Hi, Mike engine "BOG" is mainly caused by a rich air and lean fuel condition but it can also be caused by a lean air and rich fuel condition this situation rarely occurs and is only caused by the misinformed weekend warrior that owns a toolbox.
The more you open your throttle the more vacuum you are creating in your carburetor venturi and your intake manifold. When you are operating at higher RPM any unmetered air that leaks into your system can become more obvious.
Unmetered air is air that is getting into your system after the fuel has been delivered. If you have unmetered air getting into your system between the butterfly/slide of the carburetor and the cylinder head this will create a lean condition.
All of the rubber components of the fuel system like vacuum hoses and intake manifold that you mount the carburetor to are made of rubber. If none of these components have been changed out they are more than likely highly degraded and probably cracked in places to allow unwanted-unmetered-contaminated air into the combustion chamber. Check all of your vacuum lines and vacuum plugs for carburetor synchronization. The vacuum plugs are in the head just after the rubber intake manifolds. The petcock has a vacuum line as well as part of the emission system.
1. Check the intake manifold for cracks.
2. Ensure the bands used to tighten the manifolds down on the intake are secure and have not bound up the manifold.
3. Make sure air box fittings are not warped and fit completely over the carburetor.
Your airbox is metering air and is the first step in a process of consuming air and fuel. The system requires the resistance of the air filter in order to get the proper vacuum to "SUCK" the fuel out of the float bowl and create the proper venturi effect.
Improper mounting and sealing of the airbox will create a small lean effect. This might seem like no big deal but you are inviting dust and debris in your engine that is doing slow damage by not having proper fitment. Fix it so you know it's not contributing to your issue. Pick the low hanging fruit first.
Do not go and start adjusting anything at this point. It ran fine before. There is something wrong with the assembly or a component. Do not adjust your floats. Get it back to where it was. The moment you start tweaking everything is the moment you lose OEM settings which are a must have for fine tuning and maximum performance.
Fine tuning your carburetor and multi carb syncing come at the very end following the proper procedure established by the Carburetor Gods.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. 2001 XR250R Off Idle Bog 1986 Honda XR250 Bogging Issues Honda XR250R Service Manual http://www.partsfish.com/page/oem-parts-for-honda Honda XR250R Owner Manual
No, because it may take some time for the oil to heat up and expand. Then, once this happens, the oil can begin to get whipped up by coming in contact with moving engine and transmission parts. Oil foaming can occur and over-run the crankcase ventilation system.
To help eliminate this problem, be sure to use the correct oil as recommended in the Honda owner's manual. Do not overfill the crankcase with oil. Change the oil and filter more frequently - especially after riding through deep water crossings.
If you suspect worn piston rings, check the spark plug for oil contamination and perform a cylinder compression and leak-down check.
you should not use detergent added oils in a small engine. they tend to foam up in high rpm small engines this can adversely affect the lubricating abilities of the oil and cause issues with the wet clutch. use honda gn4
Oil change only...
XR250L XR250R................................. 1.3 liters (1.37 US qt)
XR400R.............................................. 1.7 liters (1.8 US qt)
Oil & filter change...
XR250L XR250R................................. 1.4 liters (1.5 US qt)
XR400R.............................................. 1.8 liters (1.9 US qt)
After engine rebuild...
XR250R, 1986 through 1995 XR250L..... 1.6 liters (1.7 US qt)
1996 and later XR250R........................ 1.7 liters (1.8 US qt)
XR400R.............................................. 2.2 liters (2.3 US qt)
Hi, Jhun before testing any electrical component in the Charging System it is "IMPERATIVE" that you have a fully charged battery of 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage, the battery is faulty and must be replaced. AGM type batteries fall into this scenario more so than lead-acid batteries.
1. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
2. To check the regulator unplug it from the stator. Take a test light and clip it to the negative terminal of the battery and then touch first one pin and then the other on the plug that goes to the regulator. If you get even the slightest amount of light from the test light the regulator is toast.
To do this with a meter: black lead to battery ground, red lead to each pin on the plug, start with the voltage scale higher than 12vdc and move voltage scale down in steps for each pin. Any voltage is a bad regulator.
3. On the other part of the disconnected regulator plug. Set the multimeter for Ohms x1 scale and measure for resistance across the pins of the stator. You should read something around 0.1 to 0.2 ohms for a 32 amp system.
4. Then check for continuity between each pin on the plug and frame/engine ground. The meter needle should not move (infinite resistance)(digitals will show infinite resistance) if the meter needle does move (indicating continuity)(digitals will show some resistance), recheck very carefully. If the meter still shows continuity to ground the stator is shorted (bad).
5. Set the meter to read A/C volts higher than 30 volts (the scale setting for voltage should always be higher than the highest voltage you expect or you may fry the meter). Start the bike, and measure from one pin to the other on the plug (DO NOT cross the multimeter probes! - touch them to each other). You should read roughly 16-20 vac per 1,000 rpm.
6. If the battery was good under load test, if the stator is NOT shorted to ground, and the stator is putting out A/C voltage, then the regulator is bad (most likely even if passed step 2)
For more information about your question and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. How to Fully Troubleshoot Your Motorcycles Charging System MotorcycleMD How to diagnose and repair motorcycle charging problems Honda XLR200R Service Manual https://www.partsfish.com/page/oem-parts-for-honda http://www.hondampe.com.au/repository/owning_a_honda/owners-manuals/off-road.aspx