choke problem???

82 xj650....... Bike will crank but not run unless i cover all 4 carbs with my hand. i just replaced the spark plugs, wires and cleaned the fuel bowls. no matter what position the choke is in the bike wont start, as soon as i cover the carbs, it starts and idles a little rough... dies shortly thereafter. any suggestions would be appreciated..... also, the "piston sliders"??? they function off of the engine vaccum???

 

Does this mean the carbs are not connected to the air box?
The slides do operate by vacuum, take off the hats & check the diaphams for holes & that the slides move freely.

 

yea the airbox was not attached to the bike when i got it so i was gonna get the individual pod filters.. now i noticed there was a crankcase breather hose? going to where the airbox should be, would it affect the ignition without it being in the airbox?..... checked diaphragms...no holes... the sliders move freely up and down when i push on them, theres no resistance or binding of any sort.

 

If you wish to enjoy this Bike and ride it for several seasons, then I would earnestly recommend that you acquire a Stock Airbox with Filter and Cover, a set of Connecting Rubber Hoses Stacks and the Clamps and Hardware needed to restore the Bike back to its Original condition.

As you have already learned by needing to restrict the Air Flow into the Carbs with your hands to achieve a Air~Fuel Ratio capable of being fired by the Engine; you problem is entirely too much Air entering the Intake.

Other will offer guidance on how you can experiment with "RE-Jetting" the Carbs. You may find an arrangement of different FUEL Jets will make the Engine run in a manner that suits you. Or, you may find that the situation can only be resolved with a level of Fine Tuning that does not deliver the measure of Tuning that meets with your complete satisfaction.

 

To give you a bit more by way of explanation:

These bikes use CV (Constant-Velocity) carbs, which have indirectly (vacuum) controlled slides.

A CV carb does not do well with an infinite amount of incoming air, such as with the carbs being completely open (or even with "pod" filters.) The bikes are much easier to tune and maintain if you can restore the stock intake plumbing. If not, you enter into "tuning for pods" for which there is no set formula or short and easy answer. You can put a "mini-pod" on the breather if you don't go back to the airbox set-up.

The "choke" is not, it's only the name. It's an enrichening circuit that ACTS like a choke by adding additional fuel.

 

ok thanks guys, im gonna see what i can do with it.

 

ok so i just put in the stock airbox and boots. the bike is now 100% stock.
the bike started for maybe 20 seconds before dying. and now just cranks and cranks, every now and then it will sound like its gonna start but rarely does.. also, should the headlights and guage lights be on when i turn the key to on?? because they seem to only come on when the bike almost starts. if i turn the key back off and thn on again the lights dont work... im at a loss here. any help would be much appreciated

 

Stop cranking it. If it don't Start ... try some Starting Fluid.
If is Starts for a moment on the Starting Fluid and quits ... it's a FUEL Supply Issue.

Make sure the Carbs are getting Fuel from the Tank.
Use the PRI Setting to fill the Fuel Bowls.
See if it runs or tried to start on PRI.
If it does fire-up on PRI ... the Petcock needs testing.

Make sure that the Vacuum Line to the Petcock is good.
See if the Bike Runs with the Safety Relay disconnected and the Bike in NEUTRAL.

 

some (all?) of these bikes use "resistance" plug caps. when you
replaced the wires did you also repalce the caps?
you also mention cleaning the float bowls. if you did'nt clean
the rest of the carbs completley, then you need to go back to work.

1,check your plug wires for the right caps and route to the right
cylinders.

2,thoroughly clean carbs inside and out, bench synq, meter synq.

3,you may as well check the valve clearences.you won't get
a good synq if they are out.

good luck.

 

what about the lights???? is that an electrical problem, or is that how they function?

 

vacuum line is hooked up.. wont start with the the petcock in any position... where is the safety relay????

 

some models,the light stays on when the key is turned on.

some like mine the light comes on after the bike is started.

sometimes, if you can't get fuel flow on prime, you need to allow
some air to escape that may be in the line.

with the petock on prime, carefully diconnect the fuel line just a little.
if you have a in line filter do it there. allow a little flow (just enough
that you know fuel is there) then plug back up. this is the same concept
as the brake lines...air in...no brakes.

can't help with the relay. diff bike. don't wont to be wrong.

 

Try shooting some carb cleaner in the airbox like rickomatic said. The bike should start and run with some throttle work. If it does start that way. It means you HAVE to clean the carbs. Their are holes in the float bowls that I almost guarantee are clogged. They provide fuel to the fuel enrichment circuit."choke" Make sure carb cleaner can shoot through the holes and about 5 feet out the other side.(And not in your eye You have to have those clean in order for the bike to start.

 

ok so the bike will start if i spray carb cleaner in the airbox, but dies immediately after it burns off, i took the carbs apart and cleaned everything, polished all the brass parts and checked the sliders. the jets were clogged but are fine now and it still wont run.. i took my gas tank to be cleaned so as to not clog the carbs again, so i have a funnel setup to the fuel line hanging above the bike. whats weird is that everyday, when i first try to start the bike it will run almost immediately and stay on for about 30 seconds. and then after it dies it wont start again for the rest of the day unless i let it sit for like an hour or so, and the the same thing happens..... whats goin on with this??

 

when my '81 started acting like that right after I got it the problem turned out to be the fusebox, believe it or not. "IGN" had cracked clips.

 

Are your float heights set correctly? Floats in upside down?

 

When you say 100% stock does that include the original glass fuse box? If you still have the glass fuse setup that needs replacing.
It is fairly cheap to replace. I bought box fuse with connecting wires and it works fine. Did you clean out the fuel enrichment circuit holes in the float bowls? If they are clogged the bike will not start cold. It is imperitive that they are clean and free flowing.

 

Check to see if the Battery is able to provide the AMPS you need for running the Bike.
If there's a Charging System problem, ... the Battery will act as the sole Power Supply until if falls below the point where the Bike don't run.

If you have a OEM Fuse Box. Test the IGN Integrity by placing spring-loaded clothes pins on the Fuse Holders to make sure the MAIN Fuse isn't loose and opening the circuit.

Right after it Quits on you, ... take a spare Spark Plug and see if there is Spark or not.
Just Pull the #4 Cap and insert a Test Plug and short it to the Block.

 

i replaced all the clips with weatherproof sealed inline fuses because they were all broken when i got the bike. i dont think thats the problem. but i will double check it, thanks

 

rick i missed your post, i will check the battery and spark in the morning. Thanks for the advice everyone