Member Contributer RDMcD Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 ok ... 5th gen with 50 000 kms , original electrics. Went out for a ride and noticed my speedo at zero, then bouncing to what seemed to be the correct speed , then back to zero. After some playing around I noticed that it was only correct when accelerating and fell to zero the rest of the time. Before everyone goes all RR on me... while at speed if I pull in the clutch and rev the engine the speedo will stay at zero all day. Again it only works under load when accelerating. Any ideas? I also removed the sensor on the sprocket and the plastic nut seems to be ok. how can I test the sensor itself? Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 ok ... 5th gen with 50 000 kms , original electrics. Went out for a ride and noticed my speedo at zero, then bouncing to what seemed to be the correct speed , then back to zero. After some playing around I noticed that it was only correct when accelerating and fell to zero the rest of the time. Before everyone goes all RR on me... while at speed if I pull in the clutch and rev the engine the speedo will stay at zero all day. Again it only works under load when accelerating. Any ideas? I also removed the sensor on the sprocket and the plastic nut seems to be ok. how can I test the sensor itself? The test procedure is in the service manual. I had the same issue and it turned out to be the sensor and not the plastic nut. The procedure requires a volt meter. If you haven't already done so, down load the manual from the downloads section. Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 30, 2016 Author Member Contributer Share Posted March 30, 2016 thanks Duc.. I guess when all else fails, read the manual! I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral. I'd still like to know why it works under acceleration? Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 thanks Duc.. I guess when all else fails, read the manual! I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral. I'd still like to know why it works under acceleration? The drill trick would work as long as voltage is running through the sensor. If you remove it from the bike, you can still put voltage through it and read the pulses coming from it with a meter. I believe it is a +/- 5 volt. I know I did a post about my venture with this but I'm being a little lazy at the moment to go search for it. Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 30, 2016 Author Member Contributer Share Posted March 30, 2016 thanks again. I'll look into it tonight Link to comment Share on other sites More sharing options...
BrianF Posted March 30, 2016 Share Posted March 30, 2016 My 98 is doing the exact same thing right now. The plastic nut looks good so we're probably stuck with the sensor. I haven't done the test procedure and just continue to ride it because I don't care what the speedo says anyway. Link to comment Share on other sites More sharing options...
Member Contributer MaxSwell Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 When a mechanic (who was new to VFRs) at my Honda dealer was replacing my chain and sprockets it was revealed that the old front sprocket was wider that oem. But no one, including myself, knew the significance of that. On the way to SumSum3 last summer my speedo quit working. Hispanic Slammer correctly diagnosed the problem as the female nut that engages the speedo sensor was not engaging the male part. By sliding the female nut on it's shaft towards the sensor, speed monitoring was restored. Thanks HS. Hopefully your problem is that simple; part numbers 18 and 20, located at the front sprocket, are the culprits: Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 thanks Duc.. I guess when all else fails, read the manual! I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral. I'd still like to know why it works under acceleration? The drill trick would work as long as voltage is running through the sensor. If you remove it from the bike, you can still put voltage through it and read the pulses coming from it with a meter. I believe it is a +/- 5 volt. I know I did a post about my venture with this but I'm being a little lazy at the moment to go search for it. It's 12v. Its power comes trom the tail light circuit. Ciao, Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 30, 2016 Member Contributer Share Posted March 30, 2016 I had a similar problem with the white plastic adaptor for the speedo drive. Someone (not me) had failed to align it with the sprocket nut when tightening the mounting bolts, and the end of the sensor shaft had pushed through the stop on the plastic nut, so the nut was sitting further onto the shaft than it should, and not making good contact with the sprocket nut. Buy yourself a new adaptor, they're only a few dollars. Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 31, 2016 Author Member Contributer Share Posted March 31, 2016 ok somehow the plastic nut has moved on the shaft. Its not engaging with the sprocket nut. Can anyone measure the length of the plastic and the distance between it and the sensor body? Terry .What is the adaptor, the plastic nut ? Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 31, 2016 Member Contributer Share Posted March 31, 2016 The hole through plastic nut should have a solid cap on the end to stop the shaft going right through. Yours has been punched out by mis-assembly at some point, so you can slide the nut along the shaft so that it engages the nut properly, but it is going to slip back along the shaft and disengage the sprocket nut fairly soon. I have been there, and done that. Just buy the new part. US$6.44 from Partzilla, 44808-MR7-013 JOINT, SPEEDOMETER Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 31, 2016 Author Member Contributer Share Posted March 31, 2016 You're right. By me as I just reassembled it a couple weeks ago. Strange that it took several rides to act up ?? Also I think my sunstar sprocket is thinner than stock adding to the problem. Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 31, 2016 Author Member Contributer Share Posted March 31, 2016 just checked... the sunstar sprocket is 9 mm thick and stock is 14mm! Need to add a washer. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted March 31, 2016 Member Contributer Share Posted March 31, 2016 The hole can get punched through the plastic piece if the cover is tightened without the plastic piece seated correctly on the bolt head. Might be able to JB Weld it or something like that? Ciao, Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted March 31, 2016 Author Member Contributer Share Posted March 31, 2016 I've been running this sprocket for 2 years now without a problem. When I measure the nut must have just barely been engaging. Link to comment Share on other sites More sharing options...
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