20 Most Recent 1985 Yamaha XJ 700 X Maxim - Page 9 Questions & Answers

I had the same issue with mine, just recently purchased the bike, previous owner said it ran but has been in storage a year and a half. I filled the fuel filter and everything and it would **** down the fuel but never even attempted to fire. I came to find out that there are two lines that come off the tank, the one without the fuel filter has a vacuum on it. So what we did was pour a little fuel down that line to prime the engine because it dumps fuel straight between the carb and cylinder. Took about 3-4 attempts but it fired and ran, just had to set the idle from there. Hope that helps you.

I wonder what the fuel problem was. It kind of sounds like the idle jet, and/or low speed jet needs to be cleaned. Also while your in there, i would clean all the jets, and check the float bowl height.

Great bike I use to have a 81 XJ650J, hell of a bike, i miss it.

take the seat of and you will find two bolts at the bottom of the tank and slide the tank back the un do the hoses

You will have to remove the carbs, and dismantle the float chamber, carefully removing the floats and the float valve from its seating, cleaning to ensure it doesnot stick and also closes off the fuel

Check that your Engine kill switch is in the Run position.

Bike must be in neutral (with neutral light showing) to crank starter, if you try starting in gear the clutch switch must be activated (lever in) and the sidestand must be up.

It should be under the seat.

Hello, from your description, it sounds like some of the jets of your carburetors are in the wrong places. Your bike has four carburetors, and each one of them has a main fuel jet and an idle fuel jet inside the bowl. The main jet goes in the very middle of the bowl and is the one that screws into the needle jet. This main jet has a relatively large hole through the middle. The pilot jet goes off to the side of, and screws right into the metal of the carburetor body. This jet has a very small hole through the middle -- so small that it may be hard to see through it.

These two jets look similar at a glance, and they have identical threads which makes it easy to get them in the wrong place. You mention that your carburetors have been cleaned, so there is a good chance that whoever cleaned them accidentally switched these jets in some or all of your carburetors.

If these jets are switched you will notice the following symptoms:

1. Your bike will start very easily with little or no choke even when it has not been run for a while.
2. Your spark plug electrodes will be very dark black after even a little running.
3. It will feel like you have little power from the middle of the throttle all the way to wide open throttle (WOT).
4. If you run like this for a while you will start to get backfiring, and the bike will start to run on three and then two cylinders, and perhaps eventually not at all.

But don't worry, fixing this problem is easy. It will be especially easy if you are the one who switched the jets in the first place. You just have to take your carburetor rack off of the bike, and remove the four bowls from the bottom. Look at the main and pilot jets in each of the four carburetors. The main jet should have a biiger hole and will have a tiny stamped number that should be around 120 or 130 on the top. The idle jet should have a small hole and a tiny stamped number around 15 or 20 in the top. Be sure that the jets are in the right places, and put your carburetors back together. It is also a good idea to get new spark plugs after you correct the problems, or thoroughly clean your old ones as carbon buildup on the spark plugs may cause a weak spark.

In the attached picture the main jet is toward the bottom, and the idle jet is on the top.


Good Luck,
-Josh

There are many reasons that an engine can run too rich, and the place to start is to be sure that running rich really is your problem. Running rich means that the fuel:air ration in your cylinders is too high. That means that there is too much gas and not enough air getting to the cylinder. The easiest way to verify that your bike is running rich is to run the bike for a little while, then pull out the spark plugs and take a look. If they are covered with dark black carbon build up, then your bike is in fact running rich. Be sure to check all four plugs to see if all your cylinders are rich or just a few of them.

If you are running rich, then you almost certainly have something improperly adjusted in your carburetors. If you are not the kind of person who likes to work with small parts, and keep your workbench organized, then working with carbs is probably not for you. But if you do like to tear things apart and get to the heart of them, then press on and we'll have your bike running right in no time.

The most likely cause of running rich is that your bowls are flooded. the bowl is the bottom part of the carb where the gas sits, and your bike has four of them. each one has a flat-head screw on the bottom side, and a nearby nipple where you can connect a piece of clear hose. Connect a clear plastic hose to the nipple, and then use a flat screw driver to loosen (but not remove) that screw. When you loosen the screw, gas will flow from the bowl into the hose. Hold the hose up to the side, and the gas level should be about even with the seam where your bowl connects to the body of the carb. If the gas level is any higher than that, then your bowls are flooded. That means that your float needle seats are not sealing correctly inside the carbs. This can be caused by having pieces of debris or rust clogging the float needle seat, or by having old worn out float needles. you can remove the carbs from the bike and check each float needle individually. The rubber tips should be cone-shaped, and come to a nice point. The brass seats should be clean and free of debris. Clean everything out with carburetor cleaner from your local napa or auto zone, and put it back together. Be sure not to get carb cleaner on your float needles or other rubber parts though as it will dissolve the float needles. If your float needles are worn, then they will need to be replaced. If the inside of the carbs are just dirty or gummy, then clean them out until they are nice and clean.

If your bowls were not flooded, then you may have a problem with the fuel jets. A lot of people take carburetors apart to clean them, and get the little brass jets in the wrong place when they put it back together. Each jet has a tiny number inscribed on its top surface. The bottom side of the carburetor (inside the bowl) has two jets that look similar and have identical threads, but the holes that go through them are not identical. The main jet is the one that goes right in the middle of the carb and screws into the brass needle jet. It's size is around 120. The pilot jet goes off to the side and its size is around 35. The threads on these jets are identical, but if you get them in the wrong place, then your bike will always run rich -- especially at idle. Check all four carbs to be sure that the jets are correct. Another good indication that you have the jets switched is if you can easily start the bike without choke even if it is dead cold.

If both the jets and the fuels levels look good, then you may have more serious problems. But those two are the most likely cause. Those are things that are easily overlooked by first-time mechanics, and they are pretty easy to fix if you have patience and are willing to deal with the small parts that go inside of carburetors.

Good Luck,
-Josh

70 % problem is bad fuel and 20 % bad fuel mixiture 10 % spark problems.

The fuse should only connect to the pos side of the battery

Sounds like the choke is on to me. Check it and see

cam chain?

You should only use a JASO MA certified motorcycle oil. 10w-40 for cold climate and 20w-50 for warmer climate. Do not use any oil that is Energy Conserving it will shorten the life of your wet clutch and transmission gears. Synthetic oils will help you bike run cooler and shift easier especially in hot weather.

clean the crabs good check intake boot between carbs and cylinder

If I understand "the petcock was in prime position and it eventually quit dripping."
Prime = on
Sound like the needle rubber was hard and after a while they soften up enough to cut off the fuel.
Keep an eye on it and ride safe.
Ken

Take out the pilot air screw[s] from the carbs and remove the pilot jets. Check for dirt and make sure the hole in the jet is clear. Check the pilot air screw for dirt wipe clean carefully as the inboard tapered section is easily damaged.
Check the float bowls are clean remove main jets and check they are clear of any dirt/debris etc.
Make sure when you replace the pilot air screws you screw them in carefully until they just stop. Do not over tighten in any way. (Be very gentle please). Then turn them out the correct number of turns as stated in you manual.
The pilot jets control starting and throttle opening up to about halfway.

try using a thicker oil 1st--ask a cycle shop owner for their brand--may need to do a top end if that doesnt work--purchase a clymer manual for rebuild details

Most motorcycles have a side stand safety switch. If you forget to put your side stand up and put the motorcycle in gear it is designed to turn the engine off . If you put the side stand up before putting the bike in gear , it will remain running. This is so you do not drive down the road with your side stand down, take a left turn, and crash your motorcycle.

Are you starting with aa charged battery? Are you starting with an electric starter or does this bike have a kick starter? Did you measure if you have any voltage coming out of your generator?

HI, LETS REMEMBER THE STARTER RELAY IS ONLY A MAGNETIC SWITCH, WHICH WHEN THE STARTER SWITCH IS PRESSED IT OPENS THE CIRCUIT AND ALOWS 12V DC TO COMPLETE THE CIRCUIT TO THE STARTER MOTOR, IF YOU BRIDGE THE 2 THICK WIRES AT THE STARTER RELAY WITH THE IGNITION SWITCHED ON, 1 COMES FROM THE BATERY, AND THE OTHER GOES TO THE STARTER MOTOR, AND YOU HAVE SUFICIANT POWER IN YOUR BATTERY THE ENGINE WILL TURN OVER AND START, THUS ELIMINATING THE RELAY, IF THE STARTER DOES NOT TURN OVER THE ENGINE WHEN YOU DO THIS IT IS LIKELY THE STARTER MOTOR ITSELF IS NOT WORKING CORRECTLY, YOU COULD ALWAYS REMOVE THE WIRE FROM THE RELAY AND PUT IT MOMENTARILY DIRECT TO THE POS SIDE OF THE BATTERY, INSTEAD OF BRIDGING AT THE RELAY, REMEMBER THAT IF THE BIKE RUNS WHEN YOU JUMP START IT, THEN THE PROBLEM IS WITH THE STARTING SIDE , AND NOT THE IGNITION SIDE AS THE IGNITOR IS CONECTED TO THE IGNITION SIDE REPLACING THIS WOULD BE A WASTE OF FUNDS. THESE MACHINES ALSO HAD PROBLEMS EARLY ON WITH STARTER MOTORS & THE STARTER CLUTCH, WHICH IS A ONE WAY CLUTCH LOCATED IN THE LH ENGINE COVER ALONG WITH THE AC GENERATOR