Hi Guys, I have discussed this with some of you but decided to put it on the table for all the engine guru's here. It seems the WYK series carbs are old stock and can't be found. Can someone suggest what carb to use to replace the stock carb on the B&S 34cc or 40cc 4-strokes? I would like to be able to adjust it and have one a little bigger bore then the stock carb. also. Thanks to everyone for your help.

John, I just talked to V.E. Petersen Company in Walbridge, Ohio telephone number 800-537-6212. They currently have 8 WYK-61 carbs in stock. I have this one on my Honda GX31 and it works great. Let us know what you find.

Thanks Tim, I didn't ask them about that carb. I did ask them about the WYK138 and they said they sold the last one on 6/06 and didn't have any more. So, this carb will bolt onto the B&S the same way it does to the Honda? Did you talk to a guy named Harry?

John I didn't get the name of the guy I talked to. My WYK bolts right up to the stock manifold on the Honda. I would assume it would on yours too. These carbs do seem to have a more precise or crisp throttle control. I can say that by having the lw speed needle adjustment that I was able to get the engine to run much smoother. Time will tell as I am building the wing of my Fokker DVIII by Glenn Torrance and will start the fuse this week also. Can't wait to get this thing installed.

I called over a dozen places looking for a wyk 38-1 to no avail.I then sent an e-mail directly to walbro who replied they were available but when I went to their website to order one it said "special order only". The good news is that they have not been discontinued, at least to everyone I corresponded with. I may try a wyk-61 just to get the benefit of having high and low needles.

J

PS: Tim, would love to see some pics of your DVIII!

The carb is a WYK-138 you need to ask for. Look back at my prior posts and I give the number of the distributor I use. He had 8 today. I will also post a picture or two of the construction process of my DVIII. May start a new thread.

I have had good performance out of a WYK-16-1 on several Honda GX31 4 strokes.

That is the carb I originally wanted for my GX31. When I tried to get one I was told by several suppliers that it is no longer available. So I bought the WYK-61 a 9mm carb and it runs well. I also bought a WYK-138 which is a 10mm carb but haven't run it yet. How many RPM and what prop are you running Motorhd?

Guy's, What is the bore/venturi size of the stock carb on the GX31/35 and the B&S 34cc? Is the 9mm carb bigger or are you just getting the WYK for the adjustment needles?

The B&S 34 and 40cc stock carb is 9mm.

Tim, does wyk138 have a primer bulb?

Thanks

The stock GX31 carbs were WYL series and were 8.5mm. The intake manifold bore is smaller than the cylinder intake bore. You can ream the manifold to match the cylinder and probably gain some power. I will be doing this to mine. I would also like to make a new manifold to rotate the throttle linkage for an inline shot to the servo but there may be an issue with the pulse port hole. Time will tell. Main reason for changing carbs is the low needle adjustment. Also a little more carb gave it more power.

Both the WYK-138 and WYK-61 have primer bulbs. I may have had a typo on the WYK-138, I meant WYK-137. The WYK-138 is a 13.5mm carb and way too big for these engines. Very sorry for the error.[X(][>:][:@]

Tim, Do you know anything about the WYL-19-1 carb? I found some on Ebay that are used for the Shindawa(spelling?) weedwackers. I'll have to look for WYK-137 now.

Found the WYK-137 at SPEW for $61.

Looks like it only has one adjustment like the stock one. Try this link.

http://wem.walbro.com/walbro/product...9-1&Series=WYL

The wyl19-1 is the stock carb on the Briggs.

Thanks for the info and correction Tim.

Okay guy's thanks. Looks like the 137 is the one to try. Can't see buying another 9mm.

Just ordered a wyk-137.With that and my Honda GX35 coming soon,it will be like X-mas in September for me.I can't wait to start playing with my new toys.

Thanks for all the helpful info.

J

John, did you order it from SPEW?

Just ordered mine also. Gees, the carb cost almost as much as the engine! It's going to be a cool project. Tim, what are you using for oil? Sorry if I missed it someplace.

Not a Walbro carb, but I found (3) of these on eBay last week. They are a Zama RB-P25 rotary carb. Got them for $19 shipped for all three. I took a chance because they were cheap.

They have a 10.5 mm venturi and bolt to the manifold of my Ryobi 26cc 4-cycle perfectly. The manifold opening is 11.44 mm, so there is no overlap/restriction.

According to the Zama website, this carb is original equipment on the Cub Cadet 3075 trimmer. I believe that these were a 2-stroke with 25cc.

I haven't run it yet- just waiting on some engine conversion parts to get here. I'm not out much if it doesn't work.

Hope this helps!
John

Thanks,very interesting.
If they fit on a Ryobi, they should fit on a Briggs as well.If three is too many for you I'll take one off your hands!

J

Sure J- how does $10 shipped sound for one? Send me a email or PM.

John

I had Pennzoil 15W40 on the shelf so I used that. I am going to switch over to synthetic when I change it. Actually Harley-Davidson Syn oil. Designed for air cooled engines so I think it will be perfect.

FWIW,I am using Castrol All-Synthetic 5W-30.Doesn't it sound odd to be saying "changing the oil" when referring to your RC plane?Another is"Yeah,I'm going to fly it,I'm just letting the engine warm up".