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Buell Motorcycle Forum » Old School Buell » Archives OSB 001 » Archive through July 14, 2007 » Backfires... cuts out... ignition? « Previous Next »

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Jjjoutside
Posted on Friday, July 06, 2007 - 12:21 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Well... I've had the bike about two hours and I already have a problem. Fired it up for a quick ride and about 5 minutes down the road, it started backfiring, popping, etc... barely able to baby it back home... when this happens, the tach dips or drops completely, so I'm assuming ignition issue. I've searched quite a bit and found the sidestand switch issue (this one backfires in neutral though) but not much else. Checked coil connections, etc... any wise thoughts? I'll dig into it a little more in depth tomorrow.

Thanks
JJJ
2000 M2 - stock
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Sparky
Posted on Friday, July 06, 2007 - 03:01 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Probably the wisest thing to do is to get the factory service manual. If you don't have one yet, there is a '96 S1 manual online at Buell.com and somewhere here on the BadWeb that you can use for reference as the ignition circuits are similar.

Until then there are a number of things to check along with the sidestand switch like the master circuit breaker, ignition relay, ignition key switch, RUN/OFF switch, ignition fuse, wire harness chassis grounds, the ignition wires in the harness itself, coil connections and cam position sensor. There's more stuff but these are the main items that need to be verified. Each item as a minimum should be checked for wiring integrity at the terminations. Any loose or corroded connection could be the culprit.

While in gear, the ignition circuit needs a ground for normal operation. This circuit involves all the components mentioned above. But first, temporarily bypass the sidestand switch (short its two wires together) and see if that clears up the problem.
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Jjjoutside
Posted on Friday, July 06, 2007 - 07:34 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Have the manual... been using the diagnostics, but as this is intermittent, it's not much help. That procedure assumes a non-running bike which this is not. Problem occurs in neutral as well, so sidestand switch likely not the culprit... ground straps look fine... loosened and re-tightened them to be safe... no loss of power to any other circuits so not main circuit breaker... Coil connections are clean/solid and it appears to lose primary when this occurs. Just thinking out loud... Going to concentrate on ignition relay, cam sensor, bank angle sensor, and temp sensor next, but I'll have to come up with a way to monitor them in real time so I can see what happens as the ignition cuts out. Could probably bypass the BA sensor and the temp for now...

Thanks
JJJ
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Joesbuell
Posted on Friday, July 06, 2007 - 08:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Side stand switch for sure! this happened to me. I cut and bridged the wires on the side of the road.
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Djkaplan
Posted on Friday, July 06, 2007 - 08:31 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

"But first, temporarily bypass the sidestand switch (short its two wires together) and see if that clears up the problem."

Side stand switch for sure!

You should listen to these guys. It might be doing it in neutral because you might have more than one thing wrong, it could just be intermittent, but at least bypass the switch so you can eliminate it as part of the problem.

Don't complicate things until you have to.
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Jjjoutside
Posted on Friday, July 06, 2007 - 08:41 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Point taken... sounds like the SS switch is something worth defeating anyway. I've never had that on a bike before anyway, so I won't miss it. : )

You may have to slap me every now and then... engineering background makes me want to methodically run through every possibility. Looking at the schematic, it appears that ignition ground comes from three basic points so it shouldn't take long to eliminate that...

JJJ
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Buellfighter
Posted on Friday, July 06, 2007 - 09:43 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Don't forget making sure the battery connections are tight.
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Oldog
Posted on Friday, July 06, 2007 - 09:49 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I had similar problems check the KEY switch, too. nothing on the key except maybe a fob( small )


er and all of the above.
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Jjjoutside
Posted on Friday, July 06, 2007 - 10:50 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Okay... you guys are great. Love the ideas. Bypassed the SS switch, but to no avail (at least I know that won't be a future issue). Same symptom... runs great until it starts to warm up, then cuts out... backfires... tach bounces wildly while happening, so this is mimicked on or back through the coil. Ductaped an LED tester to handlebar... tacked into switch output. LED never flickered and remained on when bike completely died. Plugged another spark plug into each wire and cranked... nice spark. Plugged back into the bike and it fired right up. Rode back to the garage sputtering and backfiring the whole way. Although the plugs look fine, I suppose I should throw a couple new ones in just in case this is a heat-related insulator issue. Starting to lean toward coil since it gets really warm under there... dunno...

Gotta love intermittent problems... Thanks for all the help and keep the thoughts coming. I'm open to anything.

JJJ
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Kmbuell
Posted on Friday, July 06, 2007 - 10:56 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My S-2 did exactly the same thing, it was caused by a broken positive battery cable. It broke right at the connector, under the insulation. And it took several checks to find it. As has been said, gotta love intermittent issues! Might be worth a look if you haven't checked already.
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Cpres
Posted on Friday, July 06, 2007 - 11:36 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

look at the wires on the starter, my m2 had problems like you are describing and I had a broken wire at the starter and in the harness on the shifter side of the bike near the side stand switch at a plug in. I believe the fool at the dealership screwed my stuff up doing warranty work.
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Kyrocket
Posted on Friday, July 06, 2007 - 11:43 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Had the exact same problem about two months ago. The neg. battery terminal had become stripped allowing the bolt to wiggle a little. AND this was not easy to find, but all the expensive stuff runs through your head first. Anyway I retapped the threads and screwed it on tightly and the problem has not showed up again. Good luck, hope that's all it is.


Oh and before you go cutting wires to the sidestand there is a connector there close by (on a '99 X1 anyway) that can be disconnected and I stuck a small piece of metal I found laying in the parking lot to short the two pins and it got me home with no problems, actually I think it's still in there, I better check that!
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Cpres
Posted on Friday, July 06, 2007 - 11:46 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Well I reread your post my Buell is a 2000 M2 Cyclone with the tack kit also the wires on the shifter side are below the battery and near the heim jointed engine mount. Best of luck finding your gremlin and based on the description I had the same issue and that is whet it was broken wires.
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Ryker77
Posted on Friday, July 06, 2007 - 02:56 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

intermittent issues are typically wire realated. Broke wires, corroded wires, loose or dirt ground points..

Use a volt meter and measure the ohms from one end point to another to check each wire.
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Jjjoutside
Posted on Friday, July 06, 2007 - 05:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Coil, gents. Since this was heat related, I pulled out the ole heat gun and started carefully heating up parts (amplifier repair tech in a previous life). Wasn't on the coil for more than 10 sec 'til the bike died. $39 @ HD dealer. Runs like a champ. This is first one I've ever ridden and I think I'm hooked. Thanks to everybody for all the help today. This is a great group.

JJJ
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Kyrocket
Posted on Friday, July 06, 2007 - 09:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

WOW you got out under the Hundred Dollar minimum. That in and of itself requires celebration. Glad you found out what it was and it sounds like it was fairly simple to fix. Sounds like a winner to me, and they are fun to ride aren't they?
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Ryker77
Posted on Saturday, July 07, 2007 - 10:57 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Now that was some McGiever thinking. Heat problem --- heat gun.

Smart!
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