Question about 1980 Yamaha XS 400

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How do i begin adjusting the carbs? - 1980 Yamaha XS 400

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1st-clean air filter and oil,fresh plugs,good fuel,valves adjusted correctly,check for tears or cracks in intake boots,fire in all cylininders;minimum compression & w/in10% of each other in all cylinders, and no exhaust gasket leaks. once these components are w/in specs. and operable the carburators can be adjusted, as long as they are internally clean and operating as designed.1st- set high idle, then set idle rpm, now synchronize vacuum on carburator set,now readjust idle rpm.

Posted on Feb 19, 2009

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What is the hight of the float in the carb


if the exact height is not known , a good rule of thumb , is to tilt the carb on its side (with float bowl off) and watch the float to see when its just begins to push on the float valve .... at that point the floats should be level with the sealing face that the bowl bolts up too ....if not , bend the little metal tang till it sits level ..... hope this helps

Jun 02, 2014 | 2002 Honda XR 200

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Hey I have a 1974 Honda CB200 which runs with two carbs but i am having difficulty in tuning them right . fuel efficiency is poor . So i want to ask you if i can replace those two carbs with one carb like...


The power would not be changed. If the distance between the intake ports is the same, you should be able to do the swap. That air filter will need to be changed also. Before you spend money, how about spending a little bit of time instead? Remove the carbs then remove the float bowl at the bottom of one of the carbs. Only work on one carb at a time. Remove the air and the throttle screws. Now use spray carb cleaner to clean the inside of the carb. Spray into every fitting and drill hole you can find. Spray from both ends of a fitting or hole if possible. Put the float bowl back in place and then put the air and throttle screws back in. Turn them inward until they LIGHTLY seat. Noe turn each of them outward one and one half turns. Now clean the other carb the same way...
Mount the carbs back on the bike. First, synchronize the two carbs so that the slide in the center of both carbs begins to raise at the exact same moment when the throttle is twisted. The motor is turned off for this adjustment. Use a mirror to see the slides when the throttle is gently turned. Adjust the cable fitting on top of the carb that is latest to begin to lift, turn the fitting outward. Start the bike and then adjust the throttle screws equally to set the idle speed. It would be a good idea to balance the carbs also. I can tell you how in a reply. Answers that are too long get cut off by Fixya.



Aug 15, 2011 | 1974 Honda CB 200

1 Answer

My 1983 yamaha virago 500 is having trouble around 3 to 4 thousand rpm and now is having trouble starting and staying started


Sounds like your carb is dirty in all areas. Remove the carb and completely disassemble it. Blow carb cleaner and compressed air through every opening and make sure each opening comes out somewhere when you spray through. Clean the float needle seat with a q-tip and carb cleaner. Spray through each of the jets and be sure they are absolutley clear. Make sure you get the emulsion tube out and clean. it is what the main jet screws into and will have holes down the sides.Screw the mixture screw in and count the turns. remove it and any spring or o-ring and spray through it also and make sure the spray goes all the way through. Replace the mixture screw and set it in the same adjustment as you started. Reassemble and install the carb. If the carb was adjusted properly in the beginning, you should put it back on and your bike run much better.


*Help me out. Rate me!

Apr 27, 2010 | Yamaha XS 500 Motorcycles

2 Answers

Can you put racing fuel mixed with 93 octain to help the hesitation on my magna


That will likely not fix the problem. You have an adjustment problem that is causing the hesitation to begin with, treating a symptom will not fix the problem. I suggest that you address the hesitation, (fix it), then you won't have to resort to mixing up fuel to treat a symptom. I would look at fuel delivery and throughly clean the system, if you still have a problem, have the carb adjusted. Should fix the problem. Good Luck! Hope this is helpful.

Oct 27, 2009 | Honda VF 750 C Magna Motorcycles

1 Answer

Left bank won't fire at low speed. It is a 2004 790 bonneville triumph.


Chances are the carb slides are out of synchronization. Remove the air filters and look inside the carbs ( with a mirror if need be ). With engine off, crack the throttle and see which slide begins to raise first. Adjust the other carburetors' cable to make the slow carb raise to match the timing of the other carb.
Put in some new spark plus as well.

Aug 19, 2009 | 2004 Triumph Triumph Bonneville

1 Answer

Honda cr 125 1997 wont idle


Your carberautor is either gummed up or needs to be adjusted. Begin by going to an auto zone or similar store and gatting a can of carb. cleaner that gets added to your gas. Be sure to follow the instructions on how much you add per gallon. let that run through your bike for a while and see where you are. If cleaning the carb. doesn't hellp, then the carb. will have to be adjusted.

May 27, 2009 | 2002 Honda CR 125 R

1 Answer

Bike won't stay running


Drain the carburetors. There should be a screw on the lower side of each CARB float bowl. Remove the screw then replace it after the fuel drains. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, (not all bikes have a water trap bowl). Install new stock NGK spark plugs.

Remove the CARBS from the bike.
FOR EACH CARB > 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 idle screw and the air screw 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. Install an in-line fuel filter. Let the float bowl fill then start the engine.

BALANCE THE CARBS
Turn the throttle screw on the LEFT CARB one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left CARB to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT CARB one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right CARB to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both CARBS. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each CARB such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other CARB.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other CARB so that the slide on that CARB just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both CARBS begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

Turn the idle screw on each CARB EXACTLY ONE HALF turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just balanced and synchronized your CARBS This should fix the problem. One last and VERY IMPORTANT thing, Have a fire extinguisher handy and ready for use any time you work on or with he CARBS.

Please rate this solution. Thanks throttlejock!



Apr 22, 2009 | Suzuki GS 500 F Motorcycles

1 Answer

Timing Adjustment issues!


If the bike runs then Top Dead Center (TDC) is not an issue. But to check piston stroke position, Remove the valve cap cover on the intake of the front cylinder. Remove both the spark plugs. Rotate the crank shaft untill the rocker arm starts to move. The piston is now starting down on the intake stroke. Rotate the crank further and the rocker arm moves in the opposite direction. The piston is now going upward on the compression stroke. Look at the marks on the flywheel. Rotate the crank untill the TDC mark lines up with the timing index mark. The front piston is now at TDC.

If your model has carbs then the backfire fix requires you to syncronize and balance the carbs.
SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

BALANCE THE CARBS
Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just balanced and synchronized your carbs.

Please rate this solution. Thanks sgtswampdonk!

Apr 02, 2009 | 1999 kawasaki VN 800 Vulcan Classic

1 Answer

Honda 1300c backfire through carb at wide open throttle. I have open up the exhust and rejetted the carb . the bike will run fine up to mid throttle or 65 mph but if you accellerate hard or go to wide open...


Try balancing ans syncronising the carbs.
BALANCE THE CARBS
Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed.

SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

Please rate this solution. Thanks!

Mar 30, 2009 | 2004 Honda VTX 1300

2 Answers

Raptor 660 idles but no throtle response


Turn off the gas and remove the water trap bowl at the bottom of the petcock, (gas valve). Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ). Get a set of the stock NGK spark plugs your bike came with. Check for spark on each cylinder before installing the plugs.

Now go to the idle and air screws on the outside of each of the carbs. IMPORTANT > > GENTLY turn both screws all the way in until they LIGHTLY seat. Now turn the screws EXACTLY one and one half turns outward.

SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

BALANCE THE CARBS
Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just synchronized and balanced your carbs.

PLEASE RATE THIS SOLUTION. Thanks!

Mar 28, 2009 | 2001 Yamaha XTZ 660

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