Echo 28CC engine
 

I found this on Fleebay for $15.00 and thought it could make a good conversion. The Zenoah carb block fits with little modification and I have a Bennett muffler. What I need help with is what size carb would work?

RE: Echo 28CC engine
 

11.2mm would be ideal. This would be a Walbro with a "28" cast into the venturi. The usual prop would be a 18 X 8

They run pretty good with a "24"

With a smaller prop like a 16 X 8 they could use a 1/2" or "32" Walbro

The "SB" in the part number means it is a short block for several different applications

RE: Echo 28CC engine
 

Thanks for the reply. I have one that should work WT263. I was thinking it would be a bit small for a 28cc.

RE: Echo 28CC engine
 

Nice, new and clean.

RE: Echo 28CC engine
 

Starting to look like something.

Question....... Should I be using the thick black gasket between the cylinder and the block or just sealant?

RE: Echo 28CC engine
 

The desired ultimate goal is to achieve .020" squish clearance between between the piston and head.

You can place solder strips on four corners of the piston and measure how thick the solder was compressed.

You may need the base gasket and it may be better to remove it?

Well after two years I'm ready to try and finish this engine up.

Echos are great engines and I really like them. However, if that is not a "twin needle" carburetor with both a high and low adjustment needle, you will need to change it for one that is. They make them both in the standard butterfly throttle type, and the rotary type like yours as well. Either one will work fine as long as it has both needles to adjust. Most of the rotary carbs like yours don't have dual needles unfortunately.

If yours doesn't have dual needles and you want to stick with the rotary style carb, try DavesMotors.com I agree with W8YE's size recommendation.

AV8TOR

I have used the rotary barrel type. It worked good. There are RB carbs, some with one needle & some with two needles. If you do not have good luck go to a carb that has a throttle plate. Most have 2 needles..one is Hi speed other is low end fuel adjustment.

One thing I liked about the rotary barrel is that the mid range does not have the "burble" in the mid range.

The plan for this engine was to convert it as inexpensive as possible using off the shelf parts. Thus the reason why it took so long. It also went way over budget because allot of trial and error went into selecting parts.
The most problematic issue was the carb. The ECHO insulator only fits the WYK series Walbro and at the time all I was able to find were the single needle types. I tried modifying a Zenoah block to fit but I didn't think there was going to be enough meet left to get a good seal. Thats when the project stalled and was put on the shelf.

About the time AV8TOR started this thread http://www.rcuniverse.com/forum/engi...ary-carbs.html I found a WYK 33 and got things back on track. The only thing left to do is install the ignition sensor and tighten things up.

The carb is a WYK 378 with a 10.5 mm barrel, a HS needle on the side and a low speed under the cap on the bottom/top. I also have a 12.2 mm carb to try if this does not work out.
The idea was to try to get the best mid range with the largest prop I can get away with. A little prop spinning real fast isn't what I'm after.

http://www.ereplacementparts.com/ima...197-1_WW_1.gif = parts breakdown

Well it runs. http://youtu.be/fpaZFcU5p6w
I'm not sure of the RPMs yet.

It sounds like you may have too much prop on it or your carb is not set right yet? Just guessing. Good job....clean & nice.

I was just happy to see it come to life and took the video. It was still way to lean on the top end.
The engine has about 4-5oz of gas through it now and seems to start and transition to full ok. Time to figure out the throttle linkage and mount it on the plane.

A throttle curve will help too. Example...set the furthest point of throw at full RPM...any extra throw does nothing. Sometimes a longer arm on carb helps too.

Well the ECHO engine found a home. It runs good, still breaking in, but it runs and sounds good.

https://www.youtube.com/watch?v=aP4-eHe1FGc This is a video of it in use.

The throttle response is much like a glow engine with the barrel type carb on it.

Interesting plane and a beautiful flying field. Nice work.

Sounds like the engine is running rich though. You don't need to run a gasoline engine four stroke rich for break in. In fact, doing so just causes carbon build up and can actually delay break in. I generally run half a tank of fuel through my gas engines on the test stand; the first couple of minutes in a lean four stroke setting, then I run it peaked, then rich, peaked, then rich several times. I let the engine cool down completely, then I run the rest of the tank through it at a peaked mixture setting, but at various throttle settings but avoiding full throttle for more than 10 or 15 seconds at a time. Then the engine is ready to go in my estimation. I install it on the plane, recheck the carb settings to be peaked and then 1/16 turn back open on the high needle, and go fly it. Don't hover much or do slow airspeed maneuvers for the first few tanks, then run it like you stole it!

AV8TOR