97 VF750C hard starting

 

So I woke up yesterday and realized I had not put my bike in the shed
that night.  It was a bit chilly, maybe 38 deg f.  Normally I just
crank it up and crack the throttle a tiny bit until it smooths out.
Not yesterday.  It wouldn't idle, and giving it any throttle at all
flooded it.  Choke flooded it.  My choke is very touchy anyway.  Well,
I finally ran out of time and just put it up and drove the truck to
work.

When I got home at 5 I pulled it out and still had the same problem.
Finally turned my idle screw in a few turns and she fired up, but she
was only on 3 cylinders.  I ran it at a high idle for a little bit,
still on 3 cylinders.  Then I drove up to the auto parts store about 3
blocks and got some Sea Foam.  Put a liberal amount in the tank and
took off.  About 3 more blocks and the fourth cylinder kicked in.  I
took it for a 5 mile jount then parked it.  This morning started up
ok, but only after turning the idle in a few turns again, but she is
on all 4 cylinders and smoothed out pretty quick so was able to idle
it back down to normal within a couple minutes.  

Do my carbs need sycronizing?  Just something to deal with?

The plugs are only a few months old and are what the dealer recomends.

--
The Cross-eyed Barber

 

The Cross-eyed Barber wrote:

Your Magna doesn't have a choke. It has a starting enrichener, which is a
little valve in an air passage that bypasses the throttle butterfly. When you
open the little valve by operating the choke lever or knob, the engine sucks
gasoline straight out of the float bowl through the starter jet.


If you mean the idle speed screw, turning it counterclockwise a few turns
closes the throttle butterflies and they close off the acceleration
transition ports, so the choke works right again.

Also, your Magna has #40 idle jets, which are rather large. So the idle
mixture screws would have been set almost fully closed at the factory, before
being concealed by the EPA anti-tamper plug.

At some point, the idle jets and idle ports started plugging up with gum and
varnish and the engine began stalling when the rider decelerated. So somebody
probably adjusted the master idle speed knob, and that uncovered the
transition ports, so the engine ran off of them, instead of the idle mixture
ports.

That explains why the engine floods so easily when you give it full "choke".


Sea Foam is just thin oil and naphtha. It is for fogging 2-stroke outboard
motors to keep them from rusting inside. The rod bearings in a 2-stroke are
ruined by rust when moist air condenses inside a 2-stroke's crankcase.

What you really want is Berryman B-12 Choke and Carburetor Cleaner to clean
out the idle jets and idle ports in your carburetors. Add about 5 ounces of
the liquid B12 to a full tank of gasoline and go for a ride.


No. Synchronizing carburetors is a money making scam that lines the pockets
of the mechanic$ at the $tealer$hip. Your carburetor linkages and throttle
butterflies will not wear out enough to require synchronization before the
motorcycle has 100,000 miles on it.

Synchronizing was required on older motrocycles with slide valve carburetors
and throttle cables, but modern CV carburetors don't wear out, they plug up
with gum and varnish and the $tealer$hip mechanic$ advise riders that their
carbs are out of synchronization.

If the carburetors aren't chemically cleaned with B12 or STP or GumOut carb
cleaner before synchronizing them, the alcohol additives in fresh gasoline
will clean out the the idle jets and passages and the motorcycle will run
rough again, because the mechanic messed with the synchronization.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200710/1

 




Well, you already have been told everything you ever need to know about
carbs so I won't go there.
I do agree that Seafoam is not good for cleaning a carb that is already
gunked up.

Let me throw out another wild idea:
Was there dew on the grass?  If so, there probably was moisture on and in
every part of the bike too.  You may have been losing spark in that one
cylindar because of arching across a damp (something).