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  1. #76
    ckangaroo70's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


    ORIGINAL: Racinrc14

    CKangaroo, where's London Mills? Darn Illinois weather, you're right though. It's either so hot you get the glunk, or so cold it's hard to move your fingers.
    Well we are inbetween thousands of acres of corn to our North, South and West, and then a few thousand acres of beans to our east!LOL Actually I am not to far from you. London Mills is about 30 miles straight west of Peoria and sits right on the Spoon River. We are the home of the Spoon River Scenic drive if you have been on that. Our Club is located in Maquon, Illnois which also sits on the Spoon River, and our flying field sits on a hill and overlooks the river valley. Hence our clubs name is Spoon River Flyers.

    A fellow club member and friend is the one who made my Ryobi conversion parts for me. He turned my prop hub for me, and also took the fins down on the flywheel. I also figured out later that my throttle arm was not going to open all the way with the mount I built...so I also had him make me a spacer to shim out the carb a little which I have yet to install. I am not sure how much it will hurt or help performence, but it must be a fairly common issue as I see www.wackerengines.com also sell a spacer for the carb.

  2. #77
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Dieco I dont have one of the cylinders with the slots cut in from the exshaust port to the transfer port. I havent even seen one of these so i cant to a comparison on this type. Do you have any pics of this I would like to see it.

    I agree with you on the older style engine witht he single runner intake transfer ports. This engine or on mine at least has a much higher compression head than the newer one with the two ports per side. unfortunatly like you say the older engine has the single ring piston which is pretty lousy. In my opinion so far the best set up is to find the older engine and then get the new style two ring piston to put in it.

    I didnt get the magnets yet as I havent had a chance to get into town. I checked on my order status yesterday and it says its all on hold till they get the 8 servo extension wires i ordered to. man i hope that dosent take to long. I want my stuff lol.

    I am going to try and find some thinner shim stock today and experiment with the reed vave set up.

  3. #78
    av8tor1977's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Hey ckangaroo70, I can't get the link to your website to work. Is it broken, or the website down?

    Thanks,
    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  4. #79
    diceco's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Ok, sorry for the way too complicated explanation of correcting data. It's not too hard really.

    1) Measure RPM and air temperature.
    2) Add 460 to the air temp.
    3) Divide that result by 519
    4) Take the square root of that result. That number should be between .96 and 1.04
    5) Take the measured RPM and divide it by the number you got in 4)

    That's the corrected RPM.

    Now you can compare data taken at different air temperatures.

    diceco

  5. #80
    XTOL's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


    ORIGINAL: av8tor1977

    Hey ckangaroo70, I can't get the link to your website to work. Is it broken, or the website down?

    Thanks,
    AV8TOR
    If you are talking about this link:

    http://www.tesla-2.dyndns.org/~mhammer/us60/

    then that is my web page. ckangaroo70 has it in his sig.
    We are both in the same club.

    The page is up and working. Its using dyndns.org for domain
    resolution and they are sometimes a bit flaky.

    Mike Hammer
    Moved to Iowa...goodbye to Illinois...

  6. #81
    av8tor1977's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Hmmm, clicked on it and it still wouldn't open. Could it be because I am in Mexico? Don't have problems with any other sites, links, etc.

    Av8tor
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  7. #82
    XTOL's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


    ORIGINAL: av8tor1977

    Hmmm, clicked on it and it still wouldn't open. Could it be because I am in Mexico? Don't have problems with any other sites, links, etc.

    Av8tor
    Location should not matter. What exactly do you see if anything?
    What error message if any?

    I run a number of sites on that server and have had no reports
    of any problems.

    Try clearing the cache on your browser. That often clears up
    problems like this.

    PM me so we arent hijacking the thread.

    Mike Hammer
    Moved to Iowa...goodbye to Illinois...

  8. #83

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Combat, mine has the older jug and piston also. I would like a two-ring setup, but ordering parts for this seems like a crapshoot. I've ordered the carb rebuild kit 3 times and have got three slightly different variations of the same kit. They work, but each kit has different extra pieces in it. I'm not sure if I order a piston assembly that I will get what I want. I'm using the 720r parts schematic. Perhaps there is a different one for the newer pieces?
    Tommy Dale
    Racinrc14@yahoo.com

  9. #84
    ckangaroo70's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Combat

    Is there any way to tell a single ring from a double ring engine without tearing the engine apart or muffler off? Like perhaps something in a serial # or model # or something? The reason is... I hit a few yard sales and auctions in the summer time, and it would be nice to know if a guy knew what he was looking at and whether a string trimmer has a one ring or two? Perhaps a change over date?

  10. #85

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Partial quote:

    "unfortunately like you say the older engine has the single ring piston which is pretty lousy. In my opinion so far the best set up is to find the older engine and then get the new style two ring piston to put in it."


    To be fair to this lowly design:

    (1) What did the end gap of this piston ring measure?
    ( 2) Was the ring face and sides free of any nicks,or scratches?
    ( 3) Condition of the bore it was asked to run in?
    (4) Did you check the ring on a surface plate ? (Glass plate with a new piece of ~ 1000 grit oiled wet/dry)
    (5) What was the piston ring groove to ring clearance?
    (6) Is the piston groove completely contamination free?(no burs,nicks,or contamination)

    Some folks call this "blue printing", measuring all the basic stuff, before messing with the mods.

    Just an old mechanic wondering....

    It would seem unfair to dismiss a design that has proven very effective in minimizing friction in countless high performance applications,due to missed concepts,with such a blanket statement.
    Information on the Internet is subject to the same rules and regulations as conversation at the corner Pub -Author unknown.

  11. #86
    ckangaroo70's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


    ORIGINAL: av8tor1977

    Hmmm, clicked on it and it still wouldn't open. Could it be because I am in Mexico? Don't have problems with any other sites, links, etc.

    Av8tor
    It works fine for me as well. Not sure what the problem might be. Its a shame you can't view it because it really is an excellent source if a person is interested in building an UltraSport 60. That site belongs to RCU member XTOL, and he is the one who built the Plane. I just keep it in my sig line because it really is an excellent resource.

  12. #87

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    This is what I get...

    The page cannot be displayed
    There is a problem with the page you are trying to reach and it cannot be displayed.



    Please try the following:

    Click the Refresh button, or try again later.

    Open the Web site home page, and then look for links to the information you want.
    If you typed the page address in the Address bar, make sure that it is spelled correctly.

    Verify that the Internet access policy on your network allows you to view this this page.
    If you believe you should be able to view this directory or page, please contact the Web site administrator by using the e-mail address or phone number listed on the Web site home page.
    HTTP 502 Proxy Error - The Uniform Resource Locator (URL) does not use a recognized protocol. Either the protocol is not supported or the request was not typed correctly. Confirm that a valid protocol is in use (for example, HTTP for a Web request). (12006)
    Internet Security and Acceleration Server

    Tommy Dale
    Racinrc14@yahoo.com

  13. #88
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    I understand the pain of getting parts. Worst part is if you go to a repair shop i think the parts guys cant even go to the bathroom without a serial number. Sounds like we need to start a data base and when you tear one down that ya got cheap we can list the serial number and what parts it has so we can go order parts and have a serial number for the parts dummies at the store lol. I would do that with mine but that info is long gone Dohh.

  14. #89
    ckangaroo70's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    I went out and found my plastic junk that I tore off my Ryobi. My Ryobi came off a string trimmer. Engine Family is YN4XS.0314RA; EM

    I also believe it is a 725r model.

    So folks can check theres against mine...mine is a 31cc with a Zama carb, and a single ring. About the only thing I can gather from the engine family number is the .031 which I assume stands for 31cc. Perhaps there is a website somewhere that explains these numbers, but as of right now I have not seen it. So I think it would be helpful if some other folks chime in with engine family numbers.

  15. #90
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Yea we really need some numbers of engines that have the two ring set ups. I dont know if there is a way to tell if it has a single or a double ring engine other than tear it apart. if it is old enough i imagine you can bet its a single ring engine. I am not sure at which point they introduced the double ring.


    Ok so I had a chance to work on this again today. I got some very interesting information today.

    Heres what I started with. I fabricated a way to find tdc. Basically what I did was take a spark plug and knock out the ceramic. I them bored it out to fit the stub on the end of my cheap but yet works very well harbor frieght dial indicator. I drilled and tapped some holes to put set screws in to hold it all together. It is then screwed into the plug hole on the cylinder head. I then fabricated a degree wheel and pointer. I had a buddy of mine cad it up and i hand drew the numbers. I glued it to a piece of plywood and then sanded it to shape. I then applied a few coats of polyurathane to help protect it.

    Ok so you turn the flywheel till the dial indicator stops. note this number. then keep turning. the flywheel will turn a few degrees till the needle starts to move again. when the needle moves again note this number. if you move the flywheel to halfway between these two numbers and then set the degree wheel to TDC 0 degrees then this will be the exact TDC. now you can check port timming.





    Ok so once my tdc was established here is what i found for port timming

    Exhaust opens at 110 deg and closes at 250 deg for a total of 140 deg exhaust port timming

    Intake opens at 115 deg and closes at 245 deg for a total of 130 deg of intake timming.

    Ok so after finding my port timming I then marked on the bearing housing and flywheel the TDC and 10, 20. 30 deg marks before and after TDC



    So when performing my tests today i also got to see what the timming of the stock ignition is. this si where it gets kind of interesting as the stock ignition is a little more complex than I had thought. I did also confirm that the flywheel and the coil is a macthed set from manufactrere and there is no interghanging them if the crank has different keyway location. When I used the new coil with the old flywheel it was so far advanced I could not read it. If I had to guess I would have to say it was around 50 deg BTC.

    When running the engine and using my timming light i found that it had about 20 degrees advance in it at a low rpm. I was increasing the rpm to see if it had a advance curve in it and at one point in the rpm range it changed to 29 deg BTDC. If you throttled it up at a certian point it would shift from 20 to 29 degree advance and back again as throttle was reduced. It was a very pronunced change when it happens. kind of like flipping a switch to a different setting and not like a curve at all. So again I now know what the timming of the ignition is and i now know these stock coils have a little more in them for electronics than i had first thought. I dont think it would do me any good to change the crank and coil setup to the new one to see what it is. I am betting it will be 20-29 degrees or something very close. I know the newer crank is timming retarded on the keyway but so is the coil electronically as I have now proven.

    Ok so with all this information I now went to test #7. this is a three part test of the reed vavle.

    First test is to use the stock valve with the engine set up just like test 6 to get a baseline rpm for the day.

    the first rpm baseline is 7050. 120 rpm less than the last time I tested but it gives us a baseline for today.

    The next part of this test is to modify the reed valve by narrowing it by the attatching end. I read about doing this I think on one of crazy herbs sites. its the one in the middle and the one on the left is stock.



    Ok when all put together and runn here is what I got

    RPM 7410 for a net gain of 360 RPM !!!!!!!

    Wow I have got to say I was sure supprised at this improvement. still 240 RPM better than the testing of the other day.

    Ok so now i was thinking it would be nice to try cutting a reed out of a thinner shim stock. the stock valve is .006 and while looking at my feeler gauges a .003 valve would really work good in my opinion. I looked for some shim stock and all I could find was a grainger and they sell it in such a quantity that it is not cost affective to me. I need a small bit and they have it in rolls. i think the smallest is 6 inches by 50 inches. its about 14 bucks which is not to bad but i hate to spend that much for a small test. If anyone knows where I can get a small quantity for cheap please let me know.

    I was looking at a roll of thin rubber i had in the shop and got to thinking if it would work as a reed valve. I cut one out and tested it to gas. I dont think it is gass proof but it should work long enough for a test. It is the one on the right in the picture. Ok so i installed it in the engine and tried it out. when i tried to start it it would run just a little bit then stop. i could never get it to run. I had figured ok its just to soft and would not work and was about to give up for the day. I decided to go ahead and pull it apart so it would not disentegrate into the engine from the gass and this is what I found.



    What I didnt realize is with the rubber when tightening down the reed stopper the end would ip out farthur that with the metal reed valve. What had happened here is the crank hit the reed stopper and turned the whole thing sideways wiping out the locator pins. I put it all back together and used some small screwws to replace the pins and keep it all in place. I then reset the reed stopper and then reassembed the whole thing and ran it.

    Rubber reed RPM 7410.

    Ok so now the RPM did not improve on this test. I have two thoughts on this. Either i have reached the volumetric efficency end of this set up with the rubber and modified metal valve or the ignition has a rpm limmiter as i had read somewhere else on another post. This is very possible as the RPM was the same. I will have to get my new ignition installed to be able to know this. Again it may bee that the modified reed is as good as it get with the port sizes or the ports just cant possible flow anymore.

    With both of the modified reed valves the idle was much improved and could be run very low very reliably. again i think the lesser resriction to the valve allows a higher gas velocity with the larger carb size. at any rate idle is gratly improved with this modification.

    I guess the next place to go from here is to rework the intake manifold and bell shape the port on the reed valve end and maybee try to enlarge the intake port some and see if i get even more rpm increase. If I dont i guess then i need my new ignition to see if i can get more and then i will know there is a rpm limiter built into the stock ignition.




  16. #91
    diceco's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    If you put a smaller prop on it to unload the motor and run it up that would tell you if there is an electrical RPM limiter in the ignition right?

    Will try and get a pic of the slotted cylinder.

    diceco

  17. #92
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Man thats a good idea. Unfortunatlyy I dont have a smaller prop and hate to spend the money on one. I wonder if one of the club members has one i can borrow.

  18. #93

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    The 2 ring one that I found was on a Troybuilt/MDT with a date stamp of March 15 2006.It was stamped on the head.It was also a long shaft.

  19. #94
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Did you by chance have the model number and the serial number.

    Here is a link i found that may be usefull.

    http://www.outdoordistributors.com/R...rts_Lists.html

    Far as I can tell if it say ring it is just one ring. If it says ring set it probably is a two ring set up. you cant really tell in the picture. It seems that there arent to many that is a two ring set up. you really have to search through this too.

  20. #95

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    I am also interrested in the Ryobi.I have been working on then for awhile.I ordered a conversion kit a long time ago.It was the cost of the EI units that kept me from going further with it.Now that there are other less expensive units out there I have been working on it again.I have found that there have been differant head castings,crank/lower body,pistons,mags,carb sizes and the back covers.

    The only thing I found NOT differant with all but 1 is the rod.I have one that looks like an I-beam.

    The pistons are about the same weight.But they are differant.Some are longer skirt,some have a differant side relief for the crank,some are full round cylindars, and some have a bevel to the top lip on the piston.Also some of the ring are differant thickness,some pinned some not.Most do show the gap blow-by burning.

    I have not run any of these yet.I am still working on them.

    The oldest one that I have is the one the has got my attention the most.It has a differant head.The exhast measures 1.1405 in. wide x 0.38 in. high and 0.084 in. from the bottom of the head to the floor of the exhast.Also it is the heavyest one.

  21. #96
    combatpilot's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


  22. #97
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    A couple of years ago, I had an engine that just wasn't putting out what I thought it should. It started fine, idled and transitioned well, and flew well. But it's top end rpms weren't what I thought they should be. I took it apart, and found a ring gap of about .012". Specs call for a ring gap on these size engines of around .003" as optimum, (which by the way is a very tiny gap). So, I ordered a Frank Bowman ring for it, and installed it at Frank's recommended zero gap. I ran it rich for one tank, and then leaned it out and check the rpms. It gained over 800 rpms!!

    The Ryobi has a poor design for the ring pin. The pin that keeps the ring from rotating takes up the whole ring land, instead of taking only half as do most other two stroke engines. This makes for a ring, brand new, that necessarily has a very wide gap. When you install a Frank Bowman ring in a Ryobi, you either tap or grind down the pin so that it is only half as deep as the ring land. Then his ring is fashioned so the part of it fits over the pin, providing a gap of zero, or near zero. This helps power tremendously on the Ryobi!!

    BTW, thanks for the reports and all the hard work to obtain them. Good work! Now try a Bowman ring!!

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  23. #98

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Check this out Ebay item # 120386237567 41.5cc RedMax Zenoha??

  24. #99
    ckangaroo70's Avatar
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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)


    ORIGINAL: combatpilot

    hey look at this

    http://search.cartserver.com/search/...words=753-1207
    There you go. I have bookmarked that page, and if I am to dissapointed with my rpm numbers when I test my engine I may be rushing to get an order out for one of those 2 ring replacements. Thanks for the good link.

  25. #100

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    RE: another darn ryobi post (ryobi performance modification, analysis and comparison)

    Troybuilt TB20CS 31cc It has 2 rings 4 ports and long shaft


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