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I went ahead and ordered a new check valve...... hopefully I am getting the whole assembly. It is an OE Walbro part.
I am going to tear the carb back down if i have time tonight and remove the large welch plug and inspect the check valve.

I will see about something for the fuel line. Not sure just yet.

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I seem to just have a terrible time with Walbro carbs in general. Tillotsons never seem to give me any grief. I have a Homelite EZ with an HDC that I cant make run for a hill of beans. Had the carb apart a dozen times 2 different kits, it went from hot pulling fuel at all to at least it runs but it is erratic and not tunable at all.

Sent from my SM-G950U using Tapatalk
 
I went ahead and ordered a new check valve...... hopefully I am getting the whole assembly. It is an OE Walbro part.
I am going to tear the carb back down if i have time tonight and remove the large welch plug and inspect the check valve.

I will see about something for the fuel line. Not sure just yet.

Sent from my SM-G950U using Tapatalk

For the fuel line I'm yet to try it but I feel like a big rubber hose in the "firewall" with some standard line through that and that same bigger hose on the carb barb with the small hose pushed inside it.

I had a line that broke the barb end off so I cut the rest of the ribbed bits off and stuffed it inside some bigger rubber line "milk pulsation hose" and it doesn't leak at all
 
I seem to just have a terrible time with Walbro carbs in general. Tillotsons never seem to give me any grief. I have a Homelite EZ with an HDC that I cant make run for a hill of beans. Had the carb apart a dozen times 2 different kits, it went from hot pulling fuel at all to at least it runs but it is erratic and not tunable at all.

Sent from my SM-G950U using Tapatalk

Reminds me of an SDC on one of my 10-10. I must've had that thing apart 100 times. It'd run, wouldn't run, would leak gas so much that it would come out the muffler, wouldn't tune worth a $#@! - almost threw it in the trash out of frustration... Finally one day when I had it apart, one of the welch plugs literally fell out. :eek: Replaced that (firmly) and it's been going strong ever since! If it hadn't fallen out, it would probably be in the scrap bin right now, but it always seemed solid so I probably never would have thought it was the problem.

Good times!
 
So, someone thought it would be a good idea to unbolt what was left of the reed, slide it down to cover the hole and weld it on three sides!!!!!

Now that's wild. Slipped right past me. Didn't even notice it when I pulled the muffler to take a pic of the piston. Only ran it briefly before I drained it and boxed it up. Think I mentioned that it did seem a bit sluggish. Started right up, tho! LOL
 
Now that's wild. Slipped right past me. Didn't even notice it when I pulled the muffler to take a pic of the piston. Only ran it briefly before I drained it and boxed it up. Think I mentioned that it did seem a bit sluggish. Started right up, tho! LOL
I think the only reason it ran was because what was left of the reed was cracked and allowed it to flex just a little bit, not much mind you, but a little.

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I think the only reason it ran was because what was left of the reed was cracked and allowed it to flex just a little bit, not much mind you, but a little.

Sent from my SM-G950U using Tapatalk

Poge got you with the banana in the tailpipe joke, but for chainsaws... :laugh:
 
I seem to just have a terrible time with Walbro carbs in general. Tillotsons never seem to give me any grief. I have a Homelite EZ with an HDC that I cant make run for a hill of beans. Had the carb apart a dozen times 2 different kits, it went from hot pulling fuel at all to at least it runs but it is erratic and not tunable at all.

Sent from my SM-G950U using Tapatalk

What ignition is in the EZ?
 
It's my recent understanding that along with the two types of check valves, there are also thick and thin pump side gaskets for different SDC models. May want to check which carb you have to determine which gasket it requires.

SDC Pump Side Gaskets

Thick is for the steel cover and thin for the aluminum pump cover.
 
Brian, I took one apart today and found the number 251073, I measured it to be 17x35 mm but it would good to try and confirm it against that seal number.

Both seals are the same.

Mark
Thank You Mark. I have a 35 that is reving with the throttle closed so I figure it to be a bad seal

Brian
 
Somethings missing!!! Looks like going after the high speed check was the right move.
08eb48ce47f954ed731fa932eaa772a4.jpg
0cfb214b2cf5cff313f04d72c0461b95.jpg


Sent from my SM-G950U using Tapatalk
 
I went ahead and ordered a new check valve...... hopefully I am getting the whole assembly. It is an OE Walbro part.
I am going to tear the carb back down if i have time tonight and remove the large welch plug and inspect the check valve.

I will see about something for the fuel line. Not sure just yet.

Sent from my SM-G950U using Tapatalk

Somethings missing!!! Looks like going after the high speed check was the right move.
08eb48ce47f954ed731fa932eaa772a4.jpg
0cfb214b2cf5cff313f04d72c0461b95.jpg


Sent from my SM-G950U using Tapatalk
Tiny screen and the valve material. That would make it run afoul.
That other welch plug looks like a replacement?
 
It's that simple?
I noticed that on the sdc carburetors for the homelite saws mostly ,and if you use the thicker ones with the aluminum cover the location pegs won't reach the main body very well . The steel cover has a small transition slot and the thick gasket adds the volume to the pump where as the space is machined into the aluminum cover.
 
Good intel there. @fossil has a list of which models use which gaskets, (presumably with the corresponding pump covers), and also included some check valve info. Not sure he has it in a format for distribution yet, but I believe that was his intention.

That would be AWESOME if it comes to pdf. , I have some carb swap ideas to play with.
 
Good intel there. @fossil has a list of which models use which gaskets, (presumably with the corresponding pump covers), and also included some check valve info. Not sure he has it in a format for distribution yet, but I believe that was his intention.

Thanks for the prod Poge. I wan't sure if it would be of interest.


The best way to find out which pump side gasket to be used is to go onto the Walbro site and see which SDC carb takes which gasket. As you all know there is a thick one and a thin one and and the thick one is generally used on the steel pump cover carbs but there are a few exceptions.
And yes, the little tits on the carb are not tall enough in a few cases.

Here's a list (pdf file attached) which is incomplete as some of the carbs are not listed.
It gives the carbs I could locate info on and PN's and drawings for the thick and thin gaskets. You will need those gasket PN's if you use the Walbro parts lookup on their site.

There is a list at the end that also shows which carbs that I could locate which use the check valve diaphragm as well as the pump diaphragm on the pump side as there seems to be some confusion as to when both are used.

I am far from perfect but I think the list is good.
 

Attachments

  • Walbro SDC pump side gasket thick and thin PN's plus chk vlve diaphtagms.pdf.pdf
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