One last problem: The carb! By FACE PLANT FOR LIFE (Read 1,922 times)

[FACE PLANT FOR LIFE]

After countless hours of working on my dad's bike, we are nearing completion of it. We helicoiled the head so that we could put a spark plug in, so that is now fixed. So anyways, we tried to start it, and it FAILED miserably. At first we weren't getting any fuel from the gas tank. We primed the carb with fuel and cranked it over, that got vacuum going and now we have fuel going to the carb. Only problem now is that the carb just dumps whatever fuel is has right out the overflow, so it never gets to the engine, and as such, never starts! Why would a carb be dumping all it's fuel out the overflow?

PS: If you forgot to put a head gasket on, would the bike have compression? My dad has a sneaking suspicion that he forgot to put on the head gasket/failed to put on a new head gasket despite the fact that he took apart the bike just to put a new one on

[Deleted]

the carb could be doing that because of a stuck float that isn't shutting off or a bad needle/seat not sealing.

it might have a little compression but there would be major leaks and you would definitely hear the hissing. it probably wouldn't even start without a gasket.

[Alleyoop]

Yes, if it is overflowing out of the top vent hose the float and shut off valve is not sealing and fuel just keeps coming into the carb bowl.
So take the carb off and the carb bowl and clean out the fuel inlet where the valve goes in and seals the fuel inlet.

As far a compression if you have a gauge check it, if no gauge take take the plug out and stick your finger in the hole nice and snug and crank it, if it has descent compression it will move your finger off the hole. If you just feel some pressure on your finger then you have low compression.
Alleyoop

[Alleyoop]

Forgot to mention on checking the compression YOU HAVE TO HOLD the THROTTLE WIDE OPEN otherwise you will get low compression.
Alleyoop

[tvnacman]

put some gas in a spray paint can cap 1 or 2 oz let the vac line suck it in see if you can get a sputter out of it .

John

[Alleyoop]

No John, first thing to fix is the overflowing of the carb right now the motor is flooded with fuel.
If he takes the plug out and cranks he will have gas squirt out of the plug hole.
Alleyoop

[Bashan]

Yes, all of that on the head gasket, it won't work without it. But two things, you can see it!

It's either there or it isn't. Also, if that gasket isn't in there the whole tower is not spaced properly and the stroke and compression ratio are trashed. It will not work. They even say don't use gasket treat because it will affect the spacing. I use the copper spray and it seems to work, but just a thin coat.

[FACE PLANT FOR LIFE]

Well, that didn't work out as expected. We took the carb apart and cleaned it thoroughly, and checked on the float and needle, and they were working as expected (sealing when full and vice versa). So why would the carb be dumping fuel if it isn't flooding?

[Alleyoop]

Where is it dumping fuel out of the VENT hose marked on this carb or elsewhere?
Alleyoop

[FACE PLANT FOR LIFE]

It is coming of the carb bowl drain. It is leaking with extreme pressure, also (nothing we can do to stop it).

[Alleyoop]

Ah, ok now the question is does your carb have that screw that you see in the picture or is the drain hose like this picture:

Alleyoop

[FACE PLANT FOR LIFE]

It has a drain hose. The drain hose is...missing the screw...well that would do it...huh..Any idea where I can get another screw for it?

[Alleyoop]

HAHAHAHA, know we can get it fixed. To stop it Either put another hose on and BEND IT OVER AND ZIP TIE or take the hose off and take the wiring off of it and then bend it over and zip tie it. You will never use that to drain the bowl trust me. They just cause more problems than they are worth.

Or take the hose off and go to the hardware store and get a screw that will screw into it. Then also get some silicone or something and put a dab on the screw after you screw it in. They tend to vibrate loose and fall out. That is why i say to just bend hose and zip tie.
Alleyoop

[FACE PLANT FOR LIFE]

I'll make sure to do that if it ever gets above 40 degrees here! Too cold to work on the scooter now!!

[FACE PLANT FOR LIFE]

This darned thing still won't start. Ziptied the fuel drain line and the carb is no longer losing fuel. Everything is hooked up correctly to the best of my knowledge. Fuel is hooked up to the fuel inlet, and the vacuum line is functioning correctly (fuel is being pulled). The fuel gets to the filter, and then the filter fills up. The filter is completely full, with no fluctuation, as if the carb isn't getting the fuel! Why?

Edit: Just in case, I bypassed the fuel filter, still no difference. I have no idea what's happening at this point. Is it time to take the carb apart and clean it again?