rleasure

My Feedback: (8)

I've got a Walbro SDC carb on a Quadra 75M that is giving me fits. A little background. This engine came in a Ziroli Corsair that I purchased. The engine hadn't been run in about three years. I replaced the tank, all fuel lines, spark plug and rebuilt the carb. Initially, I could not get the engine to go to full throttle. Once above about half throttle, it would die. Hooking the engine straight to my gas can, it would run just fine. I went back through the tank, eliminated the filter and the T for the fuel dot and tried again. No luck, however, I did notice that the fuel in the tank was foaming badly. (BTW, I am using a 32:1 mix) So I pulled the tank out and added more foam around it. This eliminated the foaming problem. After backing the low and high speed needles waaaay out, I was able to get the engine to run at full throttle, but it would "surge", dropping rpm almost to idle then run back up. I took the low speed needle out further and got rid of most of the surge. I then noticed that fuel was dripping from the carb while running. I pulled the carb off to re-tighten the screws. While doing this, I noticed that the gasket between the carb and the intake manifold appeared to be on incorrectly. There is a little hole in the gasket, and in the carb, that was not lined up. I fixed this, put the engine back together, AND IT GOT WORSE!!! Would die at 1/4 throttle.

So, I cranked down the needles again and started over. Backed both high and low out again and got the engine to run, no "surge", good idle, etc. So, I decided to set the low speed needle. I started cranking it down and punching the throttle from idle to full, repeating the process until the engine died in transition, at which point I was going to back out an 1/8th turn and work on the high speed needle. Well, I've got the low speed needle cranked all the way down, and it still will not die in transition!

Help!! I'm lost. This is my first gas engine.

TIA,
Rick L.

tommy157

My Feedback: (1)

Have been battling a Walbro Carb on an older Sachs 63cc for days. Finally replaced plug and all the problems went away. set both needles at 1 1/2 turns out and make small adjustments.I was told that the low speed will have an effect on the high speed as well so keep track of your adjustments so you can go back to a previous adjustment. You mentioned you overhauled the carburetor but went back and found a gasket on wrong. I would suggest you take the carb to a local small engine shop and let them check it out, might cost you but they should know all about this carb..If you decide not to then make sure the float is set correctly I was told it is set level lay a straight edge over body and bend tab till it just touches straight edge. Did you replace needle? If not might be a good idea..
Good Luck!!

Antique

My Feedback: (4)

If the engine has not been run for 3 years the carb needs to be rebuilt...Get a $3.81 carb diaphragm kit, D10 SDC...Take the cast cover off the carb...Put the diaphragm on the carb with the gasket on top...Take the steel cover off..The lever should be flush with the casting next to it, not the top of the carb...Put the gasket on the carb, put the diaphragm on top..There may be a fork in the lever, be sure the diaphragm is hooked into the fork...Open both needles 2 turns and start over..Set the high speed first....

tommy157

My Feedback: (1)

Thanks for correcting me RCIGN1 on the float setting.I was told that and set mine by it and it seems to be working fine should I go back and correct the setting? Would it have a big effect?

rleasure

My Feedback: (8)

I did do the carb rebuild. However, the rebuild kit I got came with many more gaskets then were in the existing carb. I am starting to wonder if someone else has been into this carb. I've never done a carb rebuild before, and I am not even sure what eveything is called. I replaced all gaskets that were in the carb, the lever, the pump impeller (?), and all the gaskets on the other side. One thing I did notice that made me think twice, I had at least 3 or 4 gaskets that looked like they went on the side opposite of the diaphram. Two of them had a circle cut-out of them, one didn't. The part that was in the carb had the circle blocked, so that is what I put back in.

I am starting to wonder if the diaphram and lever got screwed up when I put it back together. Uneven or inefficient pumping would probably explain the behavior I am seeing.

Sorry for my ignorance. I printed out the exploded view drawings of this carb today at work and I plan on spending the weekend learning what everything is called so I can seem a little more knowledgeable when asking for help.

Thanks for your answers,
Rick L.

Antique

My Feedback: (4)

Old saying..If it ain't broke don't fix it..But--------
Walbro lever settings...
HDA...Flush with the carb body
SDC, WA, WJ, WT, WTA...Flush with the plate next to it
WB...3/64 to 1/16 below the top surface of the carb body

Antique

My Feedback: (4)

Rebuild kits are made to be used on many different versions of the same carb...Safest way to rebuild is to take off one cover at a time and replace only the same parts, IN THE SAME ORDER..Throw the rest away...

rleasure

My Feedback: (8)

How do I set the lever? If I remember correctly, mine has a spring under it. With the exception of bending it, I didn't see any way to adjust it.

BTW, that's exactly how I did the rebuild. I kind of figured it was a general kit.

Thanks again,
Rick L.

Antique

My Feedback: (4)

That's it...Bend it up or gently hold the needle against the seat and bend it down...

rleasure

My Feedback: (8)

I got it fixed. Turns out you not only have to pay attention to the pattern of the gaskets when you do a rebuild, but the thickness. There were two gaskets in the rebuild kit for the pump side of the carb. When I compared the one I put on with the one I took off it was the wrong thickness. Put the thinner one on and it runs like a dream! Glad I kept the old gasket. Being a pack rat comes in handy some times.

Thanks for everyones help and advice,
Rick L.

PHD

My Feedback: (1)

I am glad you got to fix it your self . We learn something every day and this is what makes this hobby fun . If it ant fixed it ant flyin

Rocketeer10

Just something to pass along here. Make sure to check that your case and cylinder bolts are tight! I had a Quadra 52xl, that ran great! Then overnight it seems it would not run right and then would not start except for a direct prime of gas squirted in the carb. It would burble and then die... I found that the cylinder bolts had loosed up and it was leaking air! Or should I say, it was not directing pulse pressure to the carb and so the carb was not pumping!

Sometimes it is the craziest things that go wrong!
Just my 2 Cents
GY