What is this and would it cause....

[Squiggles]

#24 in the pic

Carbs were cleaned and reassembled but #24 was noted to not seal well between the walls and #23


Issue is a high idle when the bike (83 GN250) gets hot. Idle's @ 1500 when cold, when warm it'll come back down to rest at 2500 and creep down to 1500, when hot it wont come down and sits 2500-3000

Thought maybe an intake / exhaust leak so i've checked the boot over and regasketed to the head, plenty of exhaust sealant for the pipes

Would this wee bugger be causing my issues?

[MSTRS]

I shouldn't think so. It's only an 'o'ring around the fuel shut off needle valve. But sounds like your bike is definitely sucking extra air somewhere, which will make it run lean/idle high

[paturoa]

is it running a standard air filer?

[Squiggles]

is it running a standard air filer?

yes and filter appears to be in good condition

cant find where it could be sucking extra air in

[WarlockNZ]

Have you checked the manifold between the carb and the cylinder ??

It could be cracked, that would explain the extra air.

[Wheeliemonsta]

Gidday,
The O-ring you refer (Item # 24) is very basically designed to be of a very slight interferance type fit, it performs a very basic task:

1: To act as a seal between the body of the carburettor & the "Seat" itself, what it does is prevent unfiltered fuel from getting into the float bowl by giving it no other path than to go through the filter gauze above the seat...

Without having the carb in front of me it's a difficult one to diagnose, but I'm suspecting you'll find the problem will be either with a damaged / delaminated or leaking diaphragm (Item # 7) or wear in the Needle Jet (Item # 26) & Jet Needle (Item # 16)

I'd start by having a good hard look at the diaphragm for any pin holes, tears or signs of delamination & other damage - then & only then when you are 100 % certain that the part is servicable woud I move further in the bowels of the carburettor...

Wear in the Needle Jet & Jet Needle is normally not detectable with the naked eye unless it's exterme - these two items must be replaced as a pair

If your the least bit sceptical about any of the component parts then either replace them or have a suitably qualified technician pass sentence on them, don't second guess anything...

The body of the carburettor needs to be absolutely scrupulosly clean before you start re-assembly & the only way to do that is shit loads of "Carb Clean" & a good uninterupted supply of compressed air...

If your able to, literally soak the carb body & associated jets etc etc overnight in the Carb Clean (after making sure all rubber components have been removed) & then deal to every orifice with the compressed air...

Inspect & reassemble every component in the manner above

Out of curiosity, how many k's has "Gina" done...?

Cheers

:rockon:

[Conquiztador]

Leaking needle valve (this is the one that is pushed up by the float to stop fuel from entering the carbi when the float chamber is filled to the required level). #23.

When bike was stationery she would run fine. But when used on the road and more vibration the needle valve would not fully close allowing too much petrol in to the carbi. This ment that the level inside the chamber was too high and the idle jet (that does never close) would suck in too much petrol resulting in higher idle.

My recommendation: New needle valve and seat and you might be on to a winner. Also not an expensive or tricky repair.

Good Luck

[Max Preload]

To act as a seal between the body of the carburettor & the "Seat" itself, what it does is prevent unfiltered fuel from getting into the float bowl by giving it no other path than to go through the filter gauze above the seat...

It does a bit more important job than that. If that seal (which I also assume is the seat seal to the carburettor body) leaks, the needle shutting off under the force of the float in the fuel will not prevent excess fuel from entering the float bowl because fuel will just by-pass the needle and come down the side if the seat thus causing a high fuel level.

[Squiggles]

So today i took the top off again and inspected the diaphragm, looked good to me, no pin holes, when i rolled the bike out of the shed, i noticed what appeared to be and smelled like gas dripping out the airbox drain (tank not connected yet, no fuel left in carb), this must be from before and in my backwards drop out the shed sloshed towards the drain... Not much gas, a thin layer in the airbox, and a wee bit on the ground

have attached the pictures


thoughts? will wait for reply's then go buy parts

[xwhatsit]

Leaking fuel while parked is usually a result of a leaking float valve. Could be dirt on the seat, or the valve or valve seat is worn out.

[Squiggles]

shes not getting any extra fuel while parked, tank is switched to off :blink:

edit: ah, i think i know where the fuel came from though, when i was removing the carb the twisting and turning let some out... that'll be where it came from :)

[Squiggles]

to the top with ten chars

[rogson]

I had the same symptoms that I eventually traced to a worn needle/needle jet.

You can diagnose if its a worn needle/needle jet by adjusting the needle position down as low as possible. Put the e-clip on the top groove, move the washer thats normally under the e-clip (i.e. on top of the spring) to above the e-clip and the nylon washer on top of that. If you don't have adjusting grooves in your needle you will need to stack washers/shims on top of the e-clip to achieve the same thing (model shops have suitable washers/shims).
Make sure you don't lower the needle to the point the spring is coil bound - the needle needs to be able to move around a little otherwise it will bind in the jet and prevent the slide from moving freely.

If the needle/needle jet is the problem the bike should now run cleanly off-idle and return to idle hot or cold, but will probably hesitate when accelerating through the mid-range (needle is now too lean in the mid-range). As the man earlier said - if worn, both needle and needle/jet (also called emulsion tube) must be replaced.

[Hanne]

Leaking needle valve (this is the one that is pushed up by the float to stop fuel from entering the carbi when the float chamber is filled to the required level). #23.

When bike was stationery she would run fine. But when used on the road and more vibration the needle valve would not fully close allowing too much petrol in to the carbi. This ment that the level inside the chamber was too high and the idle jet (that does never close) would suck in too much petrol resulting in higher idle.

My recommendation: New needle valve and seat and you might be on to a winner. Also not an expensive or tricky repair.

Good Luck

Im going with it probably being this, as when i swapped the diaphragm, needles etc off a carb that had been running fine the problem still occured

have ordered parts :)

-Squiggles (on his mrs' account)

[awayatc]

Hi, hope you got bike sorted out by now, but just in case...had similar issues with similar bike once (DR 250) turned out it was the inlet manifold.The rubber bit which is "glued' on to a steel plate (like an engine mount) was not 100 % sealing anymore....hard to see untill you aplly sideway force with manifold removed...
The way you describe what happened to your bike is exactly the same as what was wrong with mine...
Good luck

[awayatc]

Hi, hope you got bike sorted out by now, but just in case...had similar issues with similar bike once (DR 250) turned out it was the inlet manifold.The rubber bit which is "glued' on to a steel plate (like an engine mount) was not 100 % sealing anymore....hard to see untill you aplly sideway force with manifold removed...
The way you describe what happened to your bike is exactly the same as what was wrong with mine...
Good luck

[awayatc]

Im going with it probably being this, as when i swapped the diaphragm, needles etc off a carb that had been running fine the problem still occured

have ordered parts :)

-Squiggles (on his mrs' account)
Hi, hope you got bike sorted out by now, but just in case...had similar issues with similar bike once (DR 250) turned out it was the inlet manifold.The rubber bit which is "glued' on to a steel plate (like an engine mount) was not 100 % sealing anymore....hard to see untill you aplly sideway force with manifold removed...
The way you describe what happened to your bike is exactly the same as what was wrong with mine...
Good luck

[Katman]

As has already been said, the o ring around the needle valve seat can definately cause a problem. If the bike has been sitting unused for a long time the o ring can go hard and then (as awful truth has mentioned) will allowed fuel to seep past and will overflow the fuel bowl.