Rebuilt 2003 Vulcan 750 engine - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 5 (permalink) Old 03-03-2014, 10:27 PM Thread Starter
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Rebuilt 2003 Vulcan 750 engine

We rebuilt the engine due to a coolant leak in the rear head.
New gaskets and cleaned carb.
We put everything back together and double checked the timing.
Now when starting, it will fire up and run cold without adding choke.
When it gets warm, it backfires.
When turned off, it doesn't start again until cold.
We think due to gas flooding the carb.
Help? Or it is in to the shop to spend more money.
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post #2 of 5 (permalink) Old 03-03-2014, 10:45 PM
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Was there any starting issues before the rebuild? The rectifier/regulator has been known to overheat, making hot starts difficult.


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post #3 of 5 (permalink) Old 03-03-2014, 11:04 PM
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Did ya clean the carbs when the motor was rebuilt?

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post #4 of 5 (permalink) Old 03-04-2014, 09:01 AM
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Just a shot in the dark here but when you rebuilt the carbs if you got the floats off, or not seating properly then you could flood the bowls after shutting off. Given time to "cool down". During this "cool down period" the excess gas could drain out or evaporate out of the bowls.

A possible test.
petcock on, start and run until warm. while still running turn the petcock off and allow to run out of fuel killing the engine.

Now reopen the petcock. Realize that it will take a bit of cranking time to allow the vacum diaphragm in the petcock to allow enough fuel to refill the bowls. My bike can take eight to ten 3 second starter sessions to get enough fuel past the vacum diaphragm in the petcock to refill the bowls.

If engine restarts (may run rough the 1st 30 seconds as the bowls finish refilling) while still warm (allowing for the effort of refilling the bowls) then I would suspect the floats or their seats.

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Last edited by Spencer1; 03-04-2014 at 01:17 PM.
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post #5 of 5 (permalink) Old 03-04-2014, 10:51 AM
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whats the gap between the ingnition pickups and the rotor?

thats real similar to the hot start symptoms, with can be cured by reducing the gap of the coils
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