advice please: bike troubles

[Duke of Rogan]

before I take my bike to a shop and have the wrong thing fixed, I'm hoping the brains-trust that is KB can give me some quick advice on a couple of problems with my bike (I've only had it 3 months and yet to take it to a workshop).

1st problem: bad battery or bad charging?
I've had to recharge my battery a few times now, and last time I gave it a full overnight charge, which has lasted over 2 weeks I think, but I noticed this morning it was slow to start.
How can I test if the battery needs replacing, or if my bike isn't charging enough? I have a multi-meter and have measured the voltage across the batt with engine running (idleling), I think it was only about 12.9V and the batt itself when off was about 12.5V
I suspect the battery needs replacing...

2nd problem:hestitation and rough response at certain revs, espically when cold and worse with 91 octane gas.
Other symptons:
- not very good fuel economy (approx. 100kms / 6L or 7L)
- sometimes backfires when starts (esp. with 91 octane!)
- hestiation at same point in rev-range (about 4800-5000 RPM)
- terrible in 1st gear / low revs when in traffic (pops a bit)

Things replaced/done already:
- new spark plugs (old ones were a bit sooty, news one have got carbon on them too, suspect mixture too rich?)
- new K&N air-filter (had OEM paper one)
- balanced carbs, adjust idle and mixture a little. (had a mate do this, owns the proper gauges, did help a little)
- replaced fuel filter

Possible solution:
I suspect the jets need replacing. Mixture reset, carbs balanced again.

the bike has had the OEM jets replaced with a stage 1 dyno-jet kit, but that was when it was new-ish (1st owner, 300kms). I am the 3rd owner and its about to do 30,000kms.

all advice except for trading it for a different make is welcome

[MikeL]

Duke:
2 questions about your battery/charging system:
1. how old is the battery? The older it is, the more likely it's the problem.
2. have you got your bike's workshop manual? If so, what does it specify as the charging voltage? I think 12.9 is a bit low. For my Honda, the regulated voltage at 5000 rpm should be 14 - 16 V. Could be a fault in the regulator/rectifier or the alternator.

[Duke of Rogan]

I'm not sure about the battery's age and I'll have to research the charging voltage (dont have workshop manual).

[ScottieX]

Try one thing at a time. You may find that the battery ( if it is suspect ) may be causing other symptoms to be apparent.

My unknowledgeable two cents worth.

[bikerboy]

I know nothing technical about bikes but read about and had a similar battery problem on my previous bike.

Now, the bit that charges the battery if often defective on ducatis. This prevents battery being fully recharged. Engines require a lot of batt power to start, and eventually need new battery. I replaced mine three times over four years. This defect just wears them out.

Check out www.clubdesmo.com lots of posts about ducati battery problems.

[Duke of Rogan]

thanks all for your help, I think i'll replace the battery then see how the motor runs.
I found a thread on the clubdesmo site titled "Rough engine with a bad battery", in which someone reported that replacing the battery fixed the rough engine, however I think this is on an injected bike with an ECU, and mine is carb'ed.
I tested the charging voltage again last night, and without the headlight on it got up to about 13.8V and with light on 14.0V
With the key on and only fuel pump running, the battery voltage quickly dropped below 12V, so again I suspect its not very good.

[wkid_one]

What plugs you running?

I found that with the twin - any poor spark was much more noticeable.  Since fitting high performance plugs the bike runs a lot smoother.  Cost a bit more - but well worth it in the performance stakes.

 

[Duke of Rogan]

What plugs you running?

not high-performance ones, unless they were on special for $5 each
I got them from Haldanes (ducati shop), I think they are NGK...

it could weel be spark related, according to clubdesmo post the "bad battery" can lead to poor spark. Think I'll try and get another battery this week.

[MikeL]

With 14V coming out it looks as if your alternator and reg/rec are O.K. A new battery is in order!

[What?]

Yeah, but before you rush out and buy a new battery, just check that the earth strap is solid where it meets the frame, and also the earth strap between engine and frame (if there is one). Could be a poor earth is causing a big voltage drop which is making the CDI unhappy. I would expect the fuel pump to quickly drop battery voltage below 12, but it should stay well above 10 volts for quite some time.

[scumdog]

Duke the guys are right, get hold of a new battery and give it a go, it's amazing how many "problems" a good battery can "fix" plus if you try that first then you won't have nagging doubt when you have other bits apart that maybe it was the battery.

[scumdog]

Duke, just an after-thought, your scoot seems REAL hard on batteries, my last one lasted over seven years and then I sold the bike, for all I know it could still be working.
If I am not using the bike for a bit ( i.e. away for a while) I put the battery on a slow charger, you just got to keep an eye on the water, then when you go to use it again it'll fire up easy.

[wkid_one]

I don't think that he is worried about the battery now

[Duke of Rogan]

Originally posted by wkid_one
I don't think that he is worried about the battery now

too right. maybe I can tack a new one into my insurance claim...

[bikerboy]

Maybe you can get the whole thing sorted as a result of the accident.

"Gee, it ran fine before the accident but now seems to run rough and the battery is shot"