82 seca xj fuel fouled big time in ten miles

Hey vj enthusiasts...first post here

I have a 1982 seca 750 xj that i have owned for 15 years. A month ago i was riding and i began to dump fuel into the crankcase and blowing black smoke out both exhaust pips. So..i thought, well its time to have some work done ......heheh i have only ever put tires on this thing...it has always ran beautiful. i had the carbs rebuilt/ replaced the carb boots, etc.
NOW...in ten miles it fuel fouls and will eventually quit running altogether.
I took it back, the shop put new plugs in...ran great..for about 10 miles...took it back again....put new plugs in ...the shop is clueless. The compression is at 145 ..on each cylinder ....and the plugs are covered in soot ...its not oil. The shop says the engine is wore out and i just dont think so. Put new plugs in...it runs like brand new ..for 10mi. Anybody have any suggestions i would greatly appreciate it. Nice to meet everyone BTW.

Justin

 

Did you solve this problem?
Did you drain the oil out of the crankcase and refill with fresh oil?
Did you check your air filter and filter box for oil?

Basically when the crankcase gets fuel in it, it's overfull, blows thru the crankcase breather into the filter box, soaks the filter, engine runs very rich, and dies! Let it sit and after 1/2 hour or so it will run again for a bit then die.

 

Yes the oil has been changed and the level is correct. With the initial incident the air cleaner WAS completely full of oil. This is no longer a problem. The oil was cleaned out of the airbox and the air cleaner was of course changed and is still looking good as new. The oil looks great and is about 3/4 the way up the inspection window. The biggest thing i notice is the black smoke it shoots out both exhaust pipes when given a hanfull of throttle...it never used to do this. One guy at that shop said it was the petcock...that the vacuum was not pulling back on the fuel supply....but to me the floats in the carb should handle this...urrrrrrr thanks for ur reply.

Justin

 

Remove the Fuel Supply Hose from the Petcock.
Run the Bike from a Tune-up Tank.

If its Petcock Related ... the source is eliminated and the Bike should run fine.
Use fans to cool the Engine.
Run the Engine at 3,500+ rpm's

If the Engine Fouls during this test, you have a Mixture Issue to overcome.
-Or-

There is another reason the Plugs are becoming Fouled.
Possibly: Valve seals.

Rebuilt Carbs ... done away from the Bike and transported back to where the Bike is ... run the chance of having Float Pins become dislodged from their Tabs on the Float.

The Floats "Vibrate" during transit.
When they begin to vibrate (rattle) the Float Pin's securing wires may become undone as the Pin's and Float's Rising and Falling without Fuel in the Bowls to prevent the "Bouncing" from occurring.

If a Float Pin is "Thrown" you have an overfill situation (for sure)!

 

We will try to run the bike from a remote fuel source.

Thanks