combatpilot

Damn I cant remeber when I have seen that much snow. BRRRR. I dont want to rub it in but it was 65 and sunny today here. kind of humid though.

I finally got my test stand built today and did test #9. more to come I just dont have time to post at the moment.

diceco

AMAZING YOU START YOUR MAGNETO EQUIPPED RYOBI BY HAND!!!!! I was never able to do that, not even close, which is part of the reason I went for the electronic ignition!

The motor doesn't sound like it's "two cycling" to me. If it is "two cycling" it must be the muffler or lack of it that sounds so different from mine. Have you leaned it out at all to see what it does? I would think with over three hours of run time on it the ring would be broken in and you could start to lean it out. Do you have an idea of what the carb jet needles are set at?

diceco

av8tor1977

My Feedback: (6)

If I remember right, there are two different magneto systems offered on the Ryobis. One of them is "hotter" than the other, and if things are set up just right and your technique is good, they will hand start.

AV8TOR

combatpilot

I am thinking there is more than one as I have found two different units and neither will hand start. you phisically cannot spin it fast enough by hand to get an spark at all even without the plug in. the only way mine get spark is by using a starter and getting the speed up. below a certian point it just will not spark.

Anyhow I got my ignition in the mail today. man i was glad to finally get a look at it. it looks great for the money. I cant wait to get it on there.

ok again I did finish my static thrust test stand. and here it is.





As you can see the mount I made lays the engine on its side. this works great as now the carb screws are very accesable. with the engine in this position I can take tach readings on the bottom side of the engine opposite of the mag. This works great as now my tach is rock steady and free from the mag interferance. I made the engine mount socket into the attach point so all I have to do is take one pin out and remove the engen so it can be worked on on e the bench. Also with this mount the carb is very accesable and can redible be removed or worked on without having to remove the engine. There is a plastic block set up to where the top block slides over the other block. When the fuel line is placed on the lower block and the upper block slid over the line it acts as a nice fuel valve so the engine can be removed without making a mess.

After running my engine a while it seemed i could not get a good reading from my new scale. After looking at it I discovered that from the vibrations the roller balls were working their way into the aluminum rails and rendering the whole thing useless. So what I thought was a great deal on what I though was killer drawer slides turned out to be not so good. I need to find a better pair of slides and rework my test stand. I hope I can salvage it as it was lots of work.

To make matters worse I droped my stupid tach and now it will only read the 3 blade props and will not set itself for a two blade prop. I dont know if I can fix it and even if I did I dont know if it can be trusted again. I just dont have the money to get one of them better tachs or a new one.

I am getting kind of frustrated as I dont seem to be making much progress on my testing. I have had so many problems along the way I dont know how accurate my information is. I think this whole process has been a learning process to get to a point to be able to do another more accure test process again for a second time. After I finish the last 3 tests I am going to put this engine on my plane and go flying lol. I am planning on starting a whole new thread and start this whole process all over again now that I will have my process down.

combatpilot

Hey what do you guys think of this I think im gona order one.

http://cgi.ebay.com/Digital-Laser-Ph...3A1%7C294%3A50

Andrew66 it looks like form your video that you have the small case engine with the recessed reed backplate is this so?

Flathead

My Feedback: (11)

Hey combat, I was wondering if that thing was going to fly, just joking. Those of you that hve been looking for a TACH, I have and old
"at least 15 years" HOBICO that a guy gave me because it didn't work. I traced it out, and put new batteries in it, and it has been working great ever since as long as I remember to turn the switch off. it has been dropped, hauled to many flying trips, and just keeps on working. I suppose they are still available, will try and check it out. Back to basic's, I am healing up and getting around again. Nice today, so I rigged up two RYBOI's, charged some batteries, set the timming and started recording additional information. Don't have anything jotted down yet, but will try ang get some spec's tommorow. I am starting from scractch, because I was out of action and didn't get everything written down. Will try and get better info this time around. Flathead

combatpilot

Glad to see you back up and around flathead. Yea everyone here is starting to ask if its ever gona fly to lol. I think we all need to agree on a standard test prop so we all get numbers from the same prop combo. I think the dynathrust would make a good one as it is pretty cheap. just a little over 10 bucks as i remember for an 18-8.

Racinrc14

My Feedback: (7)

Hey Combat, yeah the Postal Anus tried to deliver my ignition on Monday, but no one was home (imagine that, nobody was home around 2:30PM, maybe because we have to WORK?!?!) and they didn't leave the little yellow note saying they tried to deliver it. I didn't even know they tried to deliver it until I looked up the tracking info. last night. Man, I hate our postal system. Anyway, I'll be picking it up today. Did it come with any instructions? I can't wait to see the difference it makes on your motor.

andrew66

Its a pretty drawn out proceedure. I plug the carb with my finger and flip 3-6 times. then with throttle open (mags off) i flip it quite a few times, and then with throttle closed (mags on) i give it a good flip. I have the older coil on my engine so it could be hotter. I also found that "slapping" the prop doesnt work as well as flipping the prop and flicking my wrist just before TDC. Or maybe i just got lucky.
I know it sounds like its not 2 cycling, and most of that has to do with the muffler. When the muffler was stock, it would sound like a 2 stroke, but for some reason when i opened up the muffler, it changed the sound. Im going to have to braze some pipes in the muffler when i get a chance, and also when it starts to warm up more, i might run it again.

diceco

Hey combat, Nice looking stand! I sure like the idea of having a "cartridge" that allows a quick removal of the engine. It's a bit of a chore the way mine is set up. Sorry to hear your tracks are notched already! Can you re-adjust the position of the drawer so the rollers contact a different place on the track?

A couple of comments if that's ok.

Be sure your fish scale is pulling exactly in line with your drawer tracks or you won't get an accurate thrust reading otherwise. It will read higher than true because of the vector/force/angle thang.

I too have my motor mounted sideways but IN THE OPPOSITE DIRECTION! If I had it mounted so that the carb needles faced up in the direction you have yours mounted the crankcase port to the carb would be blocked! Do you have a carb adapter plate that ports the crank case around to the other side of the manifold?? Or a Walbro carb with jets on the opposite side than mine??

On your tach problem. I think you said you had a GloBee. On mine you can "save" the default propeller configuration by holding the "save" button down until the propeller graphic starts blinking after which you release the button and wait for it to stop blinking. Use the same procedure to return to the normal operation of being able to cycle through the prop configuration choices. I hope that works for you.

Your standard calibration prop is a good idea. I'd be willing to spend $10 on it. You proposed the DynaThrust 18x8. Where did you get yours?

diceco

combatpilot

I could re adjust the position of the track but it only last a few minutes then its back to inacurate readings.

not that I know of. its the standard walbro carb far as i know. all that i have seen the needles face away from the muffler when mounted.

it scrolls through all the prop settings but it only goes through the three blade props. I dont know maybee i do have it in a wrong menu i just dont understand it. I got it tore apart right now and my positive wire was barely attached to the printed circuit bored. I stripped it and held it back on the pin and it worked like it should now but i havent had time to solder it and put it back together yet. I ordered that laser tach from ebay last night. It was just under 18 bucks all total. hope its a good one and i should be able to check my glowbee against it.

I think I got my prop from tower hobbies. It dosent look like they sell that brand prop anymore. I dont know where to get one. they have the master airscrew for about 15 bucks but man i hate to buy a new prop. any ideas?


no no instructions or any literature at all. I wonder if there is any on the website. If you find some let me know.

Tommorow I should get a chance to try and find some new drawer slides. Looks like grizzly has a good selection and fortunatly i dont live to far from them.

diceco

8500 rpm! That's a pretty impressive number even with an 18x6 prop. What Ryobi version do you have and what mods have you done to it to get that sort of performance? What brand of prop are you using? I assume the prop is not modified from stock!

diceco

Racinrc14

My Feedback: (7)

Looks like Happy Hobby in Milwaukee has a few Dynathrust 18-8's left. Their number is 414-461-6013.

combatpilot

How much is happy hobbie asking for them? we need to find an affordable test standard. I hate to use an APC prop for testing as I think they dont load the engine as other props do. thats kind of why we need a test standard.

av8tor1977

My Feedback: (6)

On mine, the prop is a Zinger 18 x 6. Mods are:

CDI ignition set at 28 degrees.
Aftermarket two tube muffler.
11mm venturi carb.
Standard cylinder with exhaust bridge and no "slits"
Frank Bowman ring. (piston ring retaining pin modified) .000" ring gap.
Base gasket left out; deck height .030"
Exhaust port timing raised to 150 degrees.
Reed stop set to .125" (1/8 inch)

I too was a bit surprised at how well it runs. An honest 8500 rpms with a TNC tach.

AV8TOR

P.S. This is with what I call the "good" reed valve that is not recessed in the backplate.

diceco

As of today at 14:25 eastern daylight, Happy Hobby has no 18x8 Dynathrust props. The least expensive 18x8 props at Tower is either a Top Flight wood or Master Airscrew Classic nylon both at $15. They are "parts express eligible" so shipping is $5. Still that's $20 just so we all can be on the same page. I have a MA 18x8 Classic on hand so it would be painless for me if you all decided that would be a good "standard" test prop!

diceco

diceco

How do you folks measure exhaust timing, specifically how do you determine when the exhaust port opens? Do you consider it's open when the top of the ring (for one ring pistons, or the top of the top ring for two ring pistons) just clears the top of the exhaust port on the piston's way down, or do you use the top of the piston as that point?

Has any one measured the performance effect of increasing the duration of the exhaust cycle? I get the idea that a typical stock Ryobi has about 120 deg of exhaust duration so bringing it up to 150 is a significant change, yes?

Has anyone played with transfer port timing?

diceco

Flathead

My Feedback: (11)

I have a TOP-FLIGHT Wood 18 X 6-10 prop that I will be using. That should give me good close results to compare with the rest of your. Now all I need to do is get going. I am over the infection, but I am having trouble getting my energy back, and it is back to cold and windy which dosn't help. Went out back of my shop, and sombody had left me three JOHN DEERE weed whips. Haven't had time to look them over much, but I think they are about 24 to 26 cc. More fun. Flathead 4

combatpilot

Man i dont know what to do on the props. TO bad tower dosent have the dynathrust anymore.

I did change the timming on mine to 150 degrees. I havent had a chance to test it yet as all my test equipment seems to be failing on me.

I used the degree wheel set up i had and stuck a light in the spark plug hole and rotated till i could just see light from the exshaust port. this way your looking across the top of the piston and should get a more acurate reading. record tihis number. then keep rotating till the light just goes away again looking across the top of the piston from the exhaust port. record this number. the difference of the two is the degrees of travel that the tranfer ports are open ie 120 or 150 degrees.

Racinrc14

My Feedback: (7)

If I may, I would suggest using the MA 18-8 classic if the Dynathrust proves too difficult to obtain, primarily because of it's color. The black prop provides high contrast to light backgrounds so our photo-tachs will work better than they might with the lighter color wood props.

diceco

Good point on the prop color. As mentioned earlier the MA 18x8 Classic would be great for me as I have one.

I would like to get concurrence on the prop choice (and agreement to acquire the prop??!!) from av8tor1977 because he seems to have the strongest motor of those participating in this thread. It seems like his motor is the target at this point, unless the Zinger 18x6 prop is terribly inaccurate in their pitch numbers.

My measurements show the difference between 18x8 and 18x6 using APC props is about 500 rpm, so if av8tor went up to an 18x8 his Ryobi would still be turning close to 8000 rpm!! That would be amazing as far as I'm concerned and I'd sure be trying to duplicate his configuration and mods.

diceco

diceco

Got my 12.7mm Walbro in the mail today. That venturi is HUGE. I hope it works, ie it's not too big. I noticed that av8tor is using an 11.1mm carb.

I should be able to run it up tomorrow.

diceco

madman75

I've got a Ryobi 31cc I modified late last year. I put a Walbro WT-324 carb on it because it had a 7.54 mm stock carb. I have a homemade aluminum plate for the mount. All I need to do is have my brother turn some standoffs for me. I put EI on mine. I got a prop adapter from CH Ignitions and a free EI from a friend. The ignition is an S/S ignition in the round can. Anyway, I ran it with a Zinger Pro 16X8 and got around 7200 rpm with it. I did modify the muffler that came with it. I removed the tube from inside the muffler and removed the little exhaust deflector. I drilled a 3/8" hole inside the muffler at the muffler inlet. I wanted to open the muffler as much as I can. I welded a 1/2" ID x 5/8" OD 3" long outlet tube. It ran pretty sweet the last time I ran it. I want to try it with a Zinger 18X6 prop and see how it runs and check the rpm's. I may run it this weekend and post some numbers.
I haven't done any other mods to it. How do you guys open the exhaust to get the timing to 150 deg? Use some kind of grinding wheel and or sanding wheel? Some more info. on this would be appreciated.

av8tor1977

My Feedback: (6)

My problem is two fold... I live in Mexico and it is a bit tough to find props here. (ha ha). The other problem is that only that Zinger 18 x 6 will fit in the smallish spinner cone of my big Tiger Moth. Any larger prop just won't fit. I normally use APC props, but an APC 18 x 6 won't even begin to fit my setup.

Some time ago, I read about someone getting 8000 plus numbers on their Ryobi with similar sized props, and I didn't particularly want to believe it until I built this one for myself.

Hey, I lied. The prop is a Top Flite. I was thinking it was a Zinger until I searched out this pic to post.....

AV8TOR

combatpilot

I guess the Master airscrew is gona have to be the test prop. thats to bad as i have three of the dynathrusts lol. I really hate to have to buy one now as im broke as can be. It may be a while till I can do so, so im gona keep testing with my dynathrust. Its pretty close to the master airscrew anyhow.

As far as working the ports I use a dremmel tool with a small carbide cutting bit. Go slow and be sure to cut evenly across the entire port so you dont get a uneven shaped or lopsided port. I highly recomend practicing on a junk cylinder first.

Dieco I got the 12.7 carb also. It works just fine really. I am betteing there wouldnt be a noticable difference between this carb and a 11.11 mm i plan on checking this out sometime though when i get some money again..

I got sidetracked on my engine stand build today. I had a friend call me and told me there was a shop that had a whole pile of weedeaters and blowers out back and they were free for the taking. You can bet I hauled ***** over there and loaded up. Man what a gold mine. all in all i think i made out with about 23 engines. I got 4 or five ryobis, a but load of the poulan 25 cc engines, 3-4 of the craftsman 32 cc wich look just like the poulan just more cc. A 45 cc chainsaw motor of unknown manufacturer. polan would be my guess. I ryobi engine I have never seen before and it looks like the poulan cylinder with a different crankcase, 2 poulan 25 cc four stroke and man was I happy to find these. I dont know why but the four strokes really intrigue me. and a few odd ball engines that could be interesting.

I spent the better part of the day stripping them all down to the bare engines and getting rid of all the crap i didnt want. it still fills my wheelbarrow with what is left lol.