carb keeps flooding

[jonasbriggs]

any other ideas? Ill rebuild it once more and try to see maybe I've done something wrong but i gotta make my baby run. 

[gsx600racer]

Dec 19, 2017 12:19:53 GMT -5 jonasbriggs said:

first is gas second is vacuum line. vacuum line is dry the gas line runs a bit of gas then stops leaking out. the problem may be in engine itself. is there any part of engine not carb that may make carb flood?

That's what I needed to hear.  Your petcock is fine. 

My only other guess is that the intake valve needs adjustment or something is wrong(not closing all the way).

If the intake valve is not closing completely, the intake charge could be forced back into the carb and the tube between the carb and airbox.

You said you tried 3 carbs and had the same problem. Its hard to imagine that all 3 carbs have a stuck float or needle and seat issues.

[greginisn]

I’m a bit stymied with this problem. From what I remember reading the intake snorkle gets flooded when attempting to start or just started. Not sure if it does start. But the intake manifold is NOT wet. As they say, WTF!

It’s not making much sense to me.  Did I read this all wrong or what?

Greg

[jackrides]

It's time to restart this scoot thread with a brief recap of current status and most recent changes. This cannot be as complex as it seems.

[scooterted]

Ive been following this thread.

A few things stick out to me.

1. You say you have spare parts, are these old carbs or new? If theyre old i would at least change the float parts and possibly polish the seat to make sure youre really getting a good seal. (I realize its unlikely to have 3 bad carbs but still)

2. I havent heard you say youve inspected float level. (I realize its unlikely to have 3 bad carbs but still)


3. I would eliminate the vacume fuel shutoff and replace it with a manual one. But thats just me.

4. Someone mentioned intake valve lash. It sounds plausable. Did you re check it?





Or, and this is kinda wild (and its similar to the intake valve lash theory posted somewhere above) But your cam has drastically shifted. Causing you to suck air into your exhaust and out your intake.

A simple test would be to remove the exhast and carb and crank it. Intake should only draw air in and exhaust should only expell it.

Edit: saw on the first post where you said you got suction too.

[GrumpyUnk]

Is it possible you have cross connected the vacuum line and the fuel line? The fuel supply line goes from the carburetor inlet port to the port connector closest to the fuel tank, and the vacuum line to the other.
If they had been cross connected somewhere, that would explain the fuel flowing freely and coming out the air filter box. A quick check for correct connection or leaky diaphragm it to connect the vacuum line to a MityVac or other vacuum source. If fuel starts to flow through the vacuum line, you have a poked diaphragm, or the wrong connector on the valve. If fuel also flows through the gas line, then you definitely have a pierced diaphragm as ZERO fuel should flow through the vacuum line.
If the float was stuck or the float valve leaky, you'd likely have fuel coming out the carb vent in addition to dripping from the air cleaner box. Fuel has to get above the float bowl to come out the air cleaner, and the vacuum port on the plastic inlet manifold is the next best inlet for flow.
tom

[jonasbriggs]

all connections are in correct order. this is not my first rodeo. I rebuilt my engine 5 times prior to problem. checked all 4 carbs and they are good. floats are where they suppose to be. not a speck of dirt or grime. timing aligned. all worked on 100cc bbk then I swapped engine from 50cc 100bbk to 49cc 66bbk cause it was quieter. tried swapping to 49cc same engine 100cc bbk no spark. swapped to 50cc got spark but won't start. redone 50cc engine to 100cc bbk which used to work but no go. downgraded 50cc engine to 66bbk no go. got spark fuel air compression. took all wire harness apart checked wiring all good. replaced all electrical parts still no go. it's 1500 bike and i so far invested 2000 in it. do not know why won't fire. tried all I could. please HELP! I dont know what else to do other than tossing it in the garbage!

[jonasbriggs]

if anyone is near martinsburg west virginia hit me up ill pay you to fix it. I'm in desperate need!

[GrumpyUnk]

all connections are in correct order. this is not my first rodeo.
Does this refer to the fuel/vacuum line connections?

I rebuilt my engine 5 times prior to problem.
Did the engine run each of the 5 times you rebuilt it? Did it run one time?

checked all 4 carbs and they are good. floats are where they suppose to be. not a speck of dirt or grime.
Checked that the floats closed and opened and were not fouled with dirt, but not the idle, and the 2 jet/emulsion tube assemblies? Did you remove and clean the jets? Did you clean the idle circuit, removing the idle mixture adjustment screw and spraying with carb cleaner?

timing aligned.
Cam timing or spark timing?

all worked on 100cc bbk then I swapped engine from 50cc 100bbk to 49cc 66bbk cause it was quieter.
All WHAT worked ?

tried swapping to 49cc same engine 100cc bbk no spark. swapped to 50cc got spark but won't start.
Tried swapping WHAT?

redone 50cc engine to 100cc bbk which used to work but no go.
Does this mean re-installed the 100cc piston & cylinder?

downgraded 50cc engine to 66bbk no go.
Is this the same 50cc engine?

got spark fuel air compression. took all wire harness apart checked wiring all good. replaced all electrical parts still no go.
If you had spark, why replace any electrical parts? Why take the wiring apart?

it's 1500 bike and i so far invested 2000 in it. do not know why won't fire. tried all I could. please HELP! I dont know what else to do other than tossing it in the garbage!

Have you checked that your flywheel (on the blower end of the crankshaft) has not sheared the Woodruff key that sets the spark timing? Have you checked that the 'pickup' that senses the flywheel position has not moved or come loose? Both of those things could/would make your spark happen when the piston was out of place.

With all the swapping around, it is hard to know what the current situation is, except that whatever engine, no matter if 49cc, 50cc, 66cc or 100cc, will not start. Right?

Your posts have confused me because there are so many swaps taking place that I have no idea what the problem is. I'd suggest leaving one of them together, and checking things.
Check that the piston is at TDC - Top Dead Center.
Look at the flywheel, especially the outer diameter. You should find a rectangle of metal mounted on the outer diameter. It should be around the 11-1 O'clock position, AFTER the pickup in rotation, as the spark is supposed to happen before TDC in rotation. If the metal tag is not 15-20 degrees PAST the pickup, then the flywheel has likely moved on the crankshaft. The little metal tag is sensed as the flywheel turns, and it is used to tell the CDI when to spark. It is supposed to pass by the sensor as the fly rotates(clockwise) before the piston gets to TDC. About 20 degrees, ballpark.
If all that is good, move on to the cam. Again, with piston at TDC, take a look at the holes in the cam sprocket. The large hole should be at the top, the two smaller holes lined up with the flat surface the cover seals to. If not, cam timing is incorrect, and the engine will run poorly or not at all.
If that's ok, move on to the carb. Disconnect one of the vacuum lines, and use a funnel, straw, or syringe to squirt about 1/2tsp of fuel into the intake. Crank the engine over, and if it fires for a few seconds, you have a fuel problem.
You stated, somewhere, you had spark, and then swapped all the electricals. Pull the spark plug, and reconnect the plug wire to the plug. Lay the plug on the engine so it touches clean metal. Kick the engine over while watching the plug gap. It should spark. If you get no spark, try another spark plug, kicking again. If still no spark, try another coil, and if still no spark, try swapping a new CDI.
If you have spark, flywheel timing is good, cam timing is good, the spark is good, and it still won't fire with a bit of fuel drizzled into the intake, you have a miracle engine. Kicking the engine over, with the key in RUN, the handlebar switch set to RUN, should allow spark, and should allow the engine to run w/o pulling on either brake lever.
tom