Tach jumping around and bike misfiring *URGENT*
 

I am a new owner of a 2000 HD XL1200 Custom. The bike originally had 13,055 miles on it. After about 800 miles, I started to notice that the tachometer would start jumping around sporadically. The bike did not sound or perform badly, just the RPM needle would jump around. I was watching it so closely that I didn't notice a raised manhole cover and hit a fairly big bump. The tachometer immediately started to work perfectly again. This made me think it was just a loose connection or something. The next day, the tach started to jump around again, except this time, the bike started to spit, sputter and cough. I continued to ride it and when I came to a stop, it cut off. I tried to start it back up but it just backfired and wouldn't catch. I decided to leave it there to "cool off". When I came back to it later that night, it started right up, and ran perfectly for about 15 minutes. The tach began to jump around again, but again the bike did not perform badly. The next morning, I was going to ride it to the dealer to have them check it out. It fired right up and rode fine. After 15-20 minutes, the tach began jumping around violently and at one point I think it spun completely around the dial like a broken wrist watch in a cartoon. At this point the bike is jolting and missing badly. Eventually, it sounded like the engine was running, but there was no response in the throttle. I had to coast it off the highway down an exit ramp and have it towed the rest of the way to the dealer.

This is my first bike, and my first experience with this dealer. I know it's nearly impossible to find out what's wrong with it without looking at it, but I'm wondering if anyone can give me pointers on what I should ask, or make sure the dealer checks. Obviously, I'm sure one of the plugs is completely fouled out by now, but I think there's a bigger problem that's caused it (and possibly related to the tachometer acting up). My dad believes that there could be something wrong with the carb, but wants me to tell the dealer to make sure the head is not warped also. He believes that both of these things could cause the bike to act this way. I just don't want the dealer to replace the spark plug and say, "ALL FIXED!"

Any suggestions?

guess... electronic control module.... be prepared to sell a child or a major body part ..

Had a similar problem with a 99 1200 custom. I was fortunate that I ride with several other folks who have sportsters ranging from the late 80's to 2006. We tried a spare ignition module with no luck, then replaced the coil and the problem went away. Hope this helps. Good luck.

I had a similiar problem with my 2000 883 except it was the speedo droping out and misfiring. It was the battery cable where it terminated at the starter, Take off your seat and you'll see a large harness running down behind the battery cover. Push and pull on it with the bike running and see if it acts up. That's how I tyraced mine. Problem is you have to remove the starter to change the cable, not impossible but it takes some time.

Possibly the crank sensor.The tech will know what to check if he has been around sporties.The head being warped wouldn't affect the tach.The carb wouldn't either.

maybe loose connection/short to battery terminal

Hit that manhole cover one more time and then get back to me.

Check the battery cables first, then maybe the coil. Could just be a loose plug wire too. Check to make sure both ends are pushed on completely.

It's funny you should say that. One time when the bike shut off and wouldn't start back up, I reset the plug wires and it fired right up. I didn't have any tools with me on the side of the highway and resetting the wires was all I could think to even try. It still didn't stay running for long, but it seems crazy that resetting the plug wires made it fire.

I would try the manhole cover thing again if I could get it to run long enough to slam into one. Still waiting to see what the dealer says.