Dead Tach help

[Do Lee]

Last week my tach also died on the way home from work, did the checks and the A. C. generator turned out bad was running on battery only. Replaced stator and field coil and tach now works and charging is around 13.5+ volts. So I would also think that your tach has probably gone bad.

[gnevelesx08]

Thanks for all the info guys. I finally did the Ebay war for a new (used) Tach. I thought it would be more fierce of a fight so I bid on two auctions at the ame time. Both bids were on a full set of gages for a 78 standard. I won both sets! It was unexpected but then it may be a good thing! I received one set today and installed both the tach and speedometer. MY TACH IS WHAT WAS BAD THE NEW TACH WORKS PERFECT. The new 180 speedometer is another thing. I did a search for threads on the speedometer and found out the 180mh works with the 80G (thought I might need a different cable drive) so now I have to figure out whats wrong with it. It's slow to climb and fall reads 20mph when I know I'm doing 60 or 70. I hit 80+ mph and it jumps to read correctly. It probably needs cleaned and lubed. I rechecked the cable three times to make sure it was installed correctly. I will lube the cable first and also try some how to do a lube through the back of the speedo. I have another one comming so I hope its a good one. I saw on another thread some picks of a disassembled xj speedo. I hope to do surgery on te bad tach and will try to post some pictures. THANK YOU ALL FOR THE HELP.
Dan

[gnevelesx08]

Before I get Everyone all excited its a 160 mph speedo not 180. I gues I just want to go faster!

[Shuriken]

My 79sf tach is still dead. Haven't replaced it because I didn't want to war with everyone else who also seems to be needing a round tachometer.

Anyway, while riding it for a couple hours, I noticed the needle will bounce up to about 2k rpms occasionally. It's not vibration that moves the needle. I think it's got a bad ground somewhere or something like that. I think the road bumps and stuff cause the faulty circuit (wherever it is) to work for a split second.

Ben

[tribaltalon]

man my tach bounces around too upwards of 4k. i dont know what it is.. could it be a bad rectifier/regulator? as far as i know its charging the system, i've put over 1,000 miles on my xs now and its running fine.. just seems to run a little rough and the tach bounces. i think the running rough part is just due to the carbs though, i need to get them cleaned out and synched.

[Shuriken]

Replaced the tach that was not working and the new one works fine.
Ben

[chevy45412001]

electric cleaning

while going through much the same prbs latley i went to radio shack and bought there brand electrical cleaner in a spray can. the reason being it has a built in cleaning brush that is very small on the tube of the can. it works really good IMHO. its small enough to fit inside the connectors when you unplug them and can actually scrub around to clean them well.

[backroadspecial]

tachometer jumpy and inaccurate

I have a 1980 XS1100LG and am finding the tachometer malfunction to be a very frequent problem. Mine will occasionally show 3500 RPM in 5th at 70 mph and the other times 6500 RPM in 5th at 70. It also will jump around frequently between 0 and 8000 RPM and has gone to 0 twice for about 5 seconds. I have pulled stator (all looks good), cleaned all connectors (they all were clean anyway since it is always garaged), and checked voltages (blk to brown 12.5 v DC and white to black 7 V AC). My confusion is this: the tachometer picks up pulses from one leg of the stator and when tested at the connector gives a 7v AC output (normal output per the service manual). Therefore, because it is an AC voltage, it does not go through the rectifier (whose purpose is to convert AC to DC). The white wire coming from one leg of the stator is T'eed off to the tachometer before it goes to the rectifier. So, with a jumping tach needle and a verified operational charging system (12.5 v at battery not running to 14.5 v @ 2000 RPM), the only thing left that I can think of is a break in the wiring which connects together with vibrations from the engine.
Looking for a wiring defect is tedious to impossible. Wires coming out from behind the AC generator cover are held by a bendable tab to keep them away from the exhaust and they make a sharp bend. If I were to guess, this is where I would suspect a break, however, I hate to break through factory wire-protected loom on a hunch since it opens that wire to corrosion.
I need further help from others to sort out the problem, since I am at a dead-end.
Not mentioned above: 1st tach was sent out for repair due to occasionally staying at zero while on the road for 10 seconds and was returned to me after repair work totally inop. The tach I am referring to above is an NOS tach from an e-Bay seller.

[cajun31]

most

if not all of us experience what you are describing. Have you looked at this thread in the repair section http://www.xs11.com/forum/showthread.php?t=68? The puzzling thing for you is you have stated that you are on your second tach. If you bought it from an ebay seller it is probably just as old as your original with the same problems. Mine is the original and bounces a bit but I don't let it bother me. I pay more attention to the speedometer and what is in front of me.

[backroadspecial]

Thanks, Most. I saw that thread and have decided not to blindly squirt anything like WD-40 into the tachometer hoping that God will help to cure the problem. If you know WD-40, it may help for a day and then dry up & become a sticky mess (something you don't want to happen in a tach). With me, if I don't have a well-defined cure, I won't do anything, as more often than not, it causes things to get much worse (like ruining another tach).

[bikerphil]

I have had to disassemble the tach and re-sweat the solder joints on the board inside to get it steady after trying everything else. YMMV

[3Phase]

Backroadspecial,

The wires coming from the alternator stator are steel strands with high-temp woven insulation, not plastic, so the wires are not likely to break but it's not impossible. Once you have the pigtail disconnected from the harness and out of the wire guides on the engine they're easy to check without taking them out of the factory wrapper.

The splice in the main harness and the White wire that goes up to the tachometer from the 6-pole rectifier connector is also not likely to break and it's easy to check too. The wire is mixed into the rest of the wires in the harness enough that you can't just pull on it from the tachometer or the rectifier connector so you do have to slit open the harness and follow the White wire to the splice.

The 1980 or later XS1100 or XJ1100 has a second White stator wire and splice that goes to a diode and the Headlight relay on the XS or the Computer Monitor on the XJ so make sure you've traced the correct wire before you declare victory and wrap it up.


If the tachometer is still having problems after checking the harness wiring and double-checking the 4-pole Stator/Harness connector under the right-hand side cover then it's a tachometer problem.

Unfortunately, the tachometer is a sealed unit with no user serviceable parts inside so you have to refer servicing to qualified personnel -- which you already did -- or you can remove the front bezel and try to repair the tach yourself.

If you decide to repair the tachometer there are two types of failures to look for: electrical and mechanical. Electrical problems require repairs to the wiring or the circuit board and components; mechanical problems require repairs to the 'motor' for the tachometer needle itself and that is more fun than several barrels of monkeys.

Personally and after doing both types of repairs myself I'd shop around for a working tachometer while I had a some serious dialogue with the qualified personnel that broke the broken tach and the eBay seller about that NOS tach.

.

[backroadspecial]

3Phase,
Thanks for your detailed reply.
Motorcycle instrument repair is not my bag. I have looked at forums where people have taken the thing apart and then say where do I go from here as I don't know how the thing ticks and I have no parts to substitute in. So, I leave that part to people in the business. I searched for people who repair electronic tachometers and found only West Valley Instruments in Reseda, CA (do not use this repair shop!). The first repair I got from him, the tach was reading 2x engine RPM. So, I sent it back for adjustment and received it a few days later with no movement of the tach needle when hooked up & running. Despite the warranty, he refunded me only half the labor price, plus I was paying all the shipping costs at $15.00 x 4. Two other instrument repair shops I have used only work on cable driven tachs and one cracked the faceplate when tightening the screws as the faceplate was wobbling. In short, I do not want to tackle tach repair and I don't know who to use in the repair business since all 3 I have used have been losers.
At this point, the eBay NOS purchase is all I have available and seem to think it would be more repairable than my first one given that I could find a dependable & honest repair shop.
Still looking for advice and help. Might be better off purchasing another used unit from an eBay seller, however everything is 30+ years old at this point, so it is possible all of these would need some kind of repair &/or lubrication.
Question to ask: Is the AC voltage to the tach supposed to vary depending on engine RPM? The book says 5-7 VAC and I get from 7 to 9 VAC (9 vac when running at 2000 RPM). Is there a problem here or is that normal function?

[3Phase]

I'm almost next door to Reseda

The Regulator/Rectifier is doing its job. The AC varies with engine RPM up to a point that is determined by the Voltage Regulator. The Voltage Regulator regulates the voltage and the Voltage Rectifier rectifies AC to DC.

So get another tachometer BUT make sure the wiring harness, the connectors and the Regulator/Rectifier are in good condition.

Check and clean the alternator Field Coil connectors to make sure they're working. There is a 3-pole connector with Brown, Green, and Black wires at the Voltage Regulator. There is a 2-pole connector with just the Brown and Green wires and it's next to the Stator connector under the right-hand side cover behind the fuse panel.

Just for grins, here's a link to how the tachometer is made:-


Inside The Tachometer


Are you sure you don't want to slice 'n' dice a tach or two?

.
.