Anyone else have this problem?

I went for a ride yesterday on my Kawasaki VN800B Classic. I was less than
two miles from home when I came to a four-way stop. I was still running a
touch of choke. The bike has just over 750 miles on it.

Bad idea
After starting and a 30 second run, you dont need to choke it
"Choke" is only for starting.

Sorry, not on some bikes, no.

You would have to wait twenty minutes to a half an hour before being able to
ride if you didn't use partial choke. This one is really, really set lean.

The cold-blooded nature of your Vulcan is easily solved. Simply follow the
instructions I have posted a bazillion times about drilling out the EPA anti-
tamper plug and turning the idle mixture screws clockwise between 1/4 and 1
full turn.

I can't find the exact idle jet size, but it will be between a #35 and a #42.
Since the area of the orifice hole = pi times radius squared, you can see
that that the #42 idle jet has an area of 1.44 times that of the #35 idle jet.

So the initial factory setting on a carburetor with a #35 idle jet might be 2.
5 turns out and the initial setting of a carb with a #42 idle jet might be
less than 1/4th of a turn out.

I'm having trouble following this arithmetic. Is there an approximate
formula for deriving 1/4 from 2.5? (Being maybe too crude about it, I
would have guessed an approximate number of turns for the bigger jet of
2.5/1.44 = about 1 3/4 turns.)

Changing the size of the idle jet may change the area of the idle jet's
orifice exponentially, but it doesn't change the area of the orifices in the
carburetor body.(1) All carb bodies for a particular series of carbs would
be drilled the same, then different jets would be screwed into the body.

If the idle port and the three transition ports are all the same size, the
idle mixture screw controls only 1/4th of the total flow that can go through
the idle jet.

The typical range of idle jets found in CV carbs have orifice diameters of
0.350 mm, 0.375 mm, 0.400 mm, and 0.425 mm.

There are some general rules of thumb for setting gas screws.

If the idle screw has to be turned out more than 3.5 turns, the idle jet is
too small.

If the idle screw has to be turned out less than 1/4 of a turn the idle jet
is too large.

If a professional racer is on the season tour, his crew chief might select an
idle jet that is of a size that allows him to turn the screw 1.5 turns either
way to compensate for altitude.

An amateur racer who only runs at one track might be perfectly happy with an
idle jet that had to be set at only 1/4 turn out or 3.5 turns out.

More rules of thumb:

If you go one size larger on the idle jet, you will turn the fuel screw in
about 1.5 turns to achieve the original idle mixture.

If you go one size smaller on the idle jet, you will turn the fuel screw out
about 1.5 turns to achieve the original idle mixture.

(1) Dynojet probably takes this fact into account when they make up a kit
with slightly smaller diameter needles so they can use needle "drool" to
richen up the
idle circuit.

cheers,
p

92066: PLUG,PILOT SCREW,[CA,US] (EPA anti-tamper plug)

16014: SCREW-PILOT AIR (It's really a pilot GAS screw, turning it
counterclockwise richens the idle mixture and eliminates the cllod-blooded
nature of the motorcycle.)

92063: MAIN JET,#140,(OPTION)

92064: JET-PILOT

92063A: MAIN JET,#135 ,(OPTION)

92063B: MAIN JET,#138,(OPTION)

92063C: MAIN JET,2ND,#130,(OFF ROAD USE ONLY)

92063D: JET-MAIN,#132,(OPTION)

idle and cruise

Ed Cregger

I began pulling away from the stop sign when the bike suddenly locks up,
nearly tossing me over the handlebars. My feet stayed on the footpegs, but
before I could get my foot down, the bike and I fell onto our right side.
The bike was cushioned from the ground by my body, so it wasn't hurt.
Neither was I.

I could swear that the transmission locked up. I realize that it could also
have been a cold engine quitting, but it didn't feel like that, if you know
what I mean. When the bike and I were both upright again, I couldn't get the
transmission into neutral, even when rocking it back and forth with the
clutch out until after a few minutes. Then it finally let me pop it back
into neutral.

I have had transmission problems before, but they gradually went away as I
accumulated miles on the bike. It would occasionally pop out of second gear
and sometimes would give me a hard time when trying to find neutral. As I
accumulated miles, the problem disappeared. Then we had the first oil change
and the problems have begun all over again. This latest trick is something
new and not something that I wish to repeat again.

The bike is out of warranty.

It's out of warranty because its more than 12 months old, right? You don't
ride it much because you're not into the "cruiser thing"?

I suspect two possibilities which explain what happened.

The first is that the starter clutch engaged because the engine was idling
too slow. This backdrove the starter and it was hard to get the bike into
neutral because the crankshaft and starter were jammed up. I had this happen
on my old GT750 water buffalo and had to push it half a mile home, while
holding the clutch lever in.

13194: CLUTCH-ONEWAY (It looks like a Sprag clutch, which is like a roller
bearing with egg-shaped rollers that don't roll, they either jam up or they
slip.)

42034: COUPLING

The other possibility is that you didn't quite shift far enough to get into
first gear, and you slipped into neutral with the help of Kawasaki's
automatic neutral finder.

With the sudden loss of power to the rear wheel, whatever force you were
applying to the handlebars to hold the bike upright suddenly levered the
motorcycle over onto your leg.

92143: COLLAR

600: BALL STEEL 5/32''

13128: SHAFT-TRANSMISSION OUTPUT

The transmission won't shift gears very well if the bike isn't moving.

The collar moves the steel ball sideways, and it falls into the hole in the
output shaft. The automatic neutral finder rarely fails, but when it does,
the transmission is jammed in first gear.

Any thoughts?

Sounds like a badgered gearbox, doesn't it?

So... fix and keep, fix and sell, or sell without fix. Your call.

Come on, Neil, you didn't bite!

"The bike has just over 750 miles on it."

Ed Cregger