First Failure for 26 Year Old Bike - A Tach?
#1
First Failure for 26 Year Old Bike - A Tach?
Eh...other than dirty and neglected carbs, my trusty '91 has been bombproof. Until two days ago, that is.
Headed home from a short ride, I looked down and the tach was sitting at 7K whilst at a stoplight. Say wha? Revved the engine and it went to 10K and fell back to 4K, with a few hesitations inbetween.
Bike is in the garage now, with the tach sitting at 4K. While the bike has been kept immaculately clean through the years, obviously some bit of crud has managed to work its way into the gap between the magnets & coil on the tach. Now, I know of several companies that specialize in the repair of such meters, but the low end cost is probably around $100 or so.
I'm sure a lot of guys would use this as an excuse to swap in a new digital cluster, but I happen to really like the look of the stock setup. So...anyone tackle such a repair (cleaning the magnet gap)?
There's also a lot of guys who have swapped out the stock cluster for digital ones. If ya happen to read this and still have your old gauges, man, I'd love to hear from ya.
Headed home from a short ride, I looked down and the tach was sitting at 7K whilst at a stoplight. Say wha? Revved the engine and it went to 10K and fell back to 4K, with a few hesitations inbetween.
Bike is in the garage now, with the tach sitting at 4K. While the bike has been kept immaculately clean through the years, obviously some bit of crud has managed to work its way into the gap between the magnets & coil on the tach. Now, I know of several companies that specialize in the repair of such meters, but the low end cost is probably around $100 or so.
I'm sure a lot of guys would use this as an excuse to swap in a new digital cluster, but I happen to really like the look of the stock setup. So...anyone tackle such a repair (cleaning the magnet gap)?
There's also a lot of guys who have swapped out the stock cluster for digital ones. If ya happen to read this and still have your old gauges, man, I'd love to hear from ya.
#3
Yeah, that's the plan. But my day job is restoring vintage audio gear, and I'm well familiar with flaky analog gauges, and debris in the magnet gap is the most common issue, and I'm all but certain that that is the issue here. The gap is narrow (<0.010") and it seems that nearly always whatever gets stuck in there is magnetic, which means finding and removing it is a real exercise in micro-surgery.
#4
#5
#6
The tach can be removed on its own...I've seen them selling from time to time. Moving the needle won't accomplish much except making the situation worse by having a sticky needle AND an inaccurate one.
The analog tach on these bikes is nothing more than a leaky voltmeter. The input from the ignition module is rectified and filtered and presented to the analog gauge, which shows a voltage. More revs = higher voltage. I believe there's an adjustment for rise and fall time on these tachs, but I'll have to wait till I pull this one apart to see. I'll try to reverse engineer the electronics when I have it apart, just 'cause I like to do that stuff.
Anyway, 99% certain that crud in the magnet gap is the root issue, and clever though I may be with this stuff, it's still probably the kind of thing that a professional who does this type of thing daily will have to tackle. Cheapest fix is replacement, if a working one can be found.
The analog tach on these bikes is nothing more than a leaky voltmeter. The input from the ignition module is rectified and filtered and presented to the analog gauge, which shows a voltage. More revs = higher voltage. I believe there's an adjustment for rise and fall time on these tachs, but I'll have to wait till I pull this one apart to see. I'll try to reverse engineer the electronics when I have it apart, just 'cause I like to do that stuff.
Anyway, 99% certain that crud in the magnet gap is the root issue, and clever though I may be with this stuff, it's still probably the kind of thing that a professional who does this type of thing daily will have to tackle. Cheapest fix is replacement, if a working one can be found.
#7
#8
#9
Got a replacement tach from eBay for a really cheap price, but I wanted to see if the old gauge could be fixed. Pulled it apart since I had to fool with the lamps for the nth time anyway, and carefully blasted the gauge innards with compressed air. Amazingly enough, that seemed to take care of it!
Sometimes, chit just works out. For me, not that often, but even a busted clock is right twice a day.
Sometimes, chit just works out. For me, not that often, but even a busted clock is right twice a day.