I am currently working on modifying a ryobi engine (it is actually out of a green machine trimmer, it doesn't have the standard ryobi carb, but everything else is the same) for aircraft use. The carb I have only has an 8mm venturi and only 1 needle valve so I really could use a different one.
according to this thread [link=http://www.rcuniverse.com/forum/m_4886237/anchors_4886237/mpage_1/key_ryobi/anchor/tm.htm#4886237]http://www.rcuniverse.com/forum/m_4886237/anchors_4886237/mpage_1/key_ryobi/anchor/tm.htm#4886237[/link]
I should be looking for a carb with a 26/64" (10mm) diameter.

I did some searching on ebay for all the walbro parts listed with part numbers and only found one around there.
WA-229 = 9.52mm (this is close, but it only has one needle valve, would this work for our needs?)

I did some searching around walbros site to find some that should work, and can be ordered, I didn't find any at 10mm, but I found several at 9.53, there were also a few at 11.11, I thought it best to go smaller and be safe than larger and risk flooding. They are quite pricey.
WT-112 $52.65
WT-142 44.82
WT-364 56.03
WT-654 42.00

I got tired of searching...

So I guess my question is, what model carb are you guys using and where did you get it?

PS.. If I knew then what i know now.. I would have just built a complete modified engine from jagengines.com for $178 plus shipping or from wackerengines.com (call for availability and pricing)

Either the 9.5 or the 11mm carb would be fine, but you definitely want two needles for adjustment. The 9.5 would favor a lower rpm range and a bigger prop, with the 11mm going in the other direction, but really, either size carb would work fine.

Do a search on E-bay. Some of the guys here have found really good deals on carbs there.

AV8TOR

Does this one look good?
[link=http://wem.walbro.com/walbro/product2.asp?Series=WT&partnum=WT%2D273%2D1]Walbro WT-273[/link]
I hope so... I just e-bayed it for $13 delivered.

Should be fine.

AV8TOR

Coolbean,
One big difference between the 9.5mm and 11mm is the throttle bore. The 9.5mm has a 1/2" bore and the 11mm has a 5/8ths" throttle bore which matches the backplate manifold.

Dave

you can also go to your local lawnmower repair shop and ask them for some used two needle carb, they usually are cool about giving these away just tell them what you plan to use it for.

I called around to the shops before I checked ebay. They all said they don't have any used parts available. I'm pretty sure the one I'm ordering will be good enough.