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.

RE: Who is converting Toro trimmers?
 

Hi Rollmyown,
It ought to be very interesting to see what happens. It will be a lot easier to tell how it works after a actual test.

Dave

RE: Who is converting Toro trimmers?
 

As they say a picture tells a thousand words, so 3 pictures should tell all! Here are 3 images taken from the engine tech data which explain the fresh air lead charging via the reeds as I tried (maybe not very well) to descibe above.

Cheers,
Rich

RE: Who is converting Toro trimmers?
 

Hi Dave, Today was test day. The 2bbl engine with the adapter to fit the Walbro WT324 carb on the cut down and modified Toro intake was run today. The Reed intake tubes are now getting an air and fuel mixture. It runs pretty decent and is flyable. The RPMs were 8200. Maybe a larger carburetor still would raise the RPMs a bit more. 8200 is about 500 more than I got before. Scott is getting these RPMs without all the extra work. I think I will leave this engine as it is and convert one of the other 2 bbl engines I have, the way Scott does them, and use a bigger carb than the Zama carbs I tried before. One drawback to making an adapter plate to fit on a modified Toro intake is that you still have the carb sticking way out to the side. I am going to try a closer-in mounting for the carb. The muffler I came up with sounds much better than the original, but I don't see much of an RPM difference. My muffler mounts a lot closer to the engine so I am going to see if I can find some more of the 1"x2" "Aluminum Railing" stock to make more with the stacks on the end this time. With a close mounted carb and muffler, the total width is easier to fit to an airplane and will look a lot better. I fussed with a single barrel engine also, the results were weird, so I think I might have messed up the carb spacer that I made, it was a preliminary design and I tried something different. I junked it and will try a new one. You CAN spend time on these. I don't have the Laser Tach under control yet, I only attached one reflective spot but it must be counting both blades anyhow because I was getting 16K readings. The Laser also does the autoranging bit like VOMs do and that is distracting when you are operating the throttle and watching to keep your hand out of the prop.

RE: Who is converting Toro trimmers?
 

Hi Rich, The photos don't come up large enough, but it doesn't really matter. After I first took a 2 bbl engine apart, I could see how it worked, and as Dave Wallace pointed out Reeds work usually in one direction only and some engines use them for timing the fuel charge into the crankcase etc. I knew about these "Reed" engines, but was never really fond of them, and then I ended up with some Toros. What really got me is that the top surface of the piston bisects the directional ports and the piston does not go down any lower than 1/2 of the port diameters. I looked at that and thought, the fuel charge from the main port in the crankcase area is also flowing through these ports, which are never more than I/2 open!, and then at some point the Reeds must only open for an extremely short period of time, so That is why I increased the diameter of the ports. I then wondered if I went too far, but after all the tinkering it still runs and I gained about 500 RPMs. The velocity of the fuel charge through these 2 bbl engine ports must be pretty high. I made them about 20 to 25 percent larger I would guess, I wonder how far you could go, but I am not curious enough to try it at this point.

RE: Who is converting Toro trimmers?
 

its to auto resize thing the forum does that messes up the pic size. Just click to open it full size, right click and save the pic to your local drive, then open it at actual size (100% zoom) in any photo software.

Sometimes with transfer ports the manuafcturer has the port only half open (actually the port is twice the height) as it stops the ring riding over the lower edge of the port so extends ring life. I don't know if thats the case with the toro.

Cheers,
Rich