flyjoe540,
I ran it as a weedwacker for 1 tank full of fuel, 3/4 at full throttle and 1/4 at an idle before I started converting it. I used www.wackerengines.com conversion kit with his home made muffler also, maybe the muffler might of increased my rpms some also being it wasn't the stock. I will have pix up tonight when I get home from work.

Like I said before, I don't have too much knowledge yet with these conversions and the mods that can be made to these engines but I am also having a ball with it. I am a HANDS ON kind of guy and I love taking things apart and putting them back together and finding out that it still works, maybe better... It is great. I am definitely going to keep up with this post as I have been learning a lot.

BY THE WAY: Does anyone need any McCulloch 31cc weedwacker parts minus the engine?

Aero nut

I am trying to figure out the ratio of glow fuel to gas. I think I understand but I want to make sure. I use Omega Fuel that is 15% nitro with 17% oil. I believe that means the methanol content must be 63%. If I want to get the nitro & oil close to 3% I would mix 1 part glow to 4.5 parts gas. That would give me 3.3% nitro and 3.7% oil. Is me thinking correct on this? If so can I use the same 11.11mm carb on my 31cc Ryobi or will I have to modify it in some way?

Thanks

Purchased two new (reconditioned) Ryobi weed eaters for conversion the same week. While disassembling one decided to use the other as a weed eater to see how it performed.

The engine being converted has two rings. If you consider ring drag a problem simply remove the bottom ring. If you perform before and after testing a small gain might be observed.

A Google search for ‘Ryobi Engine’ will find several web sites with hop up information. A search for Ryobi in ‘Tachometer Readings’ will also provide a wide range of engine speeds. Most are propping in mid to high seven thousands. I am not optimistic about numbers above 8000 without extensive engine modifications or a pipe.

Bill

I have a McCulloch 28cc eng that I want to convert to glow. I would like to mount it on a Great Planes 60 series Big Stik which has a
66" wing span. Do you think this eng will be too heavy on this plane once converted to glow?

john rc
most of the reading I have done suggest's that any wing with an area of roughly 1000 squar inches will be o.k.
otherwise the wing loading gets too high and you get exsessive landing speeds and other problems .
also if i'm not mistaken the mac. is already on the heavy side .you would need a bigger plane than .60 size to accomadate the extra weight of a conversion engine .
weigh your .60 engine aand your conversion candidate and compare alittle heavy (a few ounces)you may be ok
beyond that your pushing your luck.

BillS
I also purchased two reconditioned weedys for conversion both are twin ring quad port .I cconsidere it winning the jackpot
getting two twin ring engines so no I wont be removing a ring remember these engines have to run for a long time
they are not drag engines that run a few times briefly then get torn down and rebuilt, plus ,I like the extra compresion!
well I hope you are wrong, no offense. If I can get 300 more for the larger carb and maybe 100 more out of finalizing the timing and maybee another 300 from break in, im in the ball park . thats 700 rpm right there on top of the 7500 rpm it turns now thats 8200 doing nothing exotic. also my exhaust port is at 130@ duration should be higher maybe140-145@duration that should get me something .also if I stuff it. either by filling the crank case or milling off material from the back of the case I should gain also. but these last two are bordering on exotic modifications if you cant UN-bolt it ,its exotic to me.so one step at a time now. 50 here 50 there pretty soon your talking good numbers.maybe I'm too optimistic
but its not unreasonable as long as it stays together

flyjoe540 thanks for the reply. The 60 series will handle .91-1.20 4-stroke Engine per the tower site.
http://www2.towerhobbies.com/cgi-bin...&I=LXBMM8&P=ML

The weight of a 1.20 4-stroke is about 35oz.
The McCulloch 31cc converted to glow should be are 3lbs. Your probably right it may push the limits of the stik.

SaCCal 72
that may explane our rpm difference you broke yours in somewhat (wish I had thought of doing that) mine was its first run or maybe yours is just faster I dont know.I too am useing petes parts muffler, hub, mount ,etc. so thats not it . any luck on a carb? I was told by poco242 that any carb from 11mm to 13.5mm will work fine . I have some in the garage on some junk chain saws but its too cold out there for me.
Iknow what you mean about the hands on thing, same here.its very satisfying to build ,alter or otherwise modify something
to do a job for which it was not designed and have it work as well as the purpose design\built one for a fraction of the cost
its almost like stealing legally.
I have always liked doing things myself specialy if i can save a few bucks. Iam familiar with most performance modification
in theory, i've always been a geer head .but never with a two stroke, mostly cars.I've been told there is a two stroke hop up book out there. I'm going to get it. it should help . if you find an outlet for the extra trimmer parts let me know as I have four
sets of assorted parts . for now got to finish that trainer

JohnRC
so, get the BIGGER stick!

flyjoe540,
If you find that book you are talking about, let me know where to get it, sounds like something that could come in handy. Also I agree with you about the GP Giant Big Stick, it is one that I am considering to put my 31cc into. Not the greatest looking plane but it would be a good match.

I got the book, cost $20 and is some heavy reading.
Ken

box car
what do you mean" heavy" ,I hope i'll be able to stay awake to read it !

Its got some good stuff in it. Tuning and porting was real good. I did find out that the exhaust system can rob you of a lot of power. If you have an exhaust with no back pressure you will drop a lot of power, thats why a tuned exhaust adds a lot of power to a 2 cycle. I would give it 3 stars of of 5.
Ken

ken
thanks for the preveiw thats exactly what I was hopeing to hear was in it ,good stuff.

SaCCal72
I found it on amazon ,performance tunning for two stroke engiunes by a. grham bell hope it helps.

Thanks, I found it on Amazon. Sounds like a good book. Finally here are the pix I said I would post. This first post will be after I took all the weedwacker stuff off and then the next post will be after I temporarily put everything together to make sure it ran. If you want to see the first set of pix, check out the 1st page of this post.

Now as I said, this is my first conversion so don't laugh too much. If there is something anyone sees that can be improved or that needs to still be cut off please let me know, I wasn't sure how much I could and shouldn't cut off so I tried playing it safe. I am open to any sugestions. I still need to cut the primer bulb off and I am going to paint the engine. I got Ford Red for the cylinder head and Black for the body. I had to take the pix in my bathroom as it started to leak gas so I ran it to the tub. Took the pix as quick as I could.

SaCCaL72
not bad !I usually clip off the throttle spring where it wraps around the throttle arm so throttle is not spring loaded
but leave the rest of the spring in place for a spacer.
you could cut more off the front where shroud was,I square mine up even with the sides and cut the front flush with the receses in the front . kind of looks like an old cox 0.49 on steroides when i'm done.I'm pretty anal about weight though.
just square up the sides and thats probably good enough, remember were removing weight.weight is our enemy! just be carefull around where the jug and cyl. meet, in the front is very thin.

flyjoe540,
Thanks for your suggestions. Here are two pix I marked on, is this what you are talking about to cut off? Please see pix... Also, I did release the spring tension it is loose I just hadn't cut the hook of it off, I wasn't sure what to do with it, I will cut it off now, thanks...

Looks like the fins on the flywheel could be cut back. Less weight and less air grab. Also engine box could be drilled out with a partern of small holes...again loosing weight. Then put a ignition like RCIGN1 has. Save more weight...no big flywheel. If that is not lite enough... go to glow/gas mix. Good Luck, Capt,n

SaCCaL72
YEP,THATS THE STUFF,just go slow especialy in the front under the jug \crankcase conection its kind of thin in this area
a rule of thumb that I use even when building is that if I cant see what it does ,then, I dont need it .weight is the enemy.
behind the flywheel are four....I dont know, call them ,webs ,flanges whatever, these web's come from the shaft housing
and radiat back into the shroud that you have been cutting on, the top one ,ends at the mating flang for the jug\cylinder
conection.here I leave a little piece to support the gasket flange on the crank case all the rest I remove .it will only remove a little weight (like5 oz)and if your not comfortable doing it, then dont. like I said I'm pretty anal about some stuff weights one of 'em. but whats left of the shroud I would get rid of ,no danger there that'll save you 3-4oz easy .pop the flywheel, zip it off ,re-install front of engine ,done.and it gets rid of potential pinch points near the flywheel(saftey first ha,ha,ha)
the carb spring just ends up looking like a wound wire tube ,it keeps the butterfly in the carb properly aligned so that it doesnt get bound up.
pictures look good ,I need to get a cammera it would help to explain things easyer .otherwize looks good to me
fine job. did you get a plane yet?

Thanks, I will cut all that extra weight off this weekend, I hope I can get that prop adaptor off now. I'll have to use a strap wrench. Hopefully my new carb will be in soon that I purchased from poco242(Scott), I am anxious to throw it in there. As for a plane, I still haven't decided on one. I thought about the GP Giant Big Stick as it would be a good match but it isn't the most attractive plane. I also thought of a Dynaflite Giant Super Decathalon but I am not sure if I have enough room in my apartment to build it nor would my better half want to give up the living room for months on end, he he... Also, I am not sure my building skills are good enough yet to build such a large/more conplicated plane as that one. I have only built one plane so far, Four Star 40. Maybe a Four Star 120 but I want something different. Do you see where I am at here, I just can't seem to decide. Help. uhhhhgggg... I would just like something simple as this would be my first "Giant Scale" plane and I just want to ease into it at first. Something simple/cheap that if the engine ended up not working out, it wouldn't be a big loss. Is there any such animal? Anyway, thanks, I will post more pix when I get the rest of the engine cut down.

SaCCaL72,

Go for the Decathlon from Dynaflite.... Its a very easy build.... only part that was a pain was carving the wingtips...

It builds very much like the 4*...... I built a 4* before the decathlon.

I'm using a 31cc Ryobi on my Decathlon.... I let you know how it goes... should be ready in a few weeks.

Scott

Scott,
Thanks, it was the wing tip thing that was turning me off to the plane, I figured the rest of the plane must be just as difficult. I did have my heart set on that plane but as I said, I was a little thrown off by the wing tip carving. Please let me know how it goes!

SaCCal72\\If you are going to be building a kit and want a very nice flying plane try the Sig 4 Star 120. I know a couple of guy's flying on of these with a Ryobi 31cc and they fly great even with the magneto still on the engine. It would be even better if you convert to gas/glow fuel and loss that extra weight. I plan on building the Tiger Moth that being sold by Nitroplanes. Take a look at this. It is an arf and does cost a little more, but this is a great looking plane and Av8tor is building one right now with a Ryobi 31cc gas/glow engine.

http://www.nitroplanes.com/timo12076arf.html

Good luck with you project