20 Most Recent 1981 Yamaha XJ 650 - Page 5 Questions & Answers

Is it poss to remove the float bowl while the carbs are fitted to the bike? I am fairly sure back in the eightys the float was addjustable, to controll the fuel level by bending slightly the metal tab on the float, when the bowl is removed check the level of fuel in the bowl and compare it to that in the others, the aim is to make the fuel flow stop at the correct level in the carb(by bending the float tab) while the bowl is off turn on the fuel push the float all the way up check if the fuel flow stops, also check the condition of the sealing washer around the float needle seating.

The flasher is located underneath the front of the fuel tank fust behind the horn. I hope this helps. I am looking for a wiring diagram for the 1981 Yamaha XJ 650.

You can use a bicycle pomp, push the pomp till its end, dip it in the oil and **** it up.

You need a equaliser (i think thats what it is called). I had the same problem with a custom bike, the voltage is designed for a certain volt and if you change it than it will not work properly, any after market motorbike shop should have one, they are fairly straight forward to hook up, directions should be in pack.

Hi,

Look in front of the engine between the exhaust header pipes. There is a finned aluminum housing held by a bolt and inside is the paper filter element.

Even though I am unfamiliar with your bike I will give this a try on the condition that You give me a "Helpful" rating or better. Like you, I am unable to comprehend pigeon English.

A spark plug can go bad at any time. Get a new plug. Put the wire on the plug then ground the metal side of the plug against the cylinder head as you press the starter button. Look for the spark. If no spark, check the side stand kill switch. It kills the engine so that you don’t start out with the side stand down. If broken or out of adjustment, it would kill the spark. Check for a broken wire at the side stand switch and coupler. Try moving the kill switch by hand. If that doesn’t work then wire a jumper around the switch to bypass it. Check the fuses. How good is the battery? Is the handlebar kill switch on? Check the operation of the ignition switch and all kill switches with a volt ohmmeter.

A direct crossover is not likely. The 650 will have a bigger bore. The part numbers are different as well. I believe I found what you need at the following website www.babbittsonline.com be sure to get new gaskets also. Please rate my answer. Thanks.

Air getting in BEFORE the carb is unfiltered and can harm the engine. Air getting in from BETWEEN the carb and the head is also unfiltered but more importantly leans the fuel/air mixture causing the engine to run hot and sometimes causes the idle to climb by itself. Compression is getting past the piston rings, (blowby), and into the gearbox. The fuel/air mix getting into the gearbox, mixes with the gearbox oil diluting it, and some of the oil follows the pressure through the crankcase vent hose and into the airbox. Chances are that raw gas went from the tank and into the gearbox over the winter. This raises the oil level in the case and promotes the oil going into the gearbox. Just do an oil change and be sure to turn off the fuel valve at the tank when not riding. Please rate my answer.

When the carburetors over flow enough to fill the exhaust, It is possible that the gas also went into the cylinder and flowed past the rings and into the crankcase. With the engine overly full of gas and oil you could easily pop a seal or blow out a gasket. Check your oil level. If it is too full , change the oil, it will not lubricate properly with all the gas in it. Check that your shaft seal has not popped out. Check the air filter, the breather may have blown oil and gas all over it when you started the bike. Empty your pollution tubes behind the motor( they will drain the air box). Get in the habit of turning your fuel petcock off when not riding. This gas flooding happens randomly in certain models but can happen to any one.

Hi,

It has to be ' clockwise '.

Thanks and Regards
taran_2005

the atv must be in park or neutal, turn the key on and make sur the kill switch is in the run position turn the choke on located on the left handle bar under the head light switch, hit the start button and its should fire

First verify the oil level......on the sides of the window are an upper and lower mark. I believe on your model the oil fill cap is very close to where the window is....remove cap and use a clean tape measure as a dipstick. Lock the tape at say 5 inches, rest the tape body on the fill hole, pull out and have the part of the tape measure body rest on the fill hole and the extended tape on the outside so you can compare the actual level dipped to the marks for min and max on the sight glass. If its high drain it down to correct level.

It will have CV carbs, called constant velocity.
The cable and linkages open the butterflies on the intake side, the slides wont move until the air flow through the oval looking hole at the top causes the diaphrams to lift the slides.
you should be able to lift the slides individually with your finger , and they will drop down again.
I think the chokes lift a plunger in each carb, and is called an enrichening device, as it opens another jet to richen it for cold starts,the choke does not work the same way as a car ar a standard slide carb.

Probably its the bushing it the speedometer. Look where the cable spins in the speedometer...and where the cable sheath screws on.
You need to get some light grease sparingly into the space between the rotating head and the stationary part...I use white grease on my fingertip to push some in.. If the bushing is dry....it slows down the rotating head and the cable starts twisitng till it snaps. Normally a dry bushing starts making noise though.

When you say you replaced the cable....you meant the cable and the outer sheath correct....if the cable only was replaced there may be an issue in the sheath that is snagging the cable.

You may be able to purchase the jets separately from Sudco.com. Your local dealer may be able to order from this company directly or an online supplier may be able to get them for you also. Some times these companies require a minimum order.

here you go...1-2-4-3
see attached...
http://www.motorbikespecs.net/index.dyn?flag=2&model_id=2147990&make=Yamaha

You would have to buy a service manual for that bike it will tell you all the carb settings in it.

The VIN number should be 17 characters and found on the frame....should start with JYA

Now count off from the left to the 10th character,,,,,,,
if its an A its a 1980 model, B is an 1981, C is a 1983.

the 4H7 in the VIN means its an XJ650H model made in 1980 & 1981, Look up XJ650 on the net for more info on your bike.

Hi,

The timing in this engine is not adjustable.

http://www.repairmanualclub.com/motomanuals/index.php