Tach-twitching and going out completely

[fouramdesigns]

yeah I was there Friday. Man this bike is a money pit. I have no clue what these gremlins are, but I wish we could work them out for once and all.

[junior varsity]

You could just rip all that nonsense out and put in some aftermarket gages

[fouramdesigns]

it's not the battery. I just put the Yusa in Wed. This morning, battery is dead. So I'm guessing alternator etc. It never ends with this Duc. I'm taking it to Alain, telling him to keep it till we figure out what electrical demon is in this bike. I'm tempted to sell it, but I'd maybe get 3K right now. Any suggestions as to what electrical may be going on here? I've tried to describe the symptoms in detail. 

[junior varsity]

Can we rehash the symptoms:

You ride it, it performs fine?

While riding, the tach was twitching, or failing to register below a few thousand RPMS
Then the Tach just quit?

Sounds like wiring to me. Possibly corroded? And either some short, or moisture in some connections that would trigger the blinkers/tach. I don't have an S4 to go look around at to help you, since its quite a bit different in cluster setup than my M900 (which didn't come with a tach, and I had Alain put it in before i decided to start doing things myself, getting it wrong, and then having him fix them )

[fouramdesigns]

rough start, odd idle, exhaust sounds odd, tach issues, rough power band. And of course now, my new battery is dead.

[junior varsity]

charging system, and/or pickups not picking up the revs would lead to poor tach output / horrendous idle. Like if one went out, bike might run on one cyl, tach act funny, etc.

Good thing is its in capable hands, for sure.  Bad things is that sometimes odd problems come from places that don't immediately jump to mind.

[fouramdesigns]

Pick ups?

[junior varsity]

Yeah, for the ignition. To tell it to go bang.

[fouramdesigns]

Ah young chap. Alain even thought maybe ECU.

[junior varsity]

Might be worth finding one on another bike to swap in just to try it.

[darkduc7]

i had a very similar situation on my former monster. i really am suspecting wiring to the coils because the tach is no worky and the tach runs off one of the coils. and it would explain the roughness. now, it definitly could be pickups as well, good call on that ato memphis. if it was the altenator, i would suspect the bike would run fine for a bit and then die as the battery lost charge. so i doubt its the altenator since the bike just plain sucks at all times. also, check if your rectifier/regulator is working. take a multimeter and check the voltage at the battery terminals with the bike not running and then when running. it should spike to around 14v running.

[darkduc7]

my problem had the same symtoms... and it was a loose/corroded connection on the bottom of my left coil. it caused no tach, rough running (one cyl), and would occasionally ground out and kill my battery.

[fouramdesigns]

darkduc, great info, ATO,  thanks as well. I'll pass on to my mechanic. I don't have a multimeter, too many irons in the fire at the moment. Rugby, trying to buy a car, work schedule etc. But thanks for the great leads.

[darkduc7]

your regualtor should be hot/warm to the touch too, that means youre getting charge from the altenator system, and that will kinda rule out that variable.

[junior varsity]

also, remember Alain likes a good cigar.