Hi everyone!

In case anyone is interested or can help

I decided to do an airplane conversion on my Homlite HB100 25cc leaf blower. The engine will ultimately end up in my 70" P47 if it hasn't blown up before the end of this experiment. After loads of hassle trying to get 10/10 glo fuel I managed to find some Morgan 20/10 at my local hobby store! When I got home I mixed it with premium gas at a ratio or 1 part 20/10 to 2 parts gas only to find that it refused to mix!!! The fuel would stay cloudy and separate within a couple of minutes! So I mixed in some acetone, a drop at a time whilst stirring it until it went totaly clear. I don't know exactly how much acetone I put in but it was a very small amount, I Just kept dripping it in while stirring the fuel until it went clear. I filled the tank on the blower, gave it a couple of pulls and it started! I'm still using the stock ignition as this is the first step just to see if it runs on that mix. Well it ran like a bucket of bolts! I adjusted the hi and low mixtures so that it idles and revs up to the same limits as before when it's running on straight gas/lube. Now it runs like a train!!! The only problem is detonation when the engine is accelerating! I knew that would happen as I am still using the stock ignition on the factory settings. hopefully when my glow adaptor arrives that will change and I will reset the carb again! The fuel has now been sitting for an hour with no visible signs of separation! I will be testing this engine in it's original home ie; the leaf blower (My garden needs doing anyway ) as it is under more load and heat then on a test bench or in an airplane. When I have finished I will remove the engine from the blower and all the unnecessary ignition components etc. and do the final testing and adjusting on the bench before the instalation into my P47. Any views or help on this experiment would be much appreciated.

Thank you

Richard

The Gas/Glow thing is fun, and I have 5 airplanes running Gas/Glow, from 23cc up to 48cc. I find they make more power, start slightly easier, idle slower and smoother, etc. We have found that a quality four stroke glow plug seems to work best.

Is that glow fuel you used 20% oil, or 20% nitro?? If it is 20% nitro, you might find a colder glow plug will work better once you switch to glow operation if you encounter detonation.

As I have mentioned many times here, the standard Gas/Glow mix with 10/10 glow fuel in it ends up at a final oil ratio of approximately 32:1. This is slightly heavy on oil, as most gas engines have a 40 or 50 to 1 recommendation for oil content, but it is not excessive and will be fine.

Doubling the oil content as one does when they use 20% oil glow fuel in the mix, is sure to cause problems with carboning up the engine and is also likely adding to your detonation problem. Further, that extra 10% oil also means you have that much less methanol in the mix, which might cause problems with glow operation, which depends on the catalytic reaction with the methanol and the glow plug to work.

Good luck and have fun,
AV8TOR

Hi AV8TOR

Thank you for your reply. I have read your posts on this subject and so far they have helped me a great deal. Ok I have just been in the garage with that damn leaf blower!! At the moment I am running 1 part 20/10 glo (20% Nitro 10% Oil) to 2 parts 84 ron gasoline and a very small amount of acetone to bond the gas and the glo. I'm using an OS type F glow plug. Now I have just spent half an hour in the garage trying every possible mixture screw combination and that damn engine won't stop detonating! Apart from that it runs better then it ever did on gas and yes it will run upside down without hesitation or rpm drop without the use of a glow plug driver. I just wish I could stop the thing detonating before the engine goes bang!!!! Do you think droping the nitro mix to 10/10 or using 93ron fuel would help???

Rich

Yes on both questions.

First, the standard Gas/Glow mix calls for high test, or premium gasoline. We went to this because we encountered some detonation in certain engines with regular gas, and going to premium gasoline solved that problem. Second, you are running double the recommended nitro, and aparently that is just too much for the compression ratio of your engine.

You can try a batch with your high nitro fuel and high test gasoline and see what happens. You can try a colder glow plug if you have one too. If it keeps detonating though, you will have to go to a lower nitro mix. Detonation will kill an engine fast, especially a two stroke, so be careful.

AV8TOR

OK, step number two then! First let me start off by saying that this blower is at least 15 years old and was found in the trash! I had to remove loads of grunge from around the engine just to find the mixture screws!!! I'm amazed that this thing still works even after all the abuse that I and the previous owners have put it through! Anyway I have laid the engine to rest for tonight as it really needed it. Tomorrow I shall get a gallon of premium and mix a new batch using my 10/10. As for the compression ratio God only knows on that one as this engine probably has about 1/2 an inch of coke in there after so many years of abuse! I know all too well about the detonation as I used to build and race 1970s two stroke race bikes. Those damn things, if they were slightly out on the mixtures would seize the centre cylinder and put your backside on the tarmac faster then you could blink! (Usually only when you were well over 100mph for maximum pain and discomfort!!!!!) I'll let you know tomorrow evening.

Thanks again for your help

Rich

Yeah, I remember my old two stroke dirt bike days.... I was young and always had to try and tweak the engine for that very last ounce of horsepower, and it usually cost me a piston and a bore job... [] I'm sure you are familiar with that old saying; "two stroke engines run the best right before they blow up!" But I sure learned a lot and had a bunch of fun!!

RE your engine. Once you get done playing (experimenting) with it and get serious about putting it on a plane, you might want to think about decarboning it and putting in a new Frank Bowman ring. Every used engine I've ever pulled apart needed a new ring for optimum performance, and on an airplane every little bit counts.... There is a fairly easy mod you can do whereby you send your piston to Frank and he pins it for use with a notched/pinned piston ring. Then you can grind the bridge out of the exhaust port for much better flow. It's a really good mod for these engines.

Here's my old Homelite 25cc story...
I once went to a small engine shop looking for engines and they gave me an old Homelite string trimmer. Really grungy and old and beat up. The gas in it smelled horrible and was probably years old. I thought "Well, if nothing else it's a good parts engine." I brought it home and it was laying on the patio floor. My brother stopped by later and slowly pulled the rope to feel how much compression the poor old thing had. IT STARTED UP!! My brother and I just stood there with astounded looks on our faces, while the damn thing layed there on the floor running!

AV8TOR

One thing that might help.

You could add another 2 or 3% alcohol. Try Heet in the yellow bottle not the red.

That would lower the nitro content.

That and an extra washer or 2 under the plug to lower the compression.

Good morning everyone!

First let me thank you for your advice, without it this blower would probably be scrap by now! Ok today is new fuel mix time! As soon as I have my results I'll type them up. Now for an engine rebuild, hmm. This is the deal, the reason I am doing this apart from having fun experimenting is that I haven't flown for twenty years! I really don't want to put a $300+ engine in my plane in case I bury it! Yes I know I should have bought a trainer but my 70" P47 cost $150 brand new and the engine is free! alot less then a trainer package of the same size! I like large aircraft (especialy Warbirds) and they are especially useful here in North East PA where we are prone to high cross winds and wind vaning! I was flying full size planes here last year and boy was it edge of your seat stuff especially in the spring! Now back to the engine. If anyone is interested Homelite.com sells factory reconditioned 25cc leaf blowers for $49.99 plus shipping! You can't beat that!! On top you can add about $50 for the conversion parts from wackerengines.com and you have a brand new 25cc airplane engine for around $100!! If you go dumpster diving in the spring then you can have a usable aircraft engine for $50!!! Can't beat then can you. Oh and they sell 30cc Weed Wackers for about $80. These are returns from like Lowes or Home Depot that for some reason or other didn't work or were purchased in error. They go back to Homelite, they get them working and resell them as factory reconditioned so you are getting a BRAND NEW! Unused motor. As for the rest of the parts you don't use stick them on Ebay and you might get some cash back All good in my book! Also I am not a fan of glow engines as they are expensive, harder to start and eat a horrendous amount of fuel! Now back to my engine. Most likely this engine won't end up in the plane as I would rather put a new Homelite in there. I will be using it for experimentation though! Once this engine is running then out comes the dremel! I will be removing as much weight as possible, closing up all the tolerances and seeing how much power I can get out of this thing without destroying the reliability. I just can't leave two strokes alone can I? Oh any chance of giving me the addy for this Frank Bowman guy in case I need him for future reference? So job for today; Purchase a gallon of 93 and mix with my 10/10, drain the fuel out of my blower, add the new mix and back to the mixture screws again! If that doesn't work, go to my old airfield and get some Avgas!

Av8tor, your homlite story sounds like my Echo strimmer, 2 snowblowers, gas lawnmower and leafblower story!!! lol! And all this stuff works perfectly! I'm not wealthy but live in a wealthy area (go figure) You would be amazed what people throw out here!!!! Especially during the anual spring cleans!!!

Rich

Don't go with the AVGas. Too much lead in it, and it will carbon up the engine and foul the plug. High test, (premium) car gasoline and your 10/10 glow fuel will do the trick.

AV8TOR

LONG LIVE THE HOMELITE!!!!!!!!

Well I tried! Got the gas! Sunoco Ultra 93 and it actually mixed! Made up a batch of fuel and stuck it in the blower, started it adjusted the mixtures again and again and again but I just could not stop it detonating! I took the covers off of the blower only to find the base gasket was leaking! DOH! So the engine was leaning out! Well I took the glowpug out and it was covered in bits of engine! Oh well! Actually under further investigation I also found that the cylinder had completely chewed through the spark plug lead! How it even run on gas is beyond me. On top of that many before have done bad repairs on it so the engine was leaking everywhere! I will be stripping it down in the future to see how bad the damage is though! In the meantime it's down to Walmart for me to pick up a 25cc weedeater!

On a happier note as soon as I gave up on the homelite I got out my Echo 1000 trimmer put the glow plug in that and boy did it run like a trooper!!!! No detonation and hardly any mixture adjusting needed but the only two problems are one it's only 16cc and two probably because of the angle plug head it shrouds the glow plug so it needs a glo plug driver to run at it's maximum.

The 21 to 25cc Echo engines make great conversions, (and run really well on Gas/Glow), and weigh only slightly more than the 16cc.

AV8TOR

Yes I do agree, Echo engines are really good unfortunately the trimmers also cost about $200 to $300!!! I think Walmart beckons as the Weedeater Featherlite Xtreme is only $90 The whole trimmer only weighs in at 8lb so just the engine block, carb, exhaust and glow plug should be very light. As I have said before Homelite also sell recon blowers for $50

So in your experience which would be your preference between Weedeater or Homelite?

Rich

Homelites are very good engines as well. The Weedeater Featherlite can be ok, but you're going to have to do some serious porting, etc. to get enough power out of it.

AV8TOR

Thanks again AV8TOR!

Looks like the homelite is in the lead at the mo! Cheaper as well So you can have your cake and eat it

Richard

You don't need to buy, and especially new.

Go to the local small engine repair shop and ask if they have any old engines you can have.

The first time I did this I got 10 Echos. and all but 3 had good piston and cylinders.

Look for SRM-2300, 2400 and 2600 series string trimmers. The 2100 series is okay, but small.

Hedge trimmers are a 2 ring engine.

Homelite: Look for the 33cc chainsaw. Easy to convert plus it weighs the same as the smaller engines.
The one with the black airfilter cover are suppose to be the best ones as far as performance.

You can build a conversion engine for less than $100.00
And it will run as good as a new engine off the self.

Thanks again AV8TOR!

As usual you were 100% spot on! I went to friends house last night to try his new Weedeater Xtreme 25cc trimmer. Damn my 16cc echo has more power! So when I came home I ordered a factory reconditioned Homlite blower from www.homelite.com. It cost $49.99 plus $10 delivery. I was going to go down the route of asking the repair shops to find me a cheapy but time is short and I prefer a brand new one as I know the engine is good! I will try and locate scrap echos for future projects in the meantime. All these new engines in the shops seem to be low compression for easy starting and set up for California use so they are strangled to death for low emissions and noise. I assume then that only the old engines are good for this sort of conversion unless you like spending hours porting and modifying. Unfortunately I work long hours and I am also trying to set up business repairing clocks so time is not always available for me. Thanks Ralph for your advice I will look for some scrap echos for future projects.

Rich

WOW! 24 hours after ordering my 25cc Homelite blower it was on my door step! Looks brand new and it only cost 49.99 + 10 delivery! Seems a shame to tear it apart now! That's one hell of a cheap airplane engine!

If anyone else wants one;

www.homelite.com and look up the factory reconditioned machines.

Rich

You might concider running a few tanks of gas through it to break it in.
That way the wife will think your working when in fact you testing your next engine.

Another thought ... If something goes wrong when it's still a blower you can send it back.

WIFE!!!! Been there, done that, bought my lawyer a Ferrari!!!!!!!!!! As for the girlfriend, gone past caring! As for the blower, yeh I will run it an a few tanks to run it in, my garden needs doing anyway. The great thing is they sent me the wrong one! I ordered the 25cc version and they sent me the 30cc for the same price! I'm happy all round

Oh that's cool. I was going to tell you that you should have gotten the 30cc instead, but I decided not to as I didn't want to bum you out. That's great that you got one anyway.

The 30cc is a good bit more powerful, and weighs an ounce or two less than the 25cc believe it or not.

AV8TOR

Hi AV8TOR

I was thinking about the 30cc but though it was going to be way too big for a 70" P47, guess not then. Is it a good idea to swap the carbs with my old one? This new on has a tiny California emission carb! I started another thread re what carbs can I use on this engine. I know you mentioned the WT645 and someone else mentioned the WT433 and WA167 but I haven't seen them for cheap on ebay yet. Will any 11 or 12mm Walboro carb fir or do they have different stud patterns etc.

Ok, next installment!

The new blower works perfectly so after running it in I'll convert it! Now for the 25cc; I have just stripped it and found the following; 1- It would't run on Gas and standard ignition as the cylinder head had completely cut through the ignition lead! 2- The detonation was caused by a leaking base gasket leaning out the mixture. The engine is actually in remarkable condition considering the fact that it's at least 15 years old!!! There are no scratches on the barrel or piston and no signs of damage from the detaonation although the piston does show signs of ring blow by. The crank, big and small ends have no play and the bearings rotate smoothly. There doesn't seem to be any weeping from the front seal, so all in all a good useable engine. Now for the questions;

Does anyone know why there is a small square lump on the top of the inlet and if I remove it will I need to pin the piston ring? Also the engine is fitted with a Zama CIU H11E carb. Can I use this carb on my 30cc? and is it any good for aircraft use. Can I cut down the inlet manifold so that the engine fits in my cowl or will upset the inlet pulses etc.

Oh in case anyone is interested, this engine as is, with ignition, carb and exhaust weighs in at a hefty 4lb 10oz!!!!! Better get the dremel out!

Thanks

Rich

I have heard some people were having problems with the ZAMA carb on glow/gas, i would stick with a walbro.

Unfortunately these two blowers came with the Zama. What problems were they encountering?

Iv'e been busy with the saw today and managed to get the engine down from 4lb 10oz stock straight out of the blower to 3lb 2oz with the glow conversion with stock muffler, propshaft (steel tube and steel washers) and carb. Now out with the dremel this weekend to see how much more I can remove. What is the minimum weight that anyone has got these engines down to?

Rich

Ammend the above! unfortunately I have just been told by Whackerengines that you cannot run a Homelite without the flywheel as the flywheel dampens the resonance from the crankshaft! Without it the crankshaft will break! DOH! Back up to 3lb 14oz!

Rich

Minimum weight is not important.
It's getting it to balance in your airplane with out adding weight that counts.

The problem with the Zama Carbs. and Gas-Glow isn't much of a problem.

You put Gas-Glow in the Carb. the diaphram goes away ...... No Problem.