bob_nj

My Feedback: (62)

The current carb on my 3W 140 is a Walbro WCA7 815. I can post pictures if necessary. What can I replace it with, or do I have to directly replace it?
I’m not sure if it’s just worn out, but it’scome very inconsistent and I need to make a move. Can’t trust it anymore.

What does a new carb go for these days?
Thanks_bob

Antique

My Feedback: (4)

No such thing as a WCA7, it's a WGA7..Carbs don't just go bad, the diaphragms get stiff...A new carb kit is about $5....

bob_nj

My Feedback: (62)

Thanks, and you're right about the "G" What's in a carb kit? I can handle the diaphram replacement etc., but are there other critical parts that I need to know about? I am familiar with glow, but not as familiar with gas engines.
Thanks for the reply_bob

Antique

My Feedback: (4)

No critical parts, just 2 diaphragms and 2 gaskets....One of the diaphragms hooks under the inlet needle, you have to be careful taking it off and putting the new one on...The lever that lifts the inlet needle must be flush to the casting next to it....

bob_nj

My Feedback: (62)

Thanks, have a new kit on the way. Found some trash in the screen area of the carb today. Hope that was the problem. Will rebuild and let you know_bob

Rodney

The nice thing about Walbro carbs is their reliability. I have only had to replace one, a carb on my 72cc engine did finally wear enough so that the rotating plate (not sure what they call it) bearings were so worn that they were egg shapped after a few hundred hours of use --12 years with at least a hundred flights a year. I do have to clean the screen every few months though, no matter how much I filter the fuel, some fine dust seems to get into the screen. To clean it, I just pick it out with a small pin, hold it in forceps and light it with a match or lighter to burn off the fuss then rinse well in fresh fuel and reinstall it. The only time I've had to put in a full carb kit was to get another engine that had sat idle a long time to run as the gaskets were very stiff and brittle.

bob_nj

My Feedback: (62)

Thanks. Do you guys mess much with pop off pressures or fulcrum heights?
There was a thread on the SA list where guys were finding the pressures to be almost double what they should. This makes for some dubious engine runs at best[:-] Take care_bob

Antique

My Feedback: (4)

Popoff pressures and fulcrum heights are not made to be adjusted, Walbro knows best...If changing these fixes a problem it was something else in the first place...

bob_nj

My Feedback: (62)

That may be, but just like anything else mechanical, there is room for, and often are errors. All I'm saying is that some flyers were checking their pressures and finding them to be way too high causing some of the persistent and consistent rich/lean running problems so often posted to the boards. Lots of these were new units from the factory/distributor. When the pressures were high, the recommended needle settings don't often work and need to be opened more.
The kart, hanglide and jet ski guys tweak and adjust for better runs. I forget who it was on this board that says how surprised he is that people don't adjust their needles. After all, that's what they are there for.
If needles can and need to be adjusted, why not other things?
Again, thanks for the help_bob

GeraldRosebery

My Feedback: (14)

From my own experiences I feel that the way Walbros work is more subtle than most of us believe. I have had major engine problems associated with almost new carbs. A rebuild fixed the problem every time restoring the carb to its original settings and condition. If people are thinking that "maybe it's the carb" I say get a full kit for $7-$8 and rebuild it. After doing six carbs myself, it only takes about 15 minutes including blasting out the ports and jets with cleaner and letting it dry. It's really worth the investment of a couple of bucks and the time.

rmh

No one mentioned that the throttle plate canbe severely damaged --if one removes the spring on the shaft - I have seen these which rattle back and forth until the plate is flattened at the end of the shaft.-- this makes a air leak that simply will not allow the engine to shut off - or idle at correct mix.
Nobody else ever fix worn carbs?
I silver solder the plate - which is a braze - then re shape with a file to original dimensions --OR replace the plate.