| Author | Message | ||
     Gnutlethal |
Hi folks, last week the seal in one of my fork legs suddenly and quite violently blew, so that fork oil sprayed over the whole right side of the bike almost to the rear tire while driving. Have to say that I really hate this messy job, but it was easy to do fortunately. The only other casualty was the locking mechanism of the seat, that had to be replaced by a long regular bolt. It isn't funny when you have to clench your ass to not risk loosing your seat. And after wrenching around for a few hours, I decided I could re-attach the chin fairing again. A little tinkering that is no repair is fun, too. Anyways, I still got a problem with my tachometer. The needle is all jerky and shaking around. As long as I travel at constant speeds, there's no problem. As soon as I open the throttle, the needle bounces upwards, returns to where it belongs, bounces and shakes again. And so on, rinse repeat. It always jerks upwards, never below the real revs. And the movement is very sharp and shaking. If I close the throttle, the needle gracefully sweeps down like the revs do, without any error. I checked the wires for chafing and cleaned the screws that attach the wires to the back of the tachometer. No luck. Do I have a defective tachometer unit or is there anywhere else I could look for the problem? Thank you very much! (EDIT: I mixed up tachometer and speedometer... Sadly cannot change the topic of the thread)           (Message edited by gnutlethal on July 16, 2013) | ||
| Gnutlethal |
Forgot the video showing the jerky needle. Please take a look and gimme a hint where to look for the cause of this problem. Thanks | ||
| Reepicheep |
Speedo sensor failures are very common on the tubers. If you replace it, change the V+ feed from the general +12V bike power bus to the 5V feed from the ECM. The sensor is magnetic, so you can pull it and clean off any metal. That might help. Then wait and see if it gets better or worse... usually they get intermittent for a short time and then fail completely. | ||
| Gnutlethal |
Thanks for your reply, Reepicheep. Sorry, I guess my English skills are truly lacking. Just remembered that it's the "tachometer" that is not working right. Perhaps I should say "RPM counter".  In my native language the "tachometer" is the one showing the speed that you are going. My bike has had this problem for the last four years. (Message edited by gnutlethal on July 16, 2013) | ||
| Reepicheep |
Ah! Well, it would have helped if I had watched the video. That could be the crank position sensor (or associated wiring). Careful, when it dies completely the bike will die and it could leave you stranded. Do you have access to an oscilloscope? | ||
| Gnutlethal |
Sadly no advanced electronic equipment here, just a simple multimeter. I just can't think of the crank position sensor being shot, since I've never had any ignition problems whatsoever. No popping, no misfire, no malfunctions. Except once, when the damn sidestand switch failed... The wiring is absolutely pristine in condition. I guess you'd want me to build the "test wiring harness" that the factory service manual is talking about? Good idea. I'll have to find out if I can borrow an oscilloscope anywhere. | ||
| Reepicheep |
Not sure about the tubers, but on the XB's the CPS signal line goes straight to the ECM, so the only "test harness" you need is a bent paper clip to go into the connector from the back while it is still connected. It's obvious if your CPS is dropping pulses. I have a thread here showing scope traces. You can get a DSO Nano scope for $75 or so on ebay. |
