31 cc Ryobi weedeater conversion

31cc Ryobi weedeater on Great Planes Giant Stick. 18x8 Dynathrust prop. 12.7 lbs

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Author Reverseflush ( ago)
Put a cam on it

Author Rejean ( ago)
No plans, it was purchased as an ARF (almost ready to fly) kit. It is a Great Plans Giant Big Stik.

Author Rejean ( ago)
18x8 Dynathrust prop. 7000 to 7300 RPM with 87 Octane 32:1 fuel oil mix. (Your power output will be less if you go with a higher octane fuel) Ryobi crank counter weight is not built of solid stock, therefore it is not recommended to under prop for bench RPM readings exceeding 8000 RPM.

Author dreamwisperer ( ago)

do you have any prop/rpm measurements?
I want to replace my OS 160FX on my Giant SuperSportster ARF with a Ryobi 31cc.

Author Rejean ( ago)
The only data that I can see on the carb is the wording "Zama" in two locations and there is also the number "6" that appears on the edge of one of the covers. The only modification to the carb was to increase the venturi intake to 10 mm and to remove the fine screen mesh filter.

Author Rejean ( ago)
- incl spinner & prop 3.7 lbs, not including CDI module & 4.8V pack for CDI.

- Attaching mounts for ignition coil, etc... were all taken down flush to motors exterior wall body.
- carb 10mm
- Muffler gutted, .6 oz saving
- fin trimming, 2.4 oz saving. Bad idea; mufflers support point no longer in place & thus led to exhaust loosening & once to sheering of an exhaust bolt. Now fly with stock cylinder & everything secure after many flights.

Author Rejean ( ago)
It is a Great Planes ARF kit named Giant Big Stik. specs are: WS 80.5 in / WA 1518 sq in / weight 13-15 lbs / Lenght 54.5 in
I bought it from Great Hobbies a Canadian mail order outfit. I am running mine with an 18x8 Dynathrust prop.

Author Rejean (920 years ago)
When trying to establish the most suitable aircraft for a particular motor size such as a Ryobi (adequate motor but is not on the high end of power) you must go by wing loading. Therefore I would recommend anywhere from 15 to 20 oz per sq ft of wing area. In my particular case, my Giant Big Stiks surface wing area is 10.5 sq ft and the plane weights 12.7 lbs for a wing loading of 19-oz/sq ft.

Proceed to crazyherb on the web and take a look at his design of BigPink for Ryobi motors.

Author junglist1soldier ( ago)
Great work on this Old School plane. Your engine was not as boggy sounding as the first weedeater plane with a ryobi engine,2-stroke. I wonder if all weedeater engines are 2-stroke? I'd think so but, I'm new to this hobby of R/C Planes & I've got myself a 1.20 Biplane, 8 lbs. I wouldn't install a weedeater on it though. I was considering doing this as a side project, & wonder what the maximum weight would have to be, for this to work?
Anyhow, Good Job on this R/C Plane.

Author coshyno ( ago)
how did you convert this engine to be an aircraft engine ???

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