I was thinking of buying a yard machines by MTD 4 cycle gas string trimmer with a 26 cc engine. Does anybody know anything about this engine, manufacture, weight, horsepower?. How much aircraft weight will a 4 stroke 26 cc engine lift? Thanks, Sean

This is a Ryobi made engine. Suitable for Cub like planes in the 1/4 sclae area. I have one of these on the stand now and am tweaking it to go into a Balsa USA Phaeton 90. They do better mounted upright but will run inverted. Mine turns a MA wood 18X6 in the mid 6000 rpm range. The sound is pretty cool too. I got my mount and hub from Carr Precision.

Hi BDTSR,
Could you upload a picture of your engine for us. Here is a picture of mine.

Dave

Dave, I'll take a few pics and upload them in a little while. Your exhaust outlet looks rather small, does it restrict it any?
Brian

Here are two pics of mine on the stand. I do not have a muffler on it as I have been playing with different types to get the sound I want.

Hi Brian,
Thanks for the pictures. I havn't run it yet with this exhust stack. It is about the same size as the port and very short. Is that the stock carb? Mine uses a drum type 9mm carb. I have an 11mm drun carb from a Toro that I want to try. I think that I need to add a spring because of the single pulse of the four cycle.

Dave

No that is not the stock carb. I didn't like the strong tension on the barrel type type carb so I changed it out. I shortend the plunger spring some to allow for the 1/2 pulse from the intake to move the pump diaprham. It's a little rich at idle, but transitions well. I have not tached it with this carb. The old carb gave 6300rpm on a MA 18X6 woody. I may tach it today if I get the chance.

Hi Brian,
That is some good info. I have a ton of small bore Walbros. Thank.

Dave

Hey...just for kicks....see if you get more RPM after cutting down the back-board close to the back of engine. If not more RPM...mabe more pull. Just wondering!!!

Thanks for the info on the engine. How do you think it would do on the new great planes big stick?

Not well. It's kind of heavy and may not balance the plane that well. If you want a cheap gasser, go to Lowes. They have the old style Ryobi in the Bolens trimmer for $70. Throw in a conversion kit and you've got a good running low cost engine.

What is the weight of your 4-stroke?

I was about to put Poulan 25cc in my Wilga, but what I found that this engine that weights 48oz (with magneto) hardly balances the plane. Harbor Freight has Yard Machines trimmer with Ryobi 26cc 4-stroke. I believe it wil have performance close to my Poulan 25cc, but should weight more (and sound better). Any input?

Did everybody die? Or I'm just lucky to be ignored

Additional question I have is: What is the farthest distance from the shaft ?. I wonder if I can hide entide engine in my radial cowl.

No, not ignoring you, just working 60+ hours a week. Haven't touched a plane or engine (so to speak) in 3 months!

I'm sorry. I hope you will have some time soon (for your plane) - the spring is coming. And maybe for the answer too

The weight of mine with mount, hub and prop (no muffler) is 5.0lbs.

Thank you,

Did you measure the distance from the top of the cylinder to the shaft. I need a confirmation if it will hide in my cowl.

Thanks again.

6.25 inches from the top of the plug cap (a little to spare) to the center line of the crankshaft.

I have one of these that I am using as a trimmer, it isn't such a great trimmer and doesn't feed the string well. I think that the next time I hit home depot and see a trimmer on sale I will buy it to use and convert this one. What is the weight on this thing once converted? It looks like it should be lighter than most other 4 strokes, it appears to have allot less extra metal and a much lighter sump. In fact it looks like a possible canditate for my Rascal 110. That would give me 2 planes suitable for 4 stroke gassers and 3 engines. What to build next......

Thanks for the info. I guess that cured my desire

My cowl is 5 inch radius, so the engine will not fit. And I can't cut the cowl - the plane is to nice. So now I'm going back to the original idea of fitting my Wilga with Poulan 25cc converted to glow. Without spark ignition I will be able to get batery and radio whenever I want - even next to the engine

Has anyone found a good replacement carburetor for the stock Walbro WYL, non-adjustable carb?

Hi Richard, The WYK 16-1 works well on the 4 stroke Ryobi. It is 10.5 mm. You will need to relocate the barrel spring to a more relaxed position. Try making a new intake manifold, drilled to 10.5mm,out of 3/8" phenolic. This engine also responds well to intake and exhaust port enlargement , but be carefull, there isn't much metal to work with. A thinner or no base gasket will bump up the compression a little. With an 18/8W APC this little engine pulls almost as hard as a Ryobi 31 cc 2 stroke. Let us know how your coming along.
Mtrhd

Mtrhd, were can you buy this carb.
Thanks Ken

WYK 16-1., $46.51...Look on the Walbro web site for a distributor near you....

Well, I drilled out the main jet to .016" as this was the size that was purportedly perfect for the Ryobi 26cc 4 stroke.
Now, top end is PERFECT. I would say jetting on top is right on.
HOWEVER... now, the engine idles very poorly.

What is strange is that the symptoms are indicative an air leak.
If I cover the carburetor air inlet until about 1/64" opening remains, the engine will idle right down to 1500 rpm or less.

I have disassembled the carburetor repeatedly, looking for any sign of an air leak. I have checked gaskets, intake manifold, everything.

The only thing that was changed was drilling out the main jet and now idle is WAY too lean to run well. The symptom are the exact opposite of what I would have expected since the carburetor runs totally from one jet.

I am about to give up on the stock WYL carburetor, but I have yet to read a single thread that suggests an EXACT replacement carburetor with two needles. Does one exist?