Question about 2001 Yamaha YZ 426 F

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My bike has a low end bog im looking to tune the fueling. how do i do this?

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  • Yamaha Master
  • 41,856 Answers

Hi, Brennanhales it should be noted that your performance issues are not electrical ie. faulty charging system, battery condition, and connections etc. If your fuel system (gas tank, filters, fuel valve and carburetor) is contaminated with ethanol sludge, varnish, rust, dirt, water etc. or your bike has been sitting for months or years without running these components must be "PROPERLY" cleaned and reassembled "CORRECTLY" before any adjustments can be made. Tuning your carburetor is fairly simple once you understand the basic principals. You engine is a simple airbox sucking air in and blowing it out, it is finely tuned at the factory for maximum performance once you upset that delicate balance by changing air filters, camshafts or exhaust systems your performance may go down the and the engine may run poorly, you need to compensate the air-fuel mixture in the carburetors in order for the engine to run smoothly and at peak performance. If you are running multi carburetors you need to sync them first and make sure your air cleaner element is clean and dry for paper elements or lightly oiled for foam and meshed elements and properly installed. Here is how and where you compensate trouble: "TIP" if your engine "BOGS" your not getting enough fuel.
1. Closed to 1/8 throttle is managed by the air screw and pilot/slow jet.
2. 1/8 to 1/4 throttle is managed by the air-screw, pilot/slow jet, and throttle slide.
3. 1/4 to 1/2 throttle is managed by the throttle slide and jet needle.
4. 1/2 to 3/4 throttle is managed by the jet needle, needle jet, main jet, and air jet.
5. 3/4 to wide open throttle is managed by the main jet and air jet.
6. Wide open throttle is managed by the main jet.
If you are running lean, spark plug electrode color is white, engine runs hot and feels like it is starving for fuel you need to go up on the jet size or move the c-clip down one notch. If you are running rich, spark plug color is black or dark gray, engine runs cool, and bogs down when accelerating you need to go down on jet size or move the c-clip up one notch. When your carburetor is properly tuned for maximum performance your spark plug electrode will be a light tan color like coffee with cream. If you prefer fuel economy over performance you can go down on main jet sizes until a satisfactory level of lower performance is acceptable versus MPH, your spark plug color will be whiter and your engine will run warmer. These tuning adjustments will only make improvements if your intake and exhaust system have no air leaks or sealing issues and the entire electrical system is in proper working order and you have no mechanical issues. For more information about your issue and valuable "FREE" downloads that you will need please click on the websites below. Good luck and have nice a day.
Carb tuning on yz250f swivel technique
How To 4 Stroke MX Fuel Screw Adjustment YZF CRF KXF RMZ FCR Part 1 of 2
Yamaha YZ426F Owner Service Manual
OEM parts for Yamaha
Yamaha YZ450F Owner Manual Page 3

Posted on Aug 08, 2016

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Posted on Jan 02, 2017

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SOURCE: I have a 125 kaw kx 2 stroke good power on low end

Pull the slide out and then move the clip on the jet needle one notch lower. Also try two notches to see which helps most. This will richen the mix in mid-range.

Pleas rate thia answer. Thanks v222407! :)

Posted on Apr 15, 2009

ollie reece
  • 1167 Answers

SOURCE: Low-end Bog

tried this on the carb turn the mixture screw in a 1/4 of a turn

Posted on Oct 09, 2009

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bazzz7071
  • 338 Answers

SOURCE: 2001 kx 85 has sever low end hesitation. I can't

Hello you have a
1. fuel starvation problem clogged carburetor jets.(clean the carb)
2. Intake leak carb joint/intake manifold.( start your motor get it to idle best you can spray wd40 around the carb joint if the rpms change you have a leak replace the carb joint or gasket/o-ring as needed.
3. crankshaft main seal magneto side leaking or worn main bearing.
check end play on the magneto side remove the cover plate firmly grab the end of the shaft with up an down motion if you can feel it move replace the main bearings and seals.
These are problem that will cause your motor to run lean and hesitate.
Hope this helps you with your problem

Posted on May 10, 2010

  • 22 Answers

SOURCE: low rpm boging,just did complete tune up replaced

How many miles? How's the compression? Could need rings. Running good fast/poorly slow is symptom.

Posted on Aug 11, 2010

MNfisherman
  • 11896 Answers

SOURCE: If I'm low on coolant will the bike bog down and

She will loose power and possibly shut down if overheated. Check your cyclinder pressure. Make sure head didn't warp.

Posted on May 14, 2011

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I have a 97 jep cherokee country 4.0 and can't find the fuel filter...my jeep acts like it's not getting.gas and wants to put? when im going 60 or so and i changed the fuel pump but its still doing it


if you follow the fuel rail gas line, it goes to the filter.
for sure.
4.0L 97 , we have the FSM to see all that , ive posted it 100s of times here. that link.
please explain the bog more clearly.
cold or hot engine or both.?
is it just tip-in throttle bogging , only then POWER catches, up?
while bogging can you go to WOT and see if it has full power now?
ever get a full 60k mile tune up with new spark parts. and filters.
is engine misfiring.
is engine idle too low rpm or too high with a hot engine?
is fuel old.
did car sit for long time ? unused?

"not getting gas" can be 2 things, bogging or misfiring
they are night and day different, one is like pulling a dead weight
the misfire is violent engine shaking,
see?
and 2 different diagnostic paths due to that ...

if wot is ok, then that implies fuel pressure is good. and filter.
see?

WOT = WIDE OPEN THROTTLE.
i drove a 99 XJ for 300k miles. and know it well..

free fsm
click fuel system here 96-2001 xj
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

see that page? page 14 in PDF
if you changed the pump, you had it in your hand.
unknowing
its on top of the fuel tank pump RACK.

if engine is tuned up,?
and power is low at wot,
i check fuel pressure live.(under varying engine loads)
if the pressure is out of spec, i get a new filter and PPR.
if pressures are in spec. dynamically.
i find out why the PCM is under-injecting.
ask how. its not hard.
(bad MAP?, , injector balance tests?)

Jul 16, 2015 | Jeep Cars & Trucks

1 Answer

2002 suzuki gsxr 600 bogs at 7,8 and 9 rpm..then when passed 9 after bogging and sputtering pass those rpm,it runs just fine from 9 to 14 rpm.it just recently started doing this.so from idle to 7 and


I assume you are using premium gas. If not you should. Check the plugs. If they are white the bike is running lean.. Make sure the gap is set correctley for your bikes spark plugs. Also check the jet sizes in the carbureator for your modifications and elevation. If the bike was fine and just needed a tune up i would pull the map off and reinstall the stock one.

Oct 18, 2012 | 2002 Suzuki GSX-R 600

1 Answer

163FML (CG200) bogging at low rev


Hi, Marcus and the usual suspects are:
1. Fuel cap or fuel tank is not venting properly.
2. Fuel filter clogged.
3. Fuel line pinched or kinked.
4. Float needle and seat sticking.
5. Float level too low.
6. Carburetor bowl vent line clogged/blocked/pinched.
7. Idle adjusting screw set too low.
8. Air/fuel mixture screw set too lean.
9. Idle port, transfer ports, slow air jet clogged.
10. Slow fuel jet clogged.
11. Faulty fuel pump.
For more information about your issue and valuable "Free" downloads that you will need please Click on blue links below. Good luck and have a wonderful day.
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Motorcycle Message Board Motorcycle USA
boging and half throttle
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Mar 17, 2017 | Motorcycles

1 Answer

1993 Mazda Protege as im leting the cluch out the car bogs out like its going to die i put the clutch in tell it go's back to normal and this can happen in all the gears at a low RPM it doesn't ...


Possible that the RPM for IDLE is set too low and so it seems to die off when the clutch is depressed. Check for the IDLE RPM to confirm. Also please make sure if the tuning, timing and the fuel settings are correct. If a scheduled maintenace was not done it will bbe good to have a tune up, check fuel pressure and settings along with the timing.

Oct 16, 2011 | 1993 Mazda Protege

1 Answer

If I'm low on coolant will the bike bog down and


She will loose power and possibly shut down if overheated. Check your cyclinder pressure. Make sure head didn't warp.

May 14, 2011 | 2006 kawasaki KX 85

1 Answer

Low-end Bog


tried this on the carb turn the mixture screw in a 1/4 of a turn

Oct 09, 2009 | 2003 Honda CR 125 R

1 Answer

Yz 150f bogs when you give full throttle all at once


ok, assuming you replaced the carb header and stator with aftermarket parts, then I would say you definitely have a jetting issue. that flat spot is coming from your engine starving for fuel. its taking the gas too long to get from the carb to the engine. you would fix this by adjusting the idle mixture on the carb. the first thing I would do is look for the fuel mixture screw on the carb. im not familiar with your specific model. but the screw is usually found facing down on the bottom of the carb, directly in front of the bowl. when you find it, turn it counter clockwise about 1/2 turn at a time until that flat spot fades away. if that doesnt work, then you will need to up the size of the pilot jet inside the carb. maybe 1 or 2 sizes would be enough. if you replaced the carb with a bigger carb, then you may not be able to fix this problem. in my experience, larger carbs will increase power, but usually throttle response, especially low end, suffers considerably. the reason for this is lower intake velocity and vacuum. basically, with a bigger carb it takes a second longer for the fuel to be drawn from the carb and properly atomize with the air. hope this helps.if I overlooked anything let me know! some more info on the engine/modifications and carb/jet sizes would help too. good luck.

Sep 06, 2009 | 2004 Yamaha YZ 250 F

1 Answer

I have a 2006 kx250f engine seems to be running fine but at 1/4 throttle engine seems to be bogging or missing a bit


I would start out with the basics first: clean air filter, new spark plug, fresh fuel. Then move to the intake and exhaust and check for leaks. A loose carb or adapter, a leaky exhaust seal. The exhaust uses a copper ring seal, they have a tendency to wear out or be vulnerable to a header that has been knocked out of alignment. If everything still checks out, try cleaning the carb, and be sure to remove all jets and blow compressed air through all passages. Next I would check for valve clearances, and if your capable, a leak-down test to check for a worn top end or valves. If the problem has seemed to be for most of the bikes life, you may want to try rejetting the bike to fine tune your low-speed circuit.

Jun 18, 2009 | 2002 Yamaha TT-R 250

1 Answer

1987 rm 125 starts and idols fine, bogs out on take off!!!!


Pull the slide out of the throat of the carb then move the clip at the top of the needle down one notch, two if needed. This will richen the low end fuel mix.

Need a "very helpful" rating asap. Thanks!

Jun 15, 2009 | 2003 Suzuki RM 125

2 Answers

John deere chain saw model ev55 (1986)


I don't know where you can get a service manual. You've described the symptoms of a dirty clogged fuel filter down inside the fuel tank at the end of the fuel pickup.

Carl

Nov 02, 2008 | Electrical Supplies

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