NVFRC: Ninja 250 Carb Troubleshooting

Hey folks, help please.

I just finished typing a long message outlining the problem
that I'm having and then the computer went the fritz...so
I'm going to type a much abbreviated version.

Basically I'm working on a Ninja 250 that has been sitting
for 4 years. The carbs were very badly gummed up and the
bike wouldn't run...so they were disassembled, thoroughly
cleaned, and reassembled. The float on the right bank had
stuck, emptying the entire contents of the fuel tank into
the crankcase via the right cylinder. An oil and filter
change were performed also. I did put an entire can of
seafoam fuel treatment into about a half full tank of fuel.

The bike started easily after everything went back together,
choke works fine, but the idle will hang and then slowly
come back down. It will idle at 1750 RPM easily, but only
after it has been sitting for about 10 seconds. The RPM
will hang between shifts.

I can almost guarantee it's a carb problem...but the linkage
is properly adjusted (snaps back when the throttle is
released), there are no air leaks between the carb and the
head (transom boots are tight), and I took special care that
the needle diaphragms were properly seated and that the tops
to the diaphragm chambers were tightened evenly precluding
leaks.

There is some sort of vacuum diaphragm that is attached to
the left side of the carb bank, and distributes air in some
way from both sides of the venturi on both carbs. It is
exclusively vacuum related, no fuel should have passed
through the lines, but I have a sneaking suspicion that the
problem is related to that (but I cannot be sure). I think
I should have dis-assembled that vacuum solenoid to ensure
proper operation, but since there was no fuel in those lines
I (maybe not so wisely) skipped it. It is part number 16131
in the following schematic (hope this works):

http://www.bikebandit.com/partsbandi...atic~dept_id~1
072369.asp

Thanks in advance for any advice you could provide...I'm
hoping that there is at least one person on this list that's
worked on Ninja 250 carbs (or EX500 carbs) and could shed
some light on this.

Joe
______________________
Joe Cargal
Dalton GA
Optilink account - web access only.
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I don't think anyone is paying attention (or has worked on Kawi junk before
;)...but a quick update. I just found out that the guy's bike I am working
on, has been taken apart before by his buddy. I took pictures of the carbs
before I took them apart to clean them, and I did notice that one of the
idle mixture screws was screwed all the way in. Thinking this was an odd
factory setting, I left it that way.

Turns out that the guy had no freakin idea what he was doing, and turned one
mixture screw all the way in and the other 5 turns out after popping off the
idle mixture screw plugs that Keihin put there to try and keep dopes like
this guy's friend out of a sensitive area.

At least I can adjust the idle mixture screws without having to disassemble
the bike again...just need a stubby screwdriver.

I swear...I'm sure you mechanic types get problems like this all day long
every day. I sure could charge good money doing this for a living, stealing
service from the dealerships for 3/4 price...

Thanks to all reading along.

Joe

-----Original Message-----
From: vfr-bounces@xxxxxx [mailto:vfr-bounces@xxxxxx] On Behalf Of
Joe Cargal
Sent: Thursday, September 07, 2006 8:09 PM
To: vfr@xxxxxx
Subject: NVFRC: Ninja 250 Carb Troubleshooting

Hey folks, help please.

I just finished typing a long message outlining the problem
that I'm having and then the computer went the fritz...so
I'm going to type a much abbreviated version.

Basically I'm working on a Ninja 250 that has been sitting
for 4 years. The carbs were very badly gummed up and the
bike wouldn't run...so they were disassembled, thoroughly
cleaned, and reassembled. The float on the right bank had
stuck, emptying the entire contents of the fuel tank into
the crankcase via the right cylinder. An oil and filter
change were performed also. I did put an entire can of
seafoam fuel treatment into about a half full tank of fuel.

The bike started easily after everything went back together,
choke works fine, but the idle will hang and then slowly
come back down. It will idle at 1750 RPM easily, but only
after it has been sitting for about 10 seconds. The RPM
will hang between shifts.

I can almost guarantee it's a carb problem...but the linkage
is properly adjusted (snaps back when the throttle is
released), there are no air leaks between the carb and the
head (transom boots are tight), and I took special care that
the needle diaphragms were properly seated and that the tops
to the diaphragm chambers were tightened evenly precluding
leaks.

There is some sort of vacuum diaphragm that is attached to
the left side of the carb bank, and distributes air in some
way from both sides of the venturi on both carbs. It is
exclusively vacuum related, no fuel should have passed
through the lines, but I have a sneaking suspicion that the
problem is related to that (but I cannot be sure). I think
I should have dis-assembled that vacuum solenoid to ensure
proper operation, but since there was no fuel in those lines
I (maybe not so wisely) skipped it. It is part number 16131
in the following schematic (hope this works):

http://www.bikebandit.com/partsbandi...atic~dept_id~1
072369.asp

Thanks in advance for any advice you could provide...I'm
hoping that there is at least one person on this list that's
worked on Ninja 250 carbs (or EX500 carbs) and could shed
some light on this.

Joe
______________________
Joe Cargal
Dalton GA
Optilink account - web access only.
_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

Hey, Kaws are not junk! Its the Hogs that fit that description.
:):)
If the idle is still slow to return to normal when the throttle is
closed...and the bike has CV carbs, then the slide(s) may be sticking ...or
there may be a crack/hole in the CV diaphragm.

John Harrison
Birmingham

----- Original Message -----
From: "Joe Cargal"
To:
Sent: Thursday, September 07, 2006 8:37 PM
Subject: RE: NVFRC: Ninja 250 Carb Troubleshooting


>I don't think anyone is paying attention (or has worked on Kawi junk before
> ;)...but a quick update. I just found out that the guy's bike I am
> working
> on, has been taken apart before by his buddy. I took pictures of the
> carbs
> before I took them apart to clean them, and I did notice that one of the
> idle mixture screws was screwed all the way in. Thinking this was an odd
> factory setting, I left it that way.
>
> Turns out that the guy had no freakin idea what he was doing, and turned
> one
> mixture screw all the way in and the other 5 turns out after popping off
> the
> idle mixture screw plugs that Keihin put there to try and keep dopes like
> this guy's friend out of a sensitive area.
>
> At least I can adjust the idle mixture screws without having to
> disassemble
> the bike again...just need a stubby screwdriver.
>
> I swear...I'm sure you mechanic types get problems like this all day long
> every day. I sure could charge good money doing this for a living,
> stealing
> service from the dealerships for 3/4 price...
>
> Thanks to all reading along.
>
> Joe

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