Ryobi 4 stroker, whos flying them and what do ya think.
10-03-2003, 04:39 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Oooooh... i like that but what if the cylinder is only plated? would it ruin the cylinder? He He...a ryboi 31cc piston in there would be cool! We need to look more closely but then again, that kinda work is a bit more than I want to mess with but not out'a the question.
10-03-2003, 05:56 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Tee hee hee!!! And I spent lunch hour thinking of bolting two cylinders to a custom crankcase for a 52cc opposed twin! I've got access to a CNC mill and a manual lathe for chewing out the aluminum. If your buddy could bore 'em out we'd have 60cc four strokes!!!
Is this just a thought exercise, or are we up for some collaboration?!
Is this just a thought exercise, or are we up for some collaboration?!
10-03-2003, 06:12 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
RC,
I also have access to a mill/lathe. In fact, I going over to Joe's tonight to make an alum. rotor hub for my Piccolo. I definetely like the opposed twin layout. Pistons moving in opposite directions and a power stroke on every revolution. This should eliminate the counterweight on the crank and be very smooth. Should sound awesome. Y'd intake runner/1 carb. 2 into 1 exhaust. I'd be willing to sketch out some ideas and mail them to you if you're interested.
I also have 3 friends that are electronics engineers. I am going to ask them to design a electronic ignition similar to the Howell TIM-6 but with advancable timing. Shouldn't be to tough.
Doug
I also have access to a mill/lathe. In fact, I going over to Joe's tonight to make an alum. rotor hub for my Piccolo. I definetely like the opposed twin layout. Pistons moving in opposite directions and a power stroke on every revolution. This should eliminate the counterweight on the crank and be very smooth. Should sound awesome. Y'd intake runner/1 carb. 2 into 1 exhaust. I'd be willing to sketch out some ideas and mail them to you if you're interested.
I also have 3 friends that are electronics engineers. I am going to ask them to design a electronic ignition similar to the Howell TIM-6 but with advancable timing. Shouldn't be to tough.
Doug
10-03-2003, 10:03 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Doug - Yep, that's the layout I was thinking of. A "boxer" might be smoother but has a more complex crankshaft. Alternating has a simple crank, and probably won't shake any worse than the single cylinder does now.
Make that four EE's: I'm one too. Already looking for sources for ignition coils. The microprocessor timing advance is the easy part for me.
Mr. P - Ya got me dead to rights on the simplicity issue! Friends have accused me of grinding rocks to make my on iron ore rather than going to the hardware store to buy a piece of steel. They exaggerate (but I have wondered once or twice...).
Make that four EE's: I'm one too. Already looking for sources for ignition coils. The microprocessor timing advance is the easy part for me.
Mr. P - Ya got me dead to rights on the simplicity issue! Friends have accused me of grinding rocks to make my on iron ore rather than going to the hardware store to buy a piece of steel. They exaggerate (but I have wondered once or twice...).
10-03-2003, 10:49 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Back to carbs at hand. Mine is a Walbro WT-366-1 (Sorry, I mistated the number the other day). The diameter of the throat at the throttle butterfly is 0.437" (11.0mm). It looks like the venturi is somewhat narrower, but I haven't figured out how to get the calipers up in there. Where exactly is the carb measurement taken? At the narrowest point in the venturi?
10-03-2003, 11:51 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
I opened up my second 26cc unit tonite, and found that it contains a Walbro WT-456 carb. The parts list that I found on the Walbro web site sorta cross references the WT-366 to the WT-456, so maybe they're variants of the same theme.
Checking back on old posts, I see that DougT reports that the WT-456 and the aluminum oil pan signify that I have two old first generation engines.
Are there any gottchas about the first generation engines?
Checking back on old posts, I see that DougT reports that the WT-456 and the aluminum oil pan signify that I have two old first generation engines.
Are there any gottchas about the first generation engines?
10-04-2003, 12:45 AM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Here's a link to a magazine article that answers the questions about the three versions of Ryobi 26cc four stroke. http://www.ryobi.com/4cycle/ar_2.html
Trimmer model == Engine
925r/975r/990r == AC1
825r/875r/890 == AC2
1079r/1090r == AC10
Isn't it great what you can find late at night using google?
Trimmer model == Engine
925r/975r/990r == AC1
825r/875r/890 == AC2
1079r/1090r == AC10
Isn't it great what you can find late at night using google?
10-04-2003, 10:25 AM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Cant remember who it was but it was said that a talk with a walbro rep. made it clear that just any carb just wont do on the 4-stroke. Ok...then lets use the return spring in the 4-stroke carb in the other carbs we try. If the pump needs neg. presure and since most parts inside all walbros interchange somewhat we can maybe get lucky and modify any 2-strokes carb with the 4-strokes pump parts. I'll look in a bit when I'm out in the shop. Piper
10-04-2003, 12:53 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
rw,
Thanks for the link. That is the carb I have in the pic. on that link. Mine was from an 825 trimmer.
Piper,
That was me who talked to the Walbro rep. I tried another WYL carb similar to the stock one but a 10.5mm one. I put in a small spring in the diaphram and it ran but was too much carb for the engine. Tried 2-3 different springs. It had a very large jet (46 instead of stock 35) and ran pukey(sp?) rich. Stock carb with a larger jet seems best so far.
Have you noticed that your crankcase has a breather tube/check valve? It vents + case pressure. Could you make your own intake spacer that incorperates this + presure to the input hole on a 2-stroke carb. That way you could use any type of available carb and wouldn't have to fiddle with a return spring.
I'm going to tear my motor apart again this week and see about boring and cam advance/retard. That article mentioned that the cylinder was chrome plated. That shouldn't be a problem as many MX / SB guys have their cylinders replated all the time.
Doug
Thanks for the link. That is the carb I have in the pic. on that link. Mine was from an 825 trimmer.
Piper,
That was me who talked to the Walbro rep. I tried another WYL carb similar to the stock one but a 10.5mm one. I put in a small spring in the diaphram and it ran but was too much carb for the engine. Tried 2-3 different springs. It had a very large jet (46 instead of stock 35) and ran pukey(sp?) rich. Stock carb with a larger jet seems best so far.
Have you noticed that your crankcase has a breather tube/check valve? It vents + case pressure. Could you make your own intake spacer that incorperates this + presure to the input hole on a 2-stroke carb. That way you could use any type of available carb and wouldn't have to fiddle with a return spring.
I'm going to tear my motor apart again this week and see about boring and cam advance/retard. That article mentioned that the cylinder was chrome plated. That shouldn't be a problem as many MX / SB guys have their cylinders replated all the time.
Doug
10-04-2003, 01:55 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
my engine is a 990r model and the vent is in the valve cover, but like you, I've been trying to think of a way to use crankcase pressure to pump the carb and yet allow the normal venting. I think swaping pump parts from carb to carb untill we find a carb it likes may be the less troublesome way.
oh wait...you have a newer model than mine so you might be able to do something like that with your vent tube. You do know where to drill and tap on the carb to put a nipple to attach the vacum line to right? If not I'll post a pic of one of my carbs for ya.
oh wait...you have a newer model than mine so you might be able to do something like that with your vent tube. You do know where to drill and tap on the carb to put a nipple to attach the vacum line to right? If not I'll post a pic of one of my carbs for ya.
10-06-2003, 12:18 AM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Mr. P,
I was going to put a "T" in the vent line with one of the lines to the current check valve and the other line to the carb for pressure pulses. I tried swapping the stock spring but the stock carb has been milled for the conical shaped spring. Haven't tried on any type of butterfly carb yet.
rcwilder,
About the ignition. How hard do you think it would be to figure out a circuit that could take 5-6v up to spark voltage 15K+? Also, about changing the timing. I've read somewhere else that a curcuit can't predict when a circuit will be tripped(hall sensor/magnet) but can delay a trip. You could have the hall sensor trip the full advance timing and the circuit would delay the spark incrementally at lower rpm's. You could also have two magnets. One for advance and the other for idle. What do you think? Cost? Complexity? Parts availability?
About the ignition coils. Model Electrics makes them. I don't know their website, if any, but go to jerry-howell.com and he sells them. The ones I bought from him are $27.50 shipped.
I also thought about the boxer twin. Siamesed cylinders. About the only thing we would have to do is make a custom crankcase and either modify a crankshaft or make one. Last night I spent a few hours on a lathe/mill and had a ball. I'm still learning the intricacies of it but my project turned out well. Your access to a CNC would be the cat's meow.
A motorcycle buddy told me tonight that there are companies out there that have pre-cast piston blanks. You tell them your bore diameter, wrist pin diameter, ring info, and crown height and they finish mill it. He said prices are reasonable.
I was going to put a "T" in the vent line with one of the lines to the current check valve and the other line to the carb for pressure pulses. I tried swapping the stock spring but the stock carb has been milled for the conical shaped spring. Haven't tried on any type of butterfly carb yet.
rcwilder,
About the ignition. How hard do you think it would be to figure out a circuit that could take 5-6v up to spark voltage 15K+? Also, about changing the timing. I've read somewhere else that a curcuit can't predict when a circuit will be tripped(hall sensor/magnet) but can delay a trip. You could have the hall sensor trip the full advance timing and the circuit would delay the spark incrementally at lower rpm's. You could also have two magnets. One for advance and the other for idle. What do you think? Cost? Complexity? Parts availability?
About the ignition coils. Model Electrics makes them. I don't know their website, if any, but go to jerry-howell.com and he sells them. The ones I bought from him are $27.50 shipped.
I also thought about the boxer twin. Siamesed cylinders. About the only thing we would have to do is make a custom crankcase and either modify a crankshaft or make one. Last night I spent a few hours on a lathe/mill and had a ball. I'm still learning the intricacies of it but my project turned out well. Your access to a CNC would be the cat's meow.
A motorcycle buddy told me tonight that there are companies out there that have pre-cast piston blanks. You tell them your bore diameter, wrist pin diameter, ring info, and crown height and they finish mill it. He said prices are reasonable.
10-12-2003, 08:52 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Doug -
I've been following another thread titled "Scratch Built Ignitions" that addresses your questions. The Modelectric coil is said to be inappropriate for CDI ignition (but great for Kettering). A microprocessor chip can be used to automatically advance the timing proportionately to speed. Also, two hall sensors can be used for a simpler two state starting vs. running advance).
I've been following another thread titled "Scratch Built Ignitions" that addresses your questions. The Modelectric coil is said to be inappropriate for CDI ignition (but great for Kettering). A microprocessor chip can be used to automatically advance the timing proportionately to speed. Also, two hall sensors can be used for a simpler two state starting vs. running advance).
11-30-2003, 03:22 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Mr. P.cub,
I ran my Nosen Champ(108"?) and Ryobi yesterday mounted upright. APC 18-8Wide, CH ignition, stock plastic barrel carb, bored out jet and got 5600 rpm. I then took the throttle barrel assy out and rotated it 180' and gained another 100 rpm to 5700. ???? That is with the timing at 30' btdc and idle at about 0'. Idle was as low as 1100 but liked 1300-1400 better. Just out of curiosity I turned the whole carb assy over so the pump bulb was on top and lost 1000 rpm then switched it back.
Flew very well but I didn't use locktite on the head/mount bolts and they came loose/out during flight and leaked oil everywhere and died on aproach. I cut a new gasked and locktited the bolts and mounted the engine inverted and turned the carb over so the throttle wheel was again on top. 8" breather tube running to top of firewall above oil pan. It ran OK, only 5300-5400 rpm and the idle was very surgy and would often die. Also, oil was occasionally spurting out of the breather checkvalve. This made a mess of the front of my plane. Tonight I will turn the engine back upright. It seems to be much happier.
Bud Nosen Aronca Champ, 108" span, boat load of wing area, 14#, 55' takeoff roll. With the engine back upright and the 5700 rpm, it should shorten the takeoff noticeably.
Doug
I ran my Nosen Champ(108"?) and Ryobi yesterday mounted upright. APC 18-8Wide, CH ignition, stock plastic barrel carb, bored out jet and got 5600 rpm. I then took the throttle barrel assy out and rotated it 180' and gained another 100 rpm to 5700. ???? That is with the timing at 30' btdc and idle at about 0'. Idle was as low as 1100 but liked 1300-1400 better. Just out of curiosity I turned the whole carb assy over so the pump bulb was on top and lost 1000 rpm then switched it back.
Flew very well but I didn't use locktite on the head/mount bolts and they came loose/out during flight and leaked oil everywhere and died on aproach. I cut a new gasked and locktited the bolts and mounted the engine inverted and turned the carb over so the throttle wheel was again on top. 8" breather tube running to top of firewall above oil pan. It ran OK, only 5300-5400 rpm and the idle was very surgy and would often die. Also, oil was occasionally spurting out of the breather checkvalve. This made a mess of the front of my plane. Tonight I will turn the engine back upright. It seems to be much happier.
Bud Nosen Aronca Champ, 108" span, boat load of wing area, 14#, 55' takeoff roll. With the engine back upright and the 5700 rpm, it should shorten the takeoff noticeably.
Doug
11-30-2003, 06:55 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Great to hear you got it flying Doug! I 'm going to put an ignition unit on mine too. Got one off ebay for $13 said to be in new condition, hope so. Can you post a few pics of your setup so can have a head start on mine? I'm going to start off with everything else stock same as you and get a baseline before I start tinkering too much. You know, If you want to get by the inverted problem with the check valve you could remove it from the valve cover and put it in the crankcase\oil pan. But i'll bet the bottom of the piston isn't liking to be submerged in all that oil when up-side down anyway. Piper
02-16-2004, 04:17 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
I finally got a pic of the 4-stroke muffler.
The internals are very similar to this muffler I'm building now.
The internals are very similar to this muffler I'm building now.
05-31-2004, 08:09 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
I just saw a Ryobi weed whip on sale a Meijers....$149 complete!!! May be found for less...I bet. Any new RC,ers have more data to add??? Thanks Capt,n
06-09-2004, 10:11 PM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
Harbor Freight item # 54082, this is the 825r..........AC-2 consumer model. I think I'm goin' to have to bite on this one at $79! They have the PDF manual on their site too.
Gary
Gary
02-17-2005, 10:52 AM
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RE: Ryobi 4 stroker, whos flying them and what do ya think.
I just got one of the harbor freight 825's, was $88 shipped!
I am quite new to this conversion business, but was wondering why people don't use the stock ignition system. Is it the weight issue? On the surface it would seem nice tio not have to carry/worry about an ignition battery.
Dean in Milwaukee
I am quite new to this conversion business, but was wondering why people don't use the stock ignition system. Is it the weight issue? On the surface it would seem nice tio not have to carry/worry about an ignition battery.
Dean in Milwaukee
