81 xj650 runs 2-8 seconds

I ran the bike last spring but not scene. I got it out and add new gas and i got it to start but not run well it was only hot on 2 of the 4 exhaust pipes so I cleaned the carbs and removed all gas and put fresh in and tried to restart it and It only will stay running if i spray starting fluid into the air box. the petcock only lets fuel through on the pri setting and not the ON setting which i don't know if that's what its supposed to do or not. guess My opinion is that its not getting enough gas but not sure, scene it only runs if i add starting fluid.
thoughts, places to start.

 

petcock sounds right. its a vacuum so it runs off of the vacuum from the carbs if it's anything like mine. as for the running issue it could be maybe a coil depending on what cylinders it is? should be 2 coils. one runs 2 cyl and the other obviously the other 2. see if the 2 cold pipes are on the same coil?

 

new fuel filter?
i bought one I thought was really pretty looking
but alas was not letting enough fuel flow to the carbs
it too would run for seconds at a time

 

After I cleaned the carbs and it is still not running on all four but still running longer. Where is the fuel filter? it that the thing off the petcock that goes into the fuel tank? I havet done anythig sense last fall but new oil filter oil air filter and tires.

 

fuel filter would be between the petcock and carbs well an inline would be anyways i know mine has one on the inside but i have an inline in it anyways. the only other thing i can think of man is if you DO have spark on all 4 maybe you need to sync your carbs and set your mixture screw to factory setting. having way unsynced carbs would make it run rough and same with the mixture screw being too far in

FYI you should let us know what kinda bike you got. some of these guys may know what to go right into with what type of bike you have

 

If it runs on starting fluid but not otherwise, that means there is a fuel delivery problem or a vacuum leak. See if the bike runs with the petcock on prime (pri). If it doesn't, turn the lever back to on, then take the fuel line off of the petcock and switch the selector back to prime. If gas comes out, that narrows it down to either a really bad vacuum leak, bad fuel filter (as mentioned above), or incorrectly assembled carbs... Start there and report back

EDIT: come to think, fouled plugs may cause this symptom. Sometimes they still spark, but not good enough... It won't hurt to get a new set if plugs to rule out the possibility of fouled plugs. Or you could take a torch to them in a pinch.

 

If your bike is all original, it won't have an in-line fuel filter. That's an "up-grade" we add to our bikes.
Yamaha's idea of a fuel filter was a screen on the petcock and screens on the needle valve seats. Not one of their better ideas.

 

Vacuum leak . . .
Check out this cool Inner Tube Trick.

Fact: your bike is 33 years old, plan on getting very intimate with it.

What part of Wisconsin you in?
Quite a few cheeseheads gathered around the bubbler here.

 

The petcock is vacuum operated; check the integrity of the vacuum line (the small line from the back of the petcock to the spigot on the #3 intake manifold.)

However, you've got a bit more to do than that:

Pull the carbs back off, properly service them, accurately wet set the float levels and do a nice careful bench sync.

Check your valve clearances and adjust as needed to bring them into spec.

Return the carbs to the bike for a running vacuum sync.

But for starters, get ahold of a service manual; you're going to need it.