hissing noise coming from carb intake manifold

[zip kart]

when I started up quad there was a hissing noise coming from the intake manifold where a pipe should connect to the side of the mani ,never had this problem before
looks like there was a blue flame comin out of it any ideas?

 

[jamyers]

Re-connect the pipe? If whatever it is isn't needed, plug the hole.

Shouldn't be any flame of any kind inside there, that's odd.

 

[zip kart]

there wasnt ever anything connected to it and never had any problem before
ye its kinda strange and ye there was a small blue gush that was comin out of the plug hole
and when the quad is ticking over it splutters and pops
and if i drive it it has no power it splutters


checked spark plug and the electrode was browny orange ?

 

[jamyers]

Got a pic?

 

[zip kart]

il get some pictures 2moro as its locked up in d shed

 

[Doc Sprocket]

I swear we talked about the hissing before. Post a pic of the hole.

 

[zip kart]

will do

 

[Doc Sprocket]

Meantime- NO flame of any kind should be anywhere near your intake manifold. BYOFE.

Also- If there's a port in the intake manifold, it would likely be a vacuum port. Used perhaps to drive a pulse pump. Also, some bikes use a pulse-driven petcock- It's an automatic fuel valve. Engine pulses allow fuel flow. When engine stops, so does the fuel. So- If that's a vacuum port, the hissing is simply vacuum. Either connect it to what it's supposed to be connected to, or plug it tight. Please note-

A vacuum leak WILL cause your engine to run like st! Plug it and try.

 

[jamyers]

BYOFE.

Huh? :scratches head:

 

[Doc Sprocket]

Bring Your Own Fire Extinguisher!!! Bwahahahahahaaaaa!

 

[zip kart]

ok heres the picture of the intake manifold ,
the hissing comes out through the connection where there was once something connected to it ,never had this problem before and there was never anything connected to it


and heres a picture of the spark plug now
also i need to re tread the head ,because spark plug wont thighten fully will i have to take the whole engine apart ?

 

[ML-TOYS]

What was connected to it and why is it not there now. Also if your plug wont tighten then it will run bad with the loss of compression.

 

[zip kart]

there was noting connected to it ever
and i need to re-tread the head because the plug wont tighten

 

[jamyers]

There had to be SOMETHING either on or in there, and it's gone now. Around here I get mud-dauber or bug nests in every tiny hole, hose, and pipe that's open - may have been a bug-nest that finally got sucked in and burned up.

That plug looks fine color-wise.

If the threads are stripped in the head you've got a problem. You can't just re-thread them the same size, the plug will just pull out again. You'll need a thread repair kit, either call your local parts place or look online for one that matches your sparkplug threads. Google "stripped spark plug repair" for a ton of info...

"They" say you need to pull the head, but IF you're paranoidly-careful, you can do it in place. Best if you can get the sparkplug hole aimed downwards so that gravity is on your side, and the piston at TDC on the compression stroke. Load up the tap with a ton of wheel bearing grease at the tip and between the flutes, TAKE YOUR TIME (you've got to get every piece of aluminum shaving from going/staying in the cylinder). If you have an air compressor with a nozzle that'll actually go inside the hole, that's a great tool.

Once you tap the head oversized, you'll put an insert in there that'll bring it back to stock thread size, often with some threadlocker (be sure and let it set according to directions).

Just to make absolutely sure there's no metal particles left in the cylinder, I'd back the piston down about halfway and flood/flush the cylinder out a time or two of lighter oil like ATF and compressed air. Prepare for a huge mess, and a ton of oil-smoke when you first start it back up.

 

[Doc Sprocket]

Again I say- A vacuum leak will cause an engine to run like spit. Now- There MUST have been something connected to that port, OR a cap on it. No manufacturer (even Chinese) is going to leave a port off the intake open to the elements. Seal it. Maybe even the port was added by the previous owner. Doesn't matter. Seal it.

 

[DJEEPER]

I bet it goes to a port on the side of the carb. Many carbs use manifold pressure to pump fuel.

 

[Doc Sprocket]

the connection where there was once something connected to it ,never had this problem before and there was never anything connected to it

Dood... Whut?

 

[zbuck]

Is that the original engine for the quad. Is the gas tank divorced from the engine? If so that is a pulse fitting in the intake manifold for a fuel pump. On second though, what kind of fuel petcock is on the quad? That could be for a hose to the petcock with a check valve to provide vacuum for opening to provide fuel and closing to shut off fuel from the petcock.

 

[DJEEPER]

Yup, thats what I was thinking.

Inflow, outflow and the vacuum actuator that opens the valve on engine pulse. Thus, no engine pulse, no need for fuel flow, the valve closes.

 

[zip kart]

heres the pit cock
and theres was never anything attached to the connection on the intake mani ,theres was a little bit of rubber that must of being what was there before i had quad
i never had any problems with this before