Tips on swapping a check valve in HDA 268A?

[Nutball]

I have a 590 that isn't idling properly. I think it's the check valve. I tried cleaning the carb, and ended up blowing the little rubber piece out. It's shaped like a potato chip, so I think it may not be sealing properly. I put it back in, but the saw idles leaner over time and will accelerate like it is lean. Richening the needle compensates, but it leans out again and is a bit unstable at idle, so I think it's the check valve.

So, how do I fix this carb?

 

[av8or3]

The check valves are available on e-bay. About $15.
When you have the new valve in hand, start by popping out the clip used to hold the screen in place and then a small screwdriver will pop out the brass ring. Then put the new rubber disc in and press in the new brass ring (w/ the screen in place) in over top of it. I’ll send out a pic of the new check valve when I find it. Pretty sure I got some.

 

[Nutball]

And you are sure that kit fits my carb? Only one of the 3 pieces there look like what I need (the black part). I don't know of any clip or screen. As far as I know it might be one whole jet/check valve combo. I figured I'd need a whole new one of them brass bullet looking things.

Is there a cap that pops off the end?

 

[Red97]

And you are sure that kit fits my carb? Only one of the 3 pieces there look like what I need (the black part). I don't know of any clip or screen. As far as I know it might be one whole jet/check valve combo. I figured I'd need a whole new one of them brass bullet looking things.

Is there a cap that pops off the end?

View attachment 253792

That is the "nozzle" in the carb diagrams. Pound it through into the bore, and install a new one.

I like to Use the husky part. From hda 191.

 

[Lightning Performance]

That is the "nozzle" in the carb diagrams. Pound it through into the bore, and install a new one.

I like to Use the husky part. From hda 191.

Is it a lower spring rate that the oe one?

 

[Nutball]

That is the "nozzle" in the carb diagrams. Pound it through into the bore, and install a new one.

I like to Use the husky part. From hda 191.

Kinda stupid Echo and Walbro doesn't list that part for Echo carbs. Is the part for the 191 a #58 jet or close? I hope so. I'll give it a try.

 

[av8or3]

And you are sure that kit fits my carb? Only one of the 3 pieces there look like what I need (the black part). I don't know of any clip or screen. As far as I know it might be one whole jet/check valve combo. I figured I'd need a whole new one of them brass bullet looking things.

Is there a cap that pops off the end?

View attachment 253792

Naw, sorry got my carbs mixed up. This would be accessible from under the diaphragm. It sits under the spring for the fuel metering diaphragm.

 

[Nutball]

It seemed a little hard to find the right nozzle, they appear to be low in stock too, but I found one that is compatible. No bypass jet on it, and it has the fiberglass valve instead of rubber. I wrote down the dimensions in case I ever feel like trying to make my own if I ever needed one. It's stupid having to buy a $100 carb to fix a $5 problem.

 

[kneedeepinsaws]

It seemed a little hard to find the right nozzle, they appear to be low in stock too, but I found one that is compatible. No bypass jet on it, and it has the fiberglass valve instead of rubber. I wrote down the dimensions in case I ever feel like trying to make my own if I ever needed one. It's stupid having to buy a $100 carb to fix a $5 problem.

It is until you work with an at12 carb from a 550.

bought the nozzle through Dealer about 15$. It only comes out one way, and will not push through to the bore... started drilling and then used an agressive screw combined with a 3/8 nut and some washers/fenders to pull it out using the drill. Didnt line up the nut properly, broke the nozzle in half.
Ended up drilling some more but part of the sheet screw was in there, went thru 6 drill bits to get enough of a hole to bite on again.
Pulled it out, noticed that i took some edge off of the Carb body for the nozzle.
Put new one in, sealed up edge with poxy...


WHAT A PAIN.

so before you go doing it, lol, learn from my mistakes and also check your tank vent cause that has the same symptoms! You can do a tank vent in 10 minutes with far less swearing and blood pressure!

 

[Nutball]

So, a tank vent would allow full throttle cutting, but a continuously leaning idle? I think this nozzle will push into the bore, it's short, and the bore is large, but thanks for the warning.

 

[kneedeepinsaws]

So, a tank vent would allow full throttle cutting, but a continuously leaning idle? I think this nozzle will push into the bore, it's short, and the bore is large, but thanks for the warning.

No it wont, there i go again not reading all the info.
I was referring to the problems of leaning out at idle and trying to compensate with tuning.

 

[drf256]

So, a tank vent would allow full throttle cutting, but a continuously leaning idle? I think this nozzle will push into the bore, it's short, and the bore is large, but thanks for the warning.

If you need a nozzle let me know. I still have donor 144/120 HDA’s here that have been used for 198/9 to 87 spec conversions. The nozzles are still in them. Found that they are good to steal nozzles from for 620P carb conversions, yet another use for the undersized 261/262 carb.

They don’t have the bypass hole drilled in them.