VF500 Interceptr starting issues electrical?

So i have been working on this VF500 i got about a month ago for 300 dlls. i took off carbs cleaned them up, previous owner told me it had a bad cdi i did no ask wich one so i got both. i cleaned the tank, got new petcock cause old one was clogged, i got clutch master and slave rebuilt, got new fuse holder box, brand new ignition switch with new keys, brand new brake pads and rotos all the way around, new ignition coils.

Here is the problem i have. everytime i try to start bike, it starts for a second or two and it dies, i checked compression, its good, i changed spark plugs and wires, tested pick up coils and they test good, got another set of cdi boxes so i got 3 o each now and still same thing. earlier today i tried to start and it stayed on for about 30 seconds and just died. funny thing is when i turn the key on the ignition sometimes the fuel pump just comes on, and other times it only comes on when i crank the starter, so i am a bit lost here. any ideas would be greatly apreciated.

 

Probably fuel related. Take out a plug, plug it into the boot, and rest the hex part against the engine (for ground) see if you have spark while cranking (I'll nearly garauntee that you do)

The running for 1 second can easily be done off of fuel vapors. once they are gone, your engine stops. Test your fuel pump, choke system, and look into getting a gravity feed conversion, shouldn't be too hard.
If that fails, then we are looking at a Pilot/choke issue which requires dismantling and cleaning the carbs. If it comes to that, have 4 3" x 1/16 dia rubber o-rings ready to replace the float bowl gaskets

 

Sounds like a no fuel situation. Pull the connector off the fuel pump relay and place a jumper wire between the black and white terminals, turn on the ignition switch, the fuel pump should run. After a few seconds, turn the ignition off and check for fuel in the float bowls by opening the drain screws.

 

i got a brand new fuel pump so there is fuel i will check the choke, i took out the carbs again checked all the jets, cleaned them again they are shiny clean and air goes through easily, i rechecked the float height number four was a bit off so i readjusted to 6.5mm i got a new needle jet diaphram fro number one cylinder as it was torn. the only thing i got left is to take the choke apart on all carbs. My got what a pain to take off and put back in there. this is my 5th time taking those things off. we'll see how it goes. thanks guys

 

Creaky quite correctly suggested a fuel pump relay bypass for testing purposes. Even a good pump won't operate properly if it's relay is unreliable.

For the choke circuit to operate right the long brass non-removable tubes must be probed with a .010-.012" stiff steel wire to a depth of about 30mm. If wire won't go in the best technique requires a pecking action which can take up to about 10 minutes. Holes are not open until you can blow lung air through after slipping a plastic hose over the tube. Clogs are very common and start just at the level where fuel sits in the float bowls.:tongue:

 

awesome tanks for the advice, i actually took the whole thing apart, it was tricky i did not see anything wrong but i will try the thin wire in the brass tube. its the only thing i have not tried. thanks for the advice.