Dean in Milwaukee

I'm converting over a ryobi 26cc 4 stroke, and have found I need to know if I have a long or short shaft for the prop hub.

http://macs-rc.com/ryobi.html
or
http://www.carrprecision.com./Pages/prod02.htm


Problem is, I've got nothing to compare to, so I dunno if I which I need.

Can anybody shed some light on how to tell the difference?


Thanks!
Dean in Milwaukee

gtisme

Dean,

I'm working on the same conversion right now, although I am converting to glow also. Get in touch with Peter Faith at Wacker Engines (http://wackerengines.com) and he can provide what you need. He is very responsive to email and does good work. The hub/prop adapter he made for me fits great and looks great. The shaft on my Ryobi 4 strk is about 3 7/8" from the front bearing to the end of the shaft, is tapered for the flywheel fit, and has threads (for the clutch) about 11/16" back from the end of the shaft. Peter had one of these engines in his shop, so he was able to make the adapter without me having to give him any measurements.

Keep us informed as you go along with this project!

Gary

Dean in Milwaukee

Thank you!


Dean in Milwaukee

ryobi-bob

My Feedback: (1)

Dean

If the shaft from the front bearing to the end of the shaft is around 3 inches or so it is a long shaft.

Usually if they have a clutch they are long shaft, direct drives are usually short shaft.

it is probably a 3/8 - 24 thread also

the prop hub would not be threaded, it would be bored to 3/8 and you would use a prop nut or spinner nut.

www.macs-rc.com we buy some parts from Peter and make some of our own parts.

we machine flywheels, prop hubs, custom prop nuts, engine mounts etc.

Peter is a super fellow.

Bob

Dean in Milwaukee

Sounds like a long shaft then. I emailed wacker engines, got this reply:

"Dean, this engine uses a hub very close the long shaft
hub used on the regular engines, they are $15 plus the
shipping, and come with a prop nut and a machined prop
washer.
Peter"

I had to email him again to find out how much to mail him a check for, but have'nt heard back yet, dunno how much shipping will be, so dunno how much to send.

From what I've been able to determine, this motor dead stock makes about 1.1hp at 7k rpm which should work well with a 16x10 prop, allowing it to actually make it to 7k.

I'm planning on making up a homebuilt foam and coroplast plane, sort of a ultrastick type thing. I've got something built similarly in a trainer style at 72" span and 850 in/sq in electric and its powertrainless weight is only 3lbs. The motor ready to fly will probally be around 5lbs, and I will be making a larger wing at perhaps 1200 in/sq, but I'm fairly certain that I can be flight ready at around 10 lbs. The motor should pull a semi sleek plane at this weight quite well.

gtisme

Dean,

I believe you are on the right track.....1200 or better sq in and 10 to 12 lbs should work out fine. I'm "purdy much" on the same track.... using some of crazyherb's methods to build a stick type test bed for this engine. I like to get all the kinks worked out of the engine before putting it in something that cost a good bit of time and $. By converting to glow I've taken 2 lbs off the overall weight of this engine. I removed the flywheel, stock muffler, front mounting plate, coil and plug wire, spark plug and put them on the scale....2lbs exactly! It will probably be another couple of weeks before I get it on the test stand to tweak and see what it will do. I plan on temporarily running it with the stock ignition, and muffler on gas to get a base line run. As soon as I get the base line, I'll strip it back down and run it on glow and start doing the carb tweaking.

Gary

Dean in Milwaukee

Thats interesting. Are you switching to glow for weight savings alone, or is there another reason?

As for carb work, you may have your work cut out for you. I have some experience with this from my old motorcycle drag racing days.

Couple things to keep in mind with converting to alcohol:

1) fuel compatibility. Methanol can couse problems with the non metal parts of the fuel system. Things can get soft and weak.

2) fuel supply. Generally speaking, going alcohol will double your fuel consumption. On our drag bikes we almost doubled the jet sizes before they began to run right. Hopefully you'll be using a carb with different jets available for it as your going to need them.

3) starting can be tough, especially if its a cool day out. We used to use starting fluid just to get the motor firing.

4) alcohol fuel sucks up moisture from the air at an alarming rate. Absorb enough, and the fuel becomes useless. An airtight fuel container is needed, and never buy more than you'll be able to use in the near future.

On the bright side though, you'll be shedding considerable weight, and you'll also be picking up considerable horsepower. I would'nt be suprised to see you getting 50% more hp on 5% nitro, and maybe much more. You'll probally wind up roughly equal in power to the gas two strokes of the same size.

I do also agree with you about making a cheap test bed before you buy anything expensive to put it in. I personally like cheaper planes better anyway, less worry about crashing such an expensive toy makes for more fun for me.


Dean in Milwaukee

gtisme

Yep, weight saving and more HP. Just trying to get a decent power to weight ratio, besides, I just like tinkering with small engines, especially 4 strokes. On the fuel issue, RCIGN has run racing engines on methanol and says that you can run the non-glow carbs but just have to replace the diaphragm more often than with gas. Replacing the diaphragm once or twice a year is cheap and easy to do. I'm going to work with the stock carb first to see if it will work well, if not I have a box of 2-needle Walbro carbs in the right venturi sizes to work with. The stock carb has a fixed high speed jet with no adjustable needles but they sell the jet for about a dollar, and I have a full set of numbered drill bits to "adjust" it with.

Keep us informed about your conversion experiences and I'll do the same.

Gary

Dean in Milwaukee

Sounds like a plan. I sent out the check for the prop hub last week, so hopefully I'll have it in another week or two so I can begin testing, mostly to figure out prop size.


Dean in Milwaukee