Armchair diagnostics- hard warm start

[John Soliday]

Weak battery sure can do what you describe!  If your multimeter was correct,
the battery is dying, it should read 12.6VDC minimum with no load.  What is
happening is your battery voltage is probably dropping enough while cranking
that the brain box or coils are not seeing enough voltage to spark.  I'm
thinking it's the brain box as you're getting zero spark unless you have a
fresh full charge or a jump start, all signs of low voltage during cranking.
I bet you get a new battery and all will be fine.

John

-----Original Message-----
From: gpzlist-bounces at micapeak.com [mailto:gpzlist-bounces at micapeak.com] On
Behalf Of Don Wilcox
Sent: Monday, April 12, 2010 10:32 AM
To: GPZ List
Subject: Re: Armchair diagnostics- hard warm start

Update:

As of yesterday, carb idle screws have been reset to 2.5 turns out across
the board (with the assistance of the Mrs. and a number of 4 letter words).

Now I see why you guys always said the GPZ is so smooth... OMFG... perfect
fuel metering right at 4000rpm, smooth pull from 3000 to 9000. No hiccups,
almost no burble on the deceleration. Wow. I started it with one stab, and
was able to turn off the choke within 10 seconds. Hasn't been like that in
years.

BUT... it still won't start after being run. Turns over with vigor, but
won't fire, dammit. Tried so long I did weaken the battery significantly,
but no dice. Ended up jumping it off a buddies truck, and first stab brought
it to life with no drama.

Took it home, and tried to restart (still *sounded* like it was turning over
strongly), but nothing. Put it on the charger, and BOOM, instant start with
no drama.

I then pulled the battery, puled out the multimeter, and it showed 12.35VDC.
I then did what they say NOT to, ie: pull the caps and top off the battery
with distilled water. It was significantly low. Slapped it back on the
charger (at high amp) for a couple of hours (checking for boiling battery
syndrome every half hour). Unfortunately, my multimeter croaked yesterday as
well, so original reading of 12.35VDC is suspect as well.

I tried starting this morning on a lark, and although it turns strongly, no
vroom. I did look a the battery, and I dont' remember buying a Yuasa in the
last 10 years, so I'm pretty sure that I HAVEN'T replaced the battery in the
last 5.

Would a low battery still be able to spin the starter with authority, while
NOT being able to start the bike? Or am I goign to be chasing a different
gremlin?

Don in GJ