Question about 1983 Honda XL 125 R
1983 Honda xl125R will start but I can't rev it up and it will backfire. I cleaned the carb good and I don't think it is the carb, What do you think?@
Posted by Anonymous on
Hi, Anonymous 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 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 fissures.
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.
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Posted on Jan 02, 2017
SOURCE: honda pal 2 stroke scooter
Are you adding oil to the gas? (32/1 = 4 ounces per gallon)
Do you still have spark? Install a new stock spark plug.
Clean the carb, but follow these steps >
Remove the carburetor from the engine.
Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the two screws on the outside throat of the carb and spray into the screw holes as well.
< < READ CLOSELY > >
Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. Let the bike warm up then set the idle speed. This process should get you back on the road.
Posted on Mar 31, 2009
it sounds to me like the throttle slide has been installed incorrectly,unscrew the throttle housing off the top of the carb(it looks like a cap and the throttle cable goes through it)remove the throttle slide from the housing,down one side of the throttle slide there is a piece cut out that goes the whole length of the slide (lookes like a groove),inside the carb body there is a small brass knob,this groove or cutout goes over the knob and it stops the throotle slide from rotating,once you have installed the slide back in the carb the slide should drop right to the bottom of the housing,you can check this by looking through the rear of the carb and you should be able to see the bottom of the throttle slide,if the slide is installed incorectly the little brass knob stops the throttle slide dropping to the bottom of the housing and will give full throttle,its an easy fix and wont take more than 10mins to repair,hope this helps
Posted on Jul 10, 2009
When I recently ordered parts from Saber Cycle, they included a piece of information that pertained to my motorcycle, which is also a 1983 Honda Goldwing GL1100 Interstate. Here is what it says, I hope this helps:
Air Cut-Off Valve
The air cut-off valve is an extremely important part of the fuel/air intake system that is frequently missed even my competent mechanics, most of whom are not even aware of its existence or how it functions.
Every GL1000 has one, located in the air intake tube, between the air cleaner box and the manifold. Every GL1100 has four, located in the top air intake passage of each carburetor, and every GL1200 has one located in the plenum box below the air cleaner box similar to the GL1000.
These valves are "air blockers", along with the carburetor o-rings, serving to restrict air flow and increase the fuel/air mixture ratio when the carb slides are in the lower RPM range, up to closed so that the machine will start and idle smoothly with virtually no choking and accelerate rapidly, with no stumble or hesitation.
When typical starting requires heavy and prolonged choking to keep the bike running, when stalling and hesitation occurs even while "warmed up" and when backfiring pops while the throttle is shut off while cruising, most people will start fooling with the air screws to try to overcome the problem, only making it worse along with reducing their gas mileage.
Running with dysfunctional air cut-off valves can causes severe engine damage or failure. When the valves are dysfunctional, the engine pulls nearly total air in the low RPM range through the carbs and on to the combustion chamber. The fuel/air ratio is extremely poor with pre-ignition long before the normal 38 to 40 degree firing point, generating an enormous amount of heat, with no power, which is trapped a longer period of time in the cylinder before the exhaust valve opens.
This heat goes mostly up through the cylinder head, gradually incinerating the head gaskets and allowing engine coolant (anti-freeze) to seep into the engine. You can easily spot when you are in trouble by a puff of bluish-white or white smoke on first starting the engine. Don't leave it alone. Change head gaskets immediately or you could take out your bottom end bearings, ruining the engine.
For those of you installing new exhaust systems, you will discolor your headpipes, either blue (lean state) or gold (rich state). You can destain your pipes using "blueaway" or "blue-off" but be careful not to rub the chrome, just dab gently.k These compounds are usually purchased at a Harley dealer or Harley oriented aftermarket shop.
Honda genuine pipes, like many Yamaha pipes, have a double wall for a portion of the headpipe which masks this discoloration-but also masks a bad state of tune. Even if your pipes are original and still in good shape, don't think that you are OK if the bike has any or all of the dysfunctional air cut-off valve running and performance characteristics.
If your 1975 to 1987 Gold Wing is not getting 50-58 miles per gallon (20-23 KM/Liter), you have one of the most obvious signs of trouble. It is likely your air screws have been backed out to try overcome the effects of the poor running, stumbling, starting and stalling and quitting.
Resynchronize all four carbs to the #3 carb vacuum level using mercury carb sticks or vacuum dial gauges. Stay with strict use of the setting levels in either the Honda, Clymer or Haynes manuals. Do not attempt to tune any other way! Guessing will not work and can cause considerable engine damage!!!
Posted on Sep 26, 2009
If the spark at the plug is goog then its a fuel or choke / air problem .Check to see if the plugs are wet after turning over the engine a few times .you may have a sticky choke that not letting enough air in with the fuel mixture .
Posted on Mar 13, 2010
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