1QwkSport2.5r

I got this engine from a rental yard some years ago. It was originally a String trimmer of some kind, though it couldnt have been a very powerful one. It does still run as-is, but I'm considering converting it to run as a glow. I cant find any info on it through stihl or googling the model number. I measures approximately 16cc or .98 cubic inches. (1.100" bore, 1.027" stroke) so I dont think it would be overkill to run as a glow. Anyone have any insight on this little guy?






edit:
The carb that came on this engine is a Teikei from Japan, the numbers stamped on it are NB and 3L. It also has a primer of sorts. Engine (butterfly) side of the carb is 13.85mm, outer diameter of the carb is 6.47mm approximately. This carb has two mixture needles.

I have a Walbro carb thats bigger, but I dont know if either carb will flow enough fuel to run methanol. The Walbro is a WT 26 and doesnt have twin mixture needles. Engine side is 14.28mm, air cleaner side is 7.9mm.

av8tor1977

My Feedback: (6)

You will find that the power will be low for the weight of that engine. However, it might be good on a floater like a Cub or a Telemaster.

The Walbro WT-499 is made for use with methanol, but at 11 mm venturi it is a touch big for a 16cc engine. You might try a carb from a Ryobi trimmer. They are small, but probably larger than what you have, and they are usually Walbros. If necessary, (and it might be), you can enlarge the passages to double the area in the carb. (Double the area, not the diameter.)

Another option would be to go Gas/Glow, in which case most carbs will flow enough. Look up the "Gas/Glow How To" thread, and read the first two posts for info on that.

Good luck,
AV8TOR

1QwkSport2.5r

If I was going to use it on anything, it would be an airboat if I use it on anything at all besides the test stand. I just know keeping the ignition on it would require keeping the shroud on it which defeats any weight savings possibilities. The crankcase is huge compared to my ST S90, but displacement-wise its real close. I figured this thing should ought to run pretty well anyway.

The walbro WT26 I have came off a 30cc or so string trimmer. The venturi on that is about 1.4mm larger than the Teikei that came on the engine. I'll have to tear it apart and see it can be made to work with methanol. Otherwise I have one more Walbro carb that has two mixture needles on it that is off of something 30cc or larger. I'll have to find it and get the number off of it. Worst case scenario, I have a 30cc homelite that has twin mixture needles I could pirate to try..

I'll go re-read the gas/glow section. I read through the whole thread sometime last summer but I'll refresh my memory some.

av8tor1977

My Feedback: (6)

I wouldn't waste any time on the single needle carb. You definitely need twin adjustment needles for anything that you do with the engine.

Good luck and have fun,
AV8TOR

gr8flyer55

Do you have the airboat already or are you building one for the engine?
Looking for a good size boat myself for a 20cc engine I just converted.

John

1QwkSport2.5r

Turns out the engine the WT 26 carb came off of does have a high speed mixture needle, but the OEM (Ryan/OMC) used a weird recessed needle and put white silicone over it. The engine this carb came off of was made in 1984, so I emissions had nothing to do with it AFAIK. Anyway. it needs a diaphragm anyway so I cant test it until I get a new one.

The engine has twin ball bearings on the crank I found, but I havent checked to see if the conrod has needle bearings or not. I'm assuming it does though.

It won't be easy, but for the heck of it I'll check the port timing on the thing once I get it torn down. Any idea how much the glow plug adapter would cost?

1QwkSport2.5r

I haven't built a hull for this engine. I want to try running it on glow and see how it compares powerwise with my Super Tigre S90K. I think the prop choices are going to be pretty close to the same for this Stihl engine, I just dont know how far is too far on rpm.

If the engine runs good on glow and turns smaller lumber well, I'll build a hull for it. If I built one for this size engine, I'd probably go 36" long and 18-19" wide and maybe 2.5-3" tall. The airboat my SuperTigre is on is 32" x 18" which is a flatbottom balsa/birch construction.

Scota4570

For a hull get a "Boogie Board" from wall mart. There are u-tube videos on this. I have been meaning to make one.

1QwkSport2.5r

Unless they make boogie boards out of wood, I'll stick with my toothpick framework and plywood.

This engine might get converted after all. I think I might build a rescue vessel to recover stalled/flipped boats. Since it would need just enough power to move itself and a little left over to push a dead hull..... I think it might suffice. I need to get the glow plug adapter and I'll just put a new ring in it for the heck of it.