smaller battery now won't start

OK got a 95 916 and replaced the old battery with the new smaller tz7 or whatever it is with the carbon corsa battery box. i buttoned it all up and went to go start it today after about a month on the tender and it wont' start. lights come on pump primes. When i press the starter button nothing not a click or anything. Checked all the fuses and there good.

has anyones starter button itself gone bad? is that possible or common. Or any other ideas on where i might start to look?

Starter solenoids can go bad too, and connections get loose or fuzzy on the cables.
You can short across the solenoid (usually) to confirm your starter's OK.
It'll make a good spark, so it's best to do away from combustibles.

ok i'll check the starter, is it common for it to work one day and then just go out without warning just from sitting for 1 month.? anything else i might check.

A common problem with superbikes, and older 916's in particular, is that after running fine and then shut off, it won't start again, say after a refueling stop. You don't hear a click of the starter solenoid or the starter motor turning. Sometimes if you wait a few minutes it will restart normally.

The culprit is the two-wire plastic connector plug located behind the starter solenoid (the round gold component near the battery.) The connector often makes a poor connection from distortion or corrosion. Usually jiggling or unplugging and plugging the connector will get you going again. It may be that the heat inside the fairing causes thermal expansion of the components and exacerbates the problem.

Anyway, check the electrical connector that goes to the solenoid. They always seem to fit poorly. Try zip-tying it together. Sometimes the connectors get distorted, or they just get corroded.

the bike is cold and hasn't started till right before i took the battery out to replace it with the smaller one.

Slava

I understand that. I was trying to give you a complete picture. My 916 has this problem and I suspect your's does too.

theres a white molex plug that looks like it came from the silinoide harness am i correct in assuming it goes there?

also once in awhile theres a humming comming from one of the relays with a yellow cover on it. open it up looks like a punch of copper coils wrapped up in there. turn the key it starts to hmm?

well connected the white molex plug back to where i thought it went and with the smaller battery wouldn't crank over. put the bigger one back on and cracked right up. so thinking i drained all the juice out of the smaller one. put it on the tender and will try again. atelast i know the bike started

Did you measure the output voltage of the smaller battery after charging?It seems to me very strange that with a correctly charged battery you don't hear a click...

I had the same problem than yours (no click) on both my Monster and 900SS (998 is too recent ;-)) but it was the plastic connector of the starter relay, a very classical gremlin (see Shazaam post)

ML

Sounds crazy but the rubber moulding which holds the relays was conductive on some 916 and 748 models, thus slowly bleeding the battery dry. If you replace it with a later type things often come good. I am referring to the rubber bit which is near the battery, not the one which holds the relays near the ECU.

First of all, here’s the spec for the 916 battery:

Standard battery 1994 - 2000 model years:

Yuasa YB16AL-A2 (16 AH, 200 CCA, 11.5 lbs.)

The principal advantage of using a larger battery is to be able to restart repeatedly and to deliver sufficient current to turn the starter motor. If you regularly don't ride long enough to recharge fully between restarts, stay with a larger capacity battery. A lower amp-hour battery will need to be trickle-charged more often. The chance of a deep discharge (that reduces battery life) is greater with smaller batteries. Further, the lower the temperature, the lower the current that can be supplied by any battery

So early-916 batteries are rated at around 200 CCA, the current it can supply for 30 seconds at freezing temperatures. More at comfortable riding temps.

Consider also, that the early pre-1998 bikes have an alternator with a lower charging current output, so they'll take longer to fully recharge the battery. A prolonged 30 amp charging current is one contributing factor to why Ducati voltage regulator/rectifiers and stator wires fail prematurely.

I don’t know the exact specs on the Ducati starter motor, but in general, motorcycle-size starter motors draw around 30 amps under no load (max rpm) and around 85 amps under typical starting torque loads for unmodified motors. However, this figure can briefly rise to 300 amps under a stall condition typical of the initial start requirements of a high compression motor.

In 2001, all the superbikes were fited with a revised starter motor gear ratio that drew less current and made it possible to start the bike using a smaller battery. The starter gearing on the early bikes are not well suited to the smaller batteries.

Standard battery 2001 - 200X model years:

Yuasa YT12B-BS (10 AH, 125 CCA, 7.6 lbs.)

For the later bikes, and for track use of early bikes, the weight-saving battery-of-choice is the sealed and non-spillable AGM maintenance-free Yuasa YTZ7S. It's the same size as the later stock battery.

Yuasa YTZ7S (6 AH, 130 CCA, 4.6 lbs.)

So what you’ve done is replace a 916 battery that Ducati engineers say should deliver 200 amps with a battery that delivers 125 CCA.

And you wonder why it won’t start.

If your bikes starts first crank with the big battery it will start first crank with the small battery, if both batteries are up to snuff. If the bike won't start with the little battery but starts right away with the big one the little battery is bad.