RE: Who is converting Toro trimmers?
 

I actually don't go up at all. I just square off the port. If you look inside the port is V shaped on the bottom. I just square it off so it is even on the bottom. It is not much but it doies help. I am going to do some more mods on the nevt one. This one runs so good and has lightning fast responce so I am going to leave it as is.

RE: Who is converting Toro trimmers?
 

I have to buy some APC props, I have to see what the difference is compared to the props I am using. Those are good numbers for a 1 bbl engine you are getting. This first engine of yours is basically what I did to mine, except I have a Zama carb. I"ll try the APC prop next, but I also think I can make a low profile carb spacer to fit this Zama and I'll make a muffler also. By the way what is the altitude of your location, I think you are higher than Pennsylvania and you are still getting better numbers.

RE: Who is converting Toro trimmers?
 

I am only around 1000ft or so. The barometric pressure today was 30.11. APC props are far more efficient than most so the RPM will be higher with them. I ran a 18x6 Dynathrust and it was 400 RPM less than a Pro Zinger. It also turned a APC 17x6 at 8500 or so.

RE: Who is converting Toro trimmers?
 

What is the ready to fly weight of these engines?

That's everything including the prop and the mount.

RE: Who is converting Toro trimmers?
 

I don't use a mount. The back of the engine is perfect for mounting. The weight RTF on the engine I just did today (pictured) is 3 lbs 8.5oz. Less than a G26.

RE: Who is converting Toro trimmers?
 

Balancing flywheels, now that can be a challenge. I have heard about balancing flywheels for years, but I never saw how anyone does it. (There must be electronic devices for this used by the big companys.) I decided to build my own balancer. I found some very small precision ball bearings with close to 1/8" I.D. (actually a hair less, metric?) and I used these. It actually works, I have balanced a few flywheels, but it is a tedious process where something like a crystal ball would also help. More than once it looked like "remove a little bit more about right here and that should do it", but it does something different than expected. Experience and learning when to leave well enough alone helps with this process. Sound familiar Scott? or do you have a majic wand for this?

RE: Who is converting Toro trimmers?
 

Your altitude is close enough to mine. I looked at the picture of the engine you just posted. One thing you are using that I haven't used on a Toro is a velocity stack, that could affect the results? I will check a few other props for operation, mainly as a curiosity, and I will use the Laser Tach when it gets here, it will no doubt give more precise readings than my Tachmaster. The bottom line is that when these engines are running well and producing power, you don't even need a Tach, except for testing like we are doing, because you can hear and feel the power. A stock trimmer engine sounds like a trimmer engine, but when modified and hopped up a bit, they start to sing like a glo engine. I know you have noticed this.

RE: Who is converting Toro trimmers?
 

Those are some good numbers for the 1 bbl engine. I have one that I did essentially the same exhaust only clean up to. I will recheck this will the Laser Tach. You mention a 12.7MM carb, is this the venturi diameter or what?. I have noticed that the venturi versus the bore diameter of different numbered carbs varies noticeably. 12.7mm is .50" so I would expect that this is the bore at the throttle plate, is this correct? With the Zama carb that I am using, the bore at the throttle plate is .56" and the venturi looks real close to .375". (I can't actually stick the calipers in there without removing the choke.) Dave thought my carb could actually be too large and I considered what he said, but it runs very well. An identical carb gave me very close to 8000 RPMs with a 25cc weedeater with the same 16-8 prop. Of course I opened the ports on that engine and the throttle response is very good, which is a vote for a good carb match. So, I figured the Toro should be able to handle one of these carbs.

RE: Who is converting Toro trimmers?
 

Hi Rollmyown,
It sound as though there is some confusion about carb size. Carbs are sized by the venturi diameter. Walbro carbs have a number cast into the inlet side of the venturi. This number is in 64th's, so 28 equals 7/16ths or 11.11mm. 32 64ths equal 1/2" or 12.7mm and so on. Zama carbs don't have this and must be measured with a drill bit shank or caliper. I have seen the same Zama carb model with two different venturi sizes. The next thing is the throttle bore which I find to be 5/8" on all of my Walbro carbs 11mm and above. I don't have any large Zama carbs since all of mine are off trimmers. The throttle bore varies on the 10mm and below carbs from 7/16ths to 9/16ths depending on what the manufacture wants. When you told me that you were using a 14mm carb, you were talking about the throttle bore and I assumed that you were talking about the venturi size. Your carb is actually a 8,10 or 11mm which is fine for a 25cc engine. I guess the big test is to try the Toro with both 11mm and 12.7 and see if there is a gain. If there is no gain, the 11mm will give better endurance. Another interesting experiment would be to make a manifold in three or four sections to test fly and see if a shorter manifold is OK. This would make cowling easier.

Dave

RE: Who is converting Toro trimmers?
 

What do these weigh with out the flywheel?

RE: Who is converting Toro trimmers?
 

I use a Dubro prop ballancer. It is pretty acurate but not perfect. I get them close enough that it looks like the magnite is the only thing effecting it and not the weight. It is not perfect but very close. I need to replace the beams that hold up the balancer wheels with stainless or alluminum. That way the magnite will not effect the outcome. The Toro flywheels are pretty close anyway. I usually do not need to remove much.
The velocity stack is a good idea on any gas engine. When I put one on the toro I had to lean it quite a bit because all the gas wasn't being sucked out of the carb by the prop wash. Also it picked up 200 - 300 RPM. It doesn't effect all engines that much. But the toro it did. The muffler also helps alot. I used a 1/2 id single pipe before but now that I switched to a single 9/16 id pipe the RPM's are higher but the noise is the same.

RE: Who is converting Toro trimmers?
 

I would have to check the weight without the flywheel. You are thinking glow or electronic ignition? I think the flywheel is 6oz or so.

RE: Who is converting Toro trimmers?
 

I usually used a 11.11 mm carb on the Toro. A WA 58. I tried a 12.7 on the last one. There was no increase in top end power but the throttle responce seemed a little faster. I have a bunch of the 12.7mm from new Mac 38cc saws so I figured I would try them since i am now out of the new WA 58 carbs. I should never have sold any of them :(

RE: Who is converting Toro trimmers?
 

Hi Ralph,
I have a 1bbl engine. It weights 55oz. complete with mag ignition,hub,stock muffler and 11mm Walbro carb. Without the coil and flywheel it weights 43oz. Add the electronics and battery and you have close to the same weight as the mag version. The stock muffler weights 6oz. compared to 4oz. for a Wackerengines muffler. The flywheel was not trimmed yet, so thats an extra oz.

Dave

RE: Who is converting Toro trimmers?
 

Hi Ralph,
The untrimmed flywheel weights 8.4oz. and the coil weights about 5oz.

Dave

RE: Who is converting Toro trimmers?
 

There is a thread going that is basically about converting gas to glow.

They are mixing Gas and Alcohol 50/50 adding oil and running a F-4 glow plug powered all the time.

The results seem to be as good as with the standard gas/oil mix with a mag.

It seems to me that taking 16 ounces off this engine for a flying weight of 39 ounces would allow it to be used on

on a whole range of planes.

Now I'm wondering if I should of waited to buy my ST-2300 for my 90 size Groovy.

RE: Who is converting Toro trimmers?
 

Hi Ralph,
As I stated in a previous post the engine weights 43oz. without the coil an flywheel. This is with the stock muffler which is 6.4oz. and a 1oz. spark plug. It would make a good choice for gas/glow operation. The untrimmed flywheel and coil weight 13oz.

Dave

RE: Who is converting Toro trimmers?
 

I have converted a few gas engines to glow. One was a Poulan 42cc. It ran perfect. No glow driver needed. That was mounted upright. Mount it inverted and you will need one. FOr my mix I used 1 gallon of car fuel with 20% nitro mixed with 2 gallons of pure methinol. The result was 5% oil and 7% nitro. Approx. Not as cheep as gas but still not bad. I think the Toro would be a great one to convert to nitro. I just hate the thought of onboard glow on an inverted engine. More money and more weight with the big battery you will need to fly for a good period of time. Otherwise it is a great way to go.

RE: Who is converting Toro trimmers?
 

Hi Dave, I knew there was a bit of miscommunication about carbs and then we had two brands in the mix. What you state in this post is about right. I have noticed there is more than a few differences between carbs also, because they tailor the models to specific engines, of course.
From the "background paper" in your photos, it looks like you have done a lot of research on engines and carburetors.
I already ran a 1bbl engine with a "big" carb and it seemed too big, I covered this in one of my posts. I made an Aluminum muffler, a pitts style, it is 1" thick x 2" wide x 5" long. I haven't run it yet. You have to Aluminum weld this muffler, but you have already seen the aluminum stock, it is scrap pieces from Aluminum railings and it has a .060 wall thickness, which is about perfect to make a muffler. I tried thinner material and it is a pain to aluminum weld without burning up.

I am talking about the aluminum rods and a propane torch. I have made other rmufflers from this stock. The paint smells when it burns off but that is how it is. I bet that garbage man engine supplier of yours might be able to come up with some of this railing scrap, lol.

It weighs 4 ounces, the stock muffler weighs 7 ounces, and the stock muffler is a lot thicker. I am going to make some 1/2" thick carb spacers. (The two bbl engine is more of a challenge for a carb spacer than a 1 bbl engine. I am going to try and do it without an external pulse line.) I would like to get the total width of the engines minimized. I will post a picture of the complete engine when I get it done. I am now thinking about designing an airplane for one of these and around 7" or so in width is a lot.

RE: Who is converting Toro trimmers?
 

I have the ballancer but come to think about it, I was so busy checking other things I didn't think to check the balance on the Toro flywheels, but I will now. I also noticed the velocity stack on the Fuji engines, simple and compact, and should be easy enough to make out of plastic stock. The muffler I just made has two 3/8" I.D. (actually a bit larger, the O.D. is 1/2") pipes on it. I want to finish everything complete before I run them again. I am adding photos to this. A 3/8" carb spacer is shown, there is no gaskets yet, but it is all assembled. The gaskets are easy but getting the carb close to an engine requires doing something to the throttle linkage and the photos show my approach to this. I almost forgot, if you can see the notch on the right of the spacer, that is a new holding spot for the throttle return spring so the throttle servo won't need to fight with a typically tough spring on these carbs, there is still plenty of return pressure. (I try to get the details, it has become a habit.)

RE: Who is converting Toro trimmers?
 

This is a reply to my own post because I ran this engine today. The muffler as described earlier worked great. It is 1" x 2" x 5" which adds up to 10 cubic inches for reference, and it is not as restrictive as many Pitts mufflers. The reason for the post is that this engine really ran dirty, I double checked the carb settings and can try another carb, but something just occured to me. A lot of us would like to get the carb closer to the engine to cut down the overall width and this is what I was after. Now is there any comments on the possibility of a shorter carb spacer causing the spark plug to get as black as it did in about 1/2 hour. When I first started it and set the carb, it ran great, but the longer it went, the worse it got as the carbon was building up. Its a new carb and I have other carbs and both brands, but I am still wondering if a typically 1" high carb spacer is required as part of the intake circuit. Anyone else experienced something similiar?
I was using a 50:1 gasoline mix, but it didn't run this dirty when I tried 32:1. There was no smoke coming from the exhaust. The only hint to what was happening was when I pulled the sooty sparkplug, and it was clean when I started. I find it hard to believe it is the short spacer, but I am not positive. I have an ignition analyser and that is next to try.

RE: Who is converting Toro trimmers?
 

Hi,
What kind of oil were you using? Where you using the NGK plug that came with the engine? Some oils form lose ash in the cylinder and piston crown. Lawnboy ashless is good for breakin. I don't know what oil Scott uses, only that he uses a low percentage of oil because of close tolerances. I think that the long intake on the trimmer is to isolate it from the heat of the cylinder. I don't think that it caused the ash buildup. It could be augued that the thicker insulator provides more time for the mixture to atomize for greater power. How was the RPM and what prop?

Dave

RE: Who is converting Toro trimmers?
 

Hi Dave, I am using SuperTech oil from Wal Mart, until I find a good one to use instead. I use this in a chainsaw and trimmer also. I think I figured this out and why I don't get the revs that Scott gets. I now have a WT 324 carb, and I now know from the Walbro info posted on this thread by others and you that it is a 11mm venturi. I visually checked it against my Zama and the Zama is only about 9mm. With a less restrictive muffler and the Toro's ability to draw fuel even without the carb pump working as I accidently proved, (I accidently put the carb spacer on upside down, the pump didn't work, but the engine still ran) I think a too small of a carb is probably not supplying enough air for proper combustion. There is definitely enough fuel. Here is a photo, the Zama is still bolted to the engine and the Wt 324 is besides it. (My problem has probably been a too small carb all along.) Working on too many engines, and projects, at the same time doesn't help either. I sure am using the NGK plug, it is a resistor plug and have you ever tried to find resistor plugs for chainsaw/trimmer engines locally? NonResistor plugs are easy to find but I had to order resistor plugs online.

RE: Who is converting Toro trimmers?
 

What tolerances would require the use of less oil ?

RE: Who is converting Toro trimmers?
 

Good question. I personally think that different oils have different film strenght under load and heat conditions. So if you use lower percentages it has to be formulated for that application. I think Poulan oil is forulated for 32 to 40 to one mix. 50:1 might be a little low.

Dave

RE: Who is converting Toro trimmers?
 

The tolorences I am speaking of is in the mating of all the surfaces. Close tolorences make a better tighter fit. Good quality bearings, close fitting piston, and so on. The more sloppy the fit is the looser the tolorences and the more oil required to make the engine run correctly and reduce heat. A Toro is 50:1. Any oil will work. Some lube better than others. Most Stihl engines are 50:1. Poulan engines as far as I know are all 40:1. If you look at the directions on these tools they say a good quality oil but always the same ratio. Not 40:1 for one oil and 50:1 for another. The oil mix Toro says for the 25cc wacker is 50:1. I use lawnboy ashless for break in. Then a good synthetic after that. Amsoil or somthing works well. Just be sure to use a non synthetic oil for breakin. The rings will not seat well with synthetic oil. It lubes too well.

RE: Who is converting Toro trimmers?
 

I will have to agree to disagree..The old A&M gassers were loose as a goose right from the factory..Seems like the recommended ratio was synthetic at 100-1..
From the Zenoah G26PU (aircraft_ and PUM (marine) factory specs....Standard clearance between piston and cylinder is .00118 to .002...Considered worn at .005...Recommended oil ratio is 25-40 to 1...
So a piston/cylinder fit of .0011 is OK with 25-1 oil...Kinda blows the theory about oil ratio for closer clearances...NO gasser will run for very long with a piston/cylinder fit of less than .001, so I highly doubt the "precision fit" of a Toro is any closer than that....;)
Clarence Lee once said that oil helps carry heat away...I will not dispute that[>:]

RE: Who is converting Toro trimmers?
 

Hi, you bring up some interesting points. We all know that in an automobile engine, and other 4 strokes for instance, oil definitely figures into the cooling. Clarence Lee, of which I am also a fan, was probably talking about 2 cycle engines and their high percentage of oil and using this oil to carry heat away more so than the low oil content of these "gassers" ever will. The Ghnome rotaries did the same thing and gave the Pilot a grease job in the process. What do you think, do you agree? These oil ratios for 2 cycle chainsaws, trimmers, etc. do get a bit vague to sort out, but I think it has a lot to do with the quality of the oil. Oil technology has changed a lot since I first started using oil for anything. Its amazing to me that anything gets lubricated at 50:1 or more so at 100:1. At the old 16:1 ratio, the gas turned the color of the oil, but at these higher ratios it is a lot less noticeable. It takes awhile to lose our skeptisim, thats only natural when we have been doing something else for years. I now use only synthetic in my vehicles and my lawnmowers. The first time I put synthetic in a lawnmower, I had to walk faster, it sold me. A 100:1 ratio for 2 strokes would bring out the old skeptism in me, it is only lately that I began using 50:1 because of this thread and knowing others are doing it.

RE: Who is converting Toro trimmers?
 

Agreed:D
I'm not totally convinced on the synthetic at 100-1 VS petroleum at 32-1 thing...I kept adding oil to some fuel last week...It ran the same until too much oil caused it to quit..I picked up 200 rpm once years ago on a Zenoah 445 twin by running 20-1......
I have some Amsoil 100-1 here, will try it VS Pennzoil 2 stroke at 32-1 in the same engine, same prop, same everything...

RE: Who is converting Toro trimmers?
 

I have used Opti-2 for years now. It's a 100 to 1 non synthetic oil.

I ran it at a 100 to 1 for a year or so, but found my big saw developed more power at 75 to 1.

I assumed it was because of better ring seal.

I have never mixed it with alcohol, but it was reformulated to be used with gasohol.

It's suppose to be drawn to heat instead of repelled by it.

Opti makes a 4 cycle oil also that doubles the manufactors engine warrenty.

RE: Who is converting Toro trimmers?
 

The Toro engine is interesting with the 2 barrel carb, but you've got to understand why its there. Its not for performance, its to introduce a clean air charge into the cylinder to purge the exhuast gases with fresh air, not air/fuel mix, therefore reducing unburt fuel emmissions from the exhaust. I'd be pretty certain you'd get more power from one of these by just using a conventional carb and plugging the transfer feed pipes directly into the crankcase to supply them with air/fuel mix rather than just air as per the standard setup. In effect you end up with areas in the cylinder where there is no fuel/air mix, just air, so thats got to limit its performance although reducing emisions.

Just food for thought.

Cheers,
Rich

RE: Who is converting Toro trimmers?
 

I just picked up some of these.
I have both the single and two barrel.
At this point, I have to say that these engines are up to par, quality wise, with the Zenoah
engines. The castings are very clean, and the machine work looks flawless. Even the
gaskets are high quality.

Some observations of the single barrel model...

The engine weighs less than a G23. The main reason is the thinner cylinder castings.
This may be an issue when opening the ports, as there isn't much material to begin with.

The intake and transfer ports look to be of decent size. The exhaust, however, seems tiny.
It probably has half the area of the intake port. Again, not much material can be removed
but I think the major gains are gonna be found here.

The rotary carb may work, if you prop it to suit the carb, as I see no way to adjust the high speed mixture, and the low speed seems to be covered with epoxy.

The long plastic intake block (heat dam) can be replaced with one from an Echo GT model trimmer, allowing the use of a "conventional" carb, without the need to go with an external pulse line.

The stock muffler seems excellent! Large volume and decent outlet size. Only testing will tell...

I have big plans for these engines.
This may also be the perfect "sport" boat engine!

More to come, and I will have pics...

Joe Petro

RE: Who is converting Toro trimmers?
 

Hi Rich, Since you offered an opinion on the Toro with the 2 bbl carb, I am replying to you with a few comments and a couple of photos to see if what you say and a few of us have been thinking and tinkering toward with the 2 bbl Toro, is actually possible to happen. Have you actually seen one? We know that there is an emmission component to the design of this engine with the Reed system. What we don't know is did it meet the design goals. By chance are you one of the designers?, before I put my whole foot in my mouth. The piston does not travel far enough down on the downstroke to completely uncover the two directional ports in cylinder walls. If you haven't seen one, these ports are the only ports into the cylinder and are shared by the transfers from the "main" intake port into the crankcase under the carb. If the main port and the Reed ports were two different systems this arrangement would be easier to understand but as it is, it is not. The Reeds have a very short duration of time to do anything so if any gains can be made by feeding more air/fuel through the rubber hoses to the reeds remains to be seen, but not for much longer. I just finshed an adpter plate with transitional porting to go from a cut down and slotted 2 bbl intake manifold to a WT 324 carb's 5/8" (about 15mm) at the throttle plate bore. This was a challenge to do and I haven't run it yet. I still need to make a throttle linkage for a servo, but I can run it as it is. I got tired of wondering, and speculating, and just started working on it. We shall see now. Here is some photos. The engine with the aluminum extended linkage is a 1 bbl engine with a low profile carb spacer.

RE: Who is converting Toro trimmers?
 

Hi John,
Does the 2bbl carb have fuel nozzels in both barrels? If they do, the air injection idea is not workable. Reed valves open and close in response to crankcase pressure changes, so they open earlier on the up stroke and close earlier on the down stroke. This can lead to improved port timing since they respond to demands of the engine rather then fixed symetrical timing of a piston port. Maybe Toro was trying to get a little extra boost on the up stroke for more torque. I think that the piston skirt extentions which block the transfers are ment to assist the reed valve function. You sure have been busy.

Dave

RE: Who is converting Toro trimmers?
 

Ralph, did you get a chance to run those oils back to back?? I'd be interested in the results.

Thanks,
AV8TOR

RE: Who is converting Toro trimmers?
 

Do you mean did I try the Opti-2 at 100 to 1 and at 75 to 1 back to back.

The answer is yes. And there was a considerable difference under load.

The saw was a Stihl 088 it was 121cc. In smaller saws the difference was not noticeable.

I had surmised that the difference was piston ring seal.

RE: Who is converting Toro trimmers?
 

Hi Rollmyown,

I'm not the designer, or anything to do with the engine manufacturer (its used in a few different brand names) I was just interested when it came out as its a bit different, so I found out why and how it works. You probably already know this but the throttle bore to the reeds is air only, all air/fuel mix goes through the other barrel and direct to the crankcase. The reeds are only open for a very short time, the idea being a fresh air charge leads the air/fuel mix into the cylinder so the air only charge follows the exhuast gases out, so no unburt hydrocarbdons exit the exhaust. As soon as the pressure from the crankcase forces the air/fuel up the transfers it closes the reeds and allows air/fuel into the cylinder. I've got some images but its on my PC at work, I might be able to post them up next week.

Hope that makes sense, its a very well though out engine and well made, just a shame they did it for emissions not performance! What we need is a 12000rpm trimmer engine LOL.

Cheers,
Rich

RE: Who is converting Toro trimmers?
 

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RE: Who is converting Toro trimmers?
 

Hi diablo_r and Dave wallace,
I hear what you two are saying and I got tired of wondering and guessing what would happen if we did what I am trying to do now. Rich reminded me that I didn't notice a fuel nozzle in the second barrel of the carb, and you Dave are asking the question directly. When I first tried my slotted intake manifold approach (modified the Toro intake manifold), it seemed as though it was going to work, so I cleaned up the intake a bit more and opened the directional ports in the cylinder etc. This caused the engine to run great until the second barrel began to open, then it would bog down. Looking back, of course it bogged, it was too lean. If I blocked the second barrel with a finger it ran ok. At that point, I thought I am spending too much time on the problem and just wanted to move on, so I went to work on the 1 bbl engine again. Rich stated in his initial post that there was no fuel added to the second barrel, just air. That stirred my curosity again, of course, Rich is right, no fuel - it was too lean. I knew that sometimes with carbs a too lean and or a too rich condition can be confusing so I was just going to drop the idea and then along came Rich. O.K., I already had it figured, how to do it with a Walbro carb, so I would do it and find out if there is anything to be gained. I still have not had the chance to run it. The photos in the previous post show a WT 324 carb and I have a few larger ones. A family wedding and a few other things came up. I don't think I would bet on how it will turn out, as far as more performance is concerned. I will probably run it tomorrow. I will post the results.

RE: Who is converting Toro trimmers?
 

Hi Dave, I replied to you and Rich in another post. It is hard to try and figured out what will or can happen if whatever, and since I went this far, it has a Walbro this time, I'll just run it and we will see what happens. I will use my Ace Tach and my Sampo Laser Tach to compare them also.