Way off topic for Yamaha XS650 List, but it is a Motorcycle!

kshansen

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Wish there was the old Sportster.org list still around but as of now you people are the best source of ideas I know of. Don't expect a specific answer but just fishing for ideas.

Today decided to go for wife to a nearby Drive-in-Hamburger stand for lunch. Her on her Vespa and me on the 1992 Sportster/Sidecar outfit.

About two miles from home the Sportster bucked a couple times, at first thought was maybe low on fuel but then noticed the second it bucked the tach dropped to zero and just as fast it picked up running great. Turned around to go home and it did it a couple more times. One time while at a traffic light it just quit but a quick touch of the start button and it fired right up.

Other than the cutting out for a second it runs good and as smooth as any Sportster(1992) does. Kind of wish it would cut out and stay dead for enough time to do some basic checks. Right now about the only thing I can think of is to start it and just let it idle to see if I can have it happen while not riding. At least that way I might stand a chance of being able to see if say lights go out indicating a bad circuit breaker or key switch.

It is full electronic ignition so could be a bad pick-up or ignition module. But seem like they would be more likely to fail when hot and then take cooling down to start working again.

Anyone who may have ideas on how to check for a very intermittent and brief failure I would love to hear some ideas. If I could just get it to happen at a regular rate so I could know if I found the problem it would be great.
 
Anyone who may have ideas on how to check for a very intermittent and brief failure I would love to hear some ideas.
About all you can do for that quick of a fault is just start checking and cleaning connectors. Sounds like a connection intermittently opening up.... I'd start with iggy connectors and broaden out from there.
 
The sportster engined Buells are famous for a ground connector failing. Actually that's popular with many bikes.The 14 concours has a connection block called the spider. known failure point.
Replace all the fuses cuz they can LOOK good...
Don't rule out water in the gas.
 
Don't rule out water in the gas.
I'm assuming the tach is electronic and fed from the iggy brain box. It dropping to 0 when motor bucks kinda points to either iggy or main power... yeah, and associated grounds. Would be useful to know if lights dropped out too. Good call on replacing the fuses. Extremely rare... but I've seen an intermittent fuse connection.
 
Only time I was bucking, one of the ignition wires had pulled out of the coil to the point it was sitting right at the hairy edge. Now I wrap electrical tape around the wire, up around the terminal, and back down around the wire again.
 
I'm assuming the tach is electronic and fed from the iggy brain box. It dropping to 0 when motor bucks kinda points to either iggy or main power... yeah, and associated grounds. Would be useful to know if lights dropped out too. Good call on replacing the fuses. Extremely rare... but I've seen an intermittent fuse connection.
Yes tach is electronic.
Yes would be nice but it was a sunny day and not easy to see lights while riding! Was hoping for it to die at home in garage tonight but ran it for several minutes with not so much as a hick-up. I even used plastic rod to tap on things with it running hoping for a loose connection.

Can't replace fuses as it has circuit breakers! Did note one of the breakers had a terminal that was getting very warm, it was the breaker for the lights. As far as I can recall they have not been replaced or I just forgot to note it in my service records. Being a 1992 bike I think now would be a good time to replace all four breakers.

Also all the wires from the breakers go through a quick connect which also was warm, could be from the wire to the light system breaker. I did pop all the male terminals out of the connector half and no sign of corrosion and they fit snug in the female half. Any how I have a new Sure-Seal connector set and terminals so think I will use that. The factory Harley connector has no sealing of any kind.
 
Can't replace fuses as it has circuit breakers! Did note one of the breakers had a terminal that was getting very warm, it was the breaker for the lights. As far as I can recall they have not been replaced or I just forgot to note it in my service records. Being a 1992 bike I think now would be a good time to replace all four breakers.
One of the hardest problems to figure out that I ever experienced was an intermittent circuit breaker on a Sportster. So you're right, I would start there. An equally vexing intermittent problem turned out to be a bad connection on a hidden kill switch that I had added -- also on a Sportster. They do vibrate. So, next, I would check all connections, not just visually, but by pulling on them.

Wish there was the old Sportster.org list still around
Have you tried www.xlforum.net ?
 
Also, standard troubleshooting for an intermittent ignition problem is to run a wire directly from the battery to the coil -- fuse it for safety if you want to, and put a an on/off switch in it for convienence if you want to. This will eliminate a lot of wires and devices. Ride around, and if the direct wire solves the problem, you just have to troubleshoot the stuff you just bypassed.
 
I second xlforum.net best sportster forum out there. I am hoping one day I can get another sportster going. Love those little things. Last one I had was an 04 883. Wanted to build a 1250cc monster out of it, but life happened and all my motorcycle dreams are a pile of xs650 parts in the garage for now.
 
How's the ignition switch? My SG switch was about to lose it's assembly screws when It was hiccupping.
 
Well I'll have to check out the xlforum.net. I tried a couple Facebook groups and they seemed to be more about "Does this farkle make my bike look better parked at the doughnut shop?"

Yes electronic tach, so obvious some kind of electrical fault.

The problem did start not long after a right hand turn so guess there is a chance I had bumped the kill switch while turning on the signal and as I do not use it very often the contacts inside could be a bit dirty and were making intermittent contact.

Right now I'm thinking that if the problem was in either the pick-up or the ignition module they would be more of a heat related problem and need a cool down time to start working again.

Like I said this one is a full off to running great in less that blink of the eye. Even when it died at the stop light it just took a tap of the start button to fire back up and after that it ran good the three miles back home without a miss.

I did check the plug wires and they seem nice and tight in the coil and at the plugs, but even if they were loose causing a miss I would not expect that to effect the tach reading.

The worst part is the random and short lived failure mode. If it would stay dead for long enough to check something it would not be as much a guessing game. Or if it would do it after a set period of time again you could have some confidence you found the problem.
 
Also from the buell forums, circuit breakers AND relays as issues, intermittent sidestand switch popular too.
 
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