88 TRX250R Carb issue

[ddbyrd3]

I have a stock 88 TRX250R. The carb leaks out of the overflow tube.

I installed a new needle, I verified the floats do NOT fill with gas, I set the float height to 16mm per the book, and I cant get the carb to stop leaking out the overflow tube...

Has anyone seen this before?

Also, the needle I have, has a spring loaded tip that rest on the float arm. Are these stock or aftermarket floats..

[86 Quad R]

what is the condition of the seat itself aswell as the tube that is fixed to the bowl. i've seen those have pin holes in 'em. :eek:

[ddbyrd3]

The seat itself, based on my eyesite looks good. I took a Q-tip and cleaned it, it looks great...

I have a carb from an old 86 I use to have and I swapped the float bowl, and it still leaked. So I have to at least rule out the overflow tube.

[86 Quad R]

do you know if the carb was ever used with a metal tip seat? i've seen em get whollered out.

[ddbyrd3]

Have you ever heard of the brass seat coming loose in those carbs. It almost appeas as if it is leaking past the seat..

[ddbyrd3]

no I dont know if a metal tip has been used. When I pulled it apart it had the rubber tip needle in it. But who knows.

[86 Quad R]

i've never experienced it but is a remote possibility.

[ddbyrd3]

I am definatly scratching my head on this one...... makes no sence.

I have an 89 sitting next to my 88 I am about to start swapping parts to isolate the issue if need be..

[ddbyrd3]

Are the seats replaceable in these carbs?

[86 Quad R]

take and bench pressure test the delivery circuit and see if its seaping around the seat assembly. ;)

[ddbyrd3]

Using air pressure or liquid?

I did a similar test last night, I had the float bowl off, turned the carb upside down, connected the fuel line (full tank of fuel) and I would swear it was leaking around the brass seat.

Not scientific I know.. But I was curious.

I suppose I could insert my needle into the seat (WITHOUT THE FLOAT) regulate the air pressure and pressurize the fuel inlet and see if air gets past the needle....

[86 Quad R]

i'd use air. that way you can use a dish soap solution to make lil tiny bubbles in the area that is leakin' :cool:

you have a mighty vac?

http://www.mityvac.com/images/no_flash.gif

[ddbyrd3]

I will give that a shot..... makes the best sence....

I am feeling a new Keihin 34mm carb in the near future unfortunitly...

[wilkin250r]

What kind of air pressure are you using? I'm thinking 2 psi.

[ddbyrd3]

I wont be able to get around too it until Wednesday, but that is what I am thinking. I dont want to over simulate the pressure of the fuel pressing on the floats.

[86 Quad R]

Originally posted by ddbyrd3
I wont be able to get around too it until Wednesday, but that is what I am thinking. I dont want to over simulate the pressure of the fuel pressing on the floats.

'ats why i asked about the mityvac. :cool: otherwise you could make use of a blood pressure bulb or nipple'd ketchup bottle ect ect. :)

[slamdak8782]

I seem to remember there being a screw on the outside of the carb that if loosened would allow this to happen to clean out the bowl otherwise I believe your float is being stuck open in some way.

[86 Quad R]

Originally posted by slamdak8782
I seem to remember there being a screw on the outside of the carb that if loosened would allow this to happen to clean out the bowl otherwise I believe your float is being stuck open in some way.

nawt on the pj or pwk carbs. :cool:

[ddbyrd3]

Its dead!!! I get air around the needle. As soon as I applied low air pressure to a soap solution, bubbles blew everywhere...

Time for a new carb.....

Thanks for all your help..