yzf 450 bog in carb

[blyski]

Well... I have about given up. I have read all the comments on how to fix a bog in my bike. The problem is when I hit the throttle the motor falls on its self. It will shut down or back fire at best. I have changed jets from 152 to 175 GYTR with 45 or 48. I have also changed the slow or leak jets to 35 and 40 as recomended. I have moved the pin clip up and down so many times I feal like a kid dressing up a doll. In the end the only time I saw any improvement was with a 180/ 48 GYTR combo but it ran so rich it would not run well. O yes, I have used every air jet setting I could find. In fact the air jet appears to change nothing fully open or closed.
I was even willing to pay Yamaha to help with nothing to show but a $350 rip off from Simi Valley Ca Yamaha.
If anyone has and other ideas or even a good mec I could pay for help please please help... next step for me is a different machine if I can not get fixed. thanks

[KH426]

What set up are you running?

[Splatter Matter]

check you stator & rectifier . flywheel if its not stock the magnets like to crack and give false single. you might thinks its jetting and its not. here is how to check

Unique Charging System Characteristics - Yfz450
The YFZ450 Charging System is designed to
supply at low to medium engine rpm a maximum
charging rate with the headlights in the
ON position. Under some conditions (e.g., low
speed with cooling fan running frequently or
continuous high rpm riding), it may be necessary
to ride with the headlights in the ON position
continuously to maintain a fully charged
battery.
If a customer complains of the battery discharging
while riding, first check the condition
of the battery.
NOTE: If improperly charged or boost charged,
these compact batteries could overheat and
become permanently damaged. To prevent
overheating, charge the battery using a low
output charger (e.g., Optimate III, ACCOPTIM-
AT-E3), and test the battery to make
sure it is in good condition. Next, Check the
output of the charging system.
To avoid mis-diagnosis, follow these procedures
and specifications in the order below:
1. Minimum key off (battery voltage must be
12.80 VDC).
• Voltage too low: recharge and load test
the battery.
2. Measure the battery voltage at idle. *It
should be 14.0 ~ 14.9 VDC before the cooling
fan starts to cycle ON and OFF.
• Voltage too low: check the stator coil
resistance. The correct specifications
are:
– Yellow to Ground = 0.22 ~ 0.60 ohms
– White to Ground = 0.29 ~ 0.84 ohms
– Out of Spec: replace stator assembly
• Voltage is too high: check wire continuity
(particularly the black wire which
should have continuity between the
Ground). The Yellow/Red wire should
have continuity between the lighting
coil and the regulator.
NOTE: If continuity checks good, replace the
regulator assembly. (Commonly, both headlights
are burned if the regulator has failed.)
• Voltage Okay:
–
–
–
NOTE: Do not check the battery voltage at
5000 rpm as explained in the Service Manual.
Charging output will decrease as rpm increases.
This is a normal characteristic of this
model.
*Since the system normally discharges anytime
the cooling fan is ON, all testing must be
done before the fan starts to cycle on and off.
Otherwise, the maximum measurable battery
voltage will be lower than 14.0 VDC.
SUBJECTS: 1. Unique Charging System Characteristics - YFZ450
2. Introducing YFZ450 Charging System Resistor Kit -
Resistor Kit for Competition Usage
3. YFZ450 Resistor Kit Installation Instructions

Check the radiator for blockage and
correct as required.
Advise the customer to use the key
switch to turn the engine off. Only
use the engine switch (on the handle
bar) in an emergency.
Advise the customer to switch the
headlights ON to increase the charging
output.
Introducing YFZ450 Charging System Resistor Kit -
Resistor Kit for Competition Usage
Symptom:
As explained in the previous subject (page 1),
the YFZ450 Charging System is designed to
supply at low to medium engine rpm a maximum
charging rate with the headlights
switched to the ON position. If the headlights
are removed for competition use, the unit may
experience battery discharging.
Remedy:
Install the YFZ450 Resistor Kit. The kit contains
a ceramic resistor which takes the place
of the headlights to maximize the charging
rate, plus it provides a higher temperature fan
thermoswitch to minimize current draw. The switch is
located sitting on the bike the upper right switch
NOTE: This higher temperature is still low
enough to not cause engine overheating.
The kit is optional for competition use and warranty
does not apply. The kit was developed to
allow maximum charging and reduce battery
load.

[intruder]

What year is the yfz?

[blyski]

The bike is a 2004 set up with a GYTR slip on and a K&N air filter conversion. I live in So California and ride in the sand and low elevation. I don't think its the chargeing system as I see no differance with lights on or off and have not changed any thing from stock. Thanks so far and I look forward to any help from others.

[bullet3z]

It sounds like you are way to rich for sea level and just a slip on. Go back to stock and start from there. Go up 1 jet size on the main and 1 jet size on the pilot. Then set the fuel screw at about 2 turns out. Leave the #35 leak jet in there and see what you got. The idle needs to be set high, over 1,000 rpms per the service manual.

While rejetting write down every change you make so you can go back if you have to. Also what needle are you running? Is it the NCVQ?

[blyski]

I do have the NCVQ needle in, I will try your recomendation and let you know. 165 and 42 I think? Thanks

[racerxxgncc]

Put the stock needle back in and I bet you find your problem.

[daddio]

Mabey you're just stabbing the throttle too fast. When I first got my YFZ, I was hammering the throttle just like I did on my Banshee. I also went through the "jetting woes" like you have, without much improvement. Then I turned my idle up a little and learned to ease into the throttle a little bit more.
You might also check the setting on your accelerator pump cam.

[Pitboss45]

same thing happened to one of our riders.

found out that the spark plug coil was cracked ever so slightly causing his ride to react like jetting problems. this was changed and all the problems went away.

you might have other issues, but not many people will check this.