it again since it runs great until I turn it off from a long trip, We've got a few weekends till the rain starts to drop. Those are quick and easy things that I can tackle one night this week hopefully.
 
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