Poulan 25 from FL trimmer
 

I just got the new trimmer head for 25 bucks. It is Poulan engine (no marks about size but I believe it is 25cc). It has ZAMA carburator C1U type. It has some numbers but I don't remember now - anyway I can't find the info about the size and ZAMA webpage has just generic informations.

I have two questions tho:

1. Engine mount. On the back side there are 2 screws for mounting fuel tank (at the bottom part of crankcase) and only two screws for mounting back plate (black plastic). I saw some pictures where the engine mount (aluminum back plate) is screwed to the two screw holes used for fuel tank mount. Is it enough to secure this engine with only two screws or you support it from the top of the crankcase too?

2. The carburator's pump is powered from the hole in the cylinder under the intake port. There is a black plastic extension between carb and the engine that has matching holes in the carburator and the engine. I think I need some bigger carb (11mm venturi) something like Walbro. How do you match the carburator preasure pump intake with the hole in the cylinder? Any particular Walbro model fits?

I'm at the airport now waiting for my plane (wireless network is great:D), so I can't show pictures - I will post pictures and more questions when I get home.


RysiuM

RE: Poulan 25 from FL trimmer
 

Mine had (I have three 21's) four mounting bolt holes for the back plate. The plate was the same as one for the Homelite 25.

The 11mm (Walbro WA 167-1) is too large for a 21. I don't know about the 25? The ports are too small in the 21 to use a corb bigger than 8mm.

The gasket that goes between the insulator and the carb has a groove cut in it to adapt getting the pressure signal to the carb if it is not aligned with the engine hole in the beginning.

Enjoy,

Jim

RE: Poulan 25 from FL trimmer
 

Wackerengines lists a mount for the newer Featherlite Poulans
Shows a standoff that screws to the tank mount plus the backplate mount
[link=http://prophub.tripod.com/sitebuildercontent/sitebuilderpictures/.pond/weedeaterflexkit2.jpg.w180h167.jpg]Mount Picture[/link]

RE: Poulan 25 from FL trimmer
 

Thanks for the info. I see it now. However my engine has some sort of plugs casted that can be used for mount. I drilled and tapped 6-32 hole in each plug and I will use them for custom stand-off plate. MVVS 1.6 is mounted using four 4mm screws (designed by MVVS) so I figured out 6-32 should be OK too. I left old fuel tank mounts just in case but if my four screw mount will work I can cut them off.

I have the carb with me. It is ZAMA with C1U casted in the body and on the side I see printed ID:
W18
38A

Can I run it, or do I need something bigger?

It has plastic choke lever, prime bulb and two screws for mixture (Low and High). By the way, choke has three positions: Full Choke, Half Choke, and Run. There was an air filter that I scraped.

The muffler looks very restrictive and heavy (6.5 oz). I'm going to order custom one. As for the prop adapter tis engine has piece of rod screved n the shaft holding the magneto wheel. I didn't measure the thread, but I'm going to turn something on my lathe (saving some money).

See the pictiure of the engine already cut. This engine has a hole (for the pump in carburator) below intake port but it does not have hole above the exhaust (like homie 25). Can anyone tell me what muffler I can get for that port?

RysiuM

RE: Poulan 25 from FL trimmer
 

I guess I'm getting out of touch? This engine is completely different from the Weed Eater 21 type engine. I see what you are talking about on the mount.

The muffler pattern doesn't match any I've seen.

Enjoy,

Jim

RE: Poulan 25 from FL trimmer
 

Tell us more about the piece of equipment this engine came out of. I've never seen this configuration before.

RE: Poulan 25 from FL trimmer
 

This one I got on e-bay from guys "theplacenashvill" (BTW very good responsive seller - item shipped the same day I paid). It is described as "NEW 25CC WEEDEATER BRAND 2 CYCLE GAS ENGINE. BOUGHT DIRECTLY FROM POULAN WEEDEATER". 25 bucks plus 10 shipping - not bad deal. It was entire weed eater head without the throttle linkage. They still have some on e-bay.

There are no marks on the green plastic case, but some symbols casted on the engine. Looking inside I see it is brand new but it has been run (something like test run) because I see burned oil on the exhaust port and on the ring. Short shaft (very short) has tapper for flywheel and short threaded part where the metal (steel) rod is screwed in. Thes steel rod holds the flywheel in place and has square hole on the other end (for weed wacker cable). The front part of the case has pull starter that engages two metal hooks on the front of the flywhel (easy to remove them).

The engine shown on the pictures (all ready to run with stock carburator minus muffler, prop adapter and back plate mounting) weights 3lb 1 oz. I beleive ready to fly will be about 3.5 lb (3lb 8 oz).
Flywheel and magneto assembly (including high voltage wire and plug cup) is a little over 1 lb. So converting it to CDI igniton would make it weight less than 3lb (including ignition module and battery) but would cost 145 dollars more (CH ignition). It still would make quite light 25cc engine for about 225 bucks (including custom muffler and new carburator).

Questions for all:

1. What type of carburator will fit without using the original plastic extension (with the extension the engine is to wide (it will not fit in my cowling now)

2. What is the thread on the shaft (I believe it is the same as any other 25cc weed wacker)

RysiuM

RE: Poulan 25 from FL trimmer
 

Hi RysiuM,
The shaft is 5/16x24. The hub and mount can be purchased from wackerengines.com or from them on ebay at reasonable price. You will need a insulator between the carb and the cylinder to keep the carb cool. You could cut the insulator down at the carb end and use shorter carb mount screws. This would make a narrower engine, but the carb will still stick out some. The Ryobi 31cc is the best narrow weedie conversion and it will be more powerful at the cost of about a pound in weight. The stock carb is best unless you enlarge the ports and advance the timing. The port size and time are very conservative for emissions purposes. Wacker can also provide a muffler or a complete conversion kit to save a little. It should make a good engine for a floater like a Cub etc.

Dave

RE: Poulan 25 from FL trimmer
 

Thanks Dave for the info. I want to save as much money as I can and make my own parts if possible. I can turn the hub on my lathe - I believe 6061 is used for that. This way I can have exactly the size I want. :)

All I need is to make sure that all parts (muffler, and carburator) are sticking no more than 4.5 inches from the center of the engine. My radial cowling is 9 inch diameter.

This 25cc engine is fine as it is very short and I have very short nose (I mean the plane has very short nose:D).

Did you mean as long as instead of unless ?

What is the port? I see my carburator has hole about 12mm at the engine side (where the butterfly is) and about 7mm at the venturi.

I'm still confused what type of carb I can use.

RysiuM

RE: Poulan 25 from FL trimmer
 

I'm attaching pictures of the carb that came with the engine and the picture of carb spacer.

Notice that spacer on the carburator side has a channel leading the air for the pumb and the rubber seal on the engine side. The spacer is about 1 inch thick - I would like it to be no more than 1/4 inch thick.

RysiuM

RE: Poulan 25 from FL trimmer
 

I just found this PDF at the internet. It it my trimmer.:D The original PDF is in the place:

[link=http://dixiesales.com/ipl/278/XT260.pdf]http://dixiesales.com/ipl/278/XT260.pdf[/link]

RysiuM

RE: Poulan 25 from FL trimmer
 

The carb appears to have no mixture adjusting screws? They would be side by side in the area where the two holes are in your last picture?

A model engine does not work without adjusting screws for the mixture.

You can get a good carb from Wacker?

Enjoy,

Jim

RE: Poulan 25 from FL trimmer
 

They are there. See the picture below. And the cast has marking L and H for low and high end. The screws ae the weird type as they are not for simple screwdriver but for some kind of tool (tube with goves inside). There is a metal guide so it is easier to fit this special wrench to screws while engine is running but it is useless for me as the screws are from the front of the engine just behind the prop. Now way to adjust carb while engine is running.

I noticed that my Brison 2.4 also has some kind of insulator/spacer between carburator and the engine. Maybe I just keep mine too :D

As for the prop hub I decided to turn my own from 6061 T6 Aluminum but to get better bite for engine shaft and prop screw I will use this piece used in automotive for broken thread in the engine block (I forgot the name of that - it is kind of steel spring that make the thread). The thread is 5/16 fine and I figured out that 30mm between prop hub and the flywheel is enough. I will show pictures when I'm done with that.

Now, the last question:

Will Wacker muffler for Homelite work for my engine? I don't know the shape of exhaust port of homi 25 so I don't know if the muffler can be the same. The distance between screws is 1-1/4 inch.

RysiuM

RE: Poulan 25 from FL trimmer
 

Rysium,,, Mighty fine camera work ! What camera are you using ?

RE: Poulan 25 from FL trimmer
 

I have to throw in my two cents worth about the POULAN 25cc FEATHERLITE engine. I have 105, ten to fifteen minute, flights on this engine. It uses a stock carb and 16x8 prop. Using it on a BUSA 120 Stingray. Easy starts no flameouts. Enough power to do all basic maneuvers. GREAT engine!!

RE: Poulan 25 from FL trimmer
 

Thanks.:) It's Canon EOS Rebel Digital (6M-pixel standard lenses). Came with Adobe PhotoShop Elements 2.0.

What muffler do you use? I saw on Wacker's page ([link=http://prophub.tripod.com/]http://prophub.tripod.com/[/link]) parts for Weedeater FL EX and Poulan engines that should fit mine.
http://prophub.tripod.com/sitebuilde...g.w180h167.jpg

He also shows the price for:
Muffler (bolt on stype ) $25
but no picture of that. Is it the same type muffler like shown on this picture?
http://prophub.tripod.com/sitebuilde...g.w180h235.jpg

RysiuM

RE: Poulan 25 from FL trimmer
 

Hi,
The weed eater brand engines use an offset bolt pattern for their bolt on mufflers, which is different from others. Wacker can make a muffler for you. If you have a short nose, the weight of the stock muffler might not be a concern. With a radial cowl of 9" the carb insulator souldn't be an issue. The engine will run better with the stock lenght intake. The stock muffler can be opened and baffles removed to releive back pressure. The threaded tubes used to attach bulb sockets to lamps can be used for bolt on exhust stacks. Engines ports are the openings into the cylinder. these are opened and closed by the moving piston. Intake is controlled by the piston skirt. Exhust and bypass/transfer ports are controlled by the piston crown. Port timing is the number of degrees before top dead center or after bottom dead center that the ports start to open. Port duration is how long that they stay open. If you are not up to speed on this you shoul leave them alone. From the pictures in the thread you can see how to make a simple mount using two spacers and four flathead machine screws. When you make the hub it is very import to have it true. Any offset of the prop shast will cause vibration and can cause a failure or injury. Such a large cowl indicate a large plane. How big is it? The 25cc may not ne enough power. Larger cowls usually need bigger props and thus larger engines.

Dave

RE: Poulan 25 from FL trimmer
 

Oh, yes. I know that. I run the tolerance about 0.01mm (or less than 0.001inch). I changed a little the design I saw here just to make sure I have everything true centered. And I didn't feel comfortable running the screw through the hub thread every time I change the prop (I didn't use helicoil as I couldn't find insert long enough).

So my design is that I have 12mm diameter hub extended as a prop shaft (it goes 17mm from the hub). The center is threaed and I have fixed (locite) 5/16-24 high grade steel screw. I will mount the prop on 12mm diameter shaft and the 5/16-24 nut with custom washer will be used to secure the prop on the hub. This way to change the prop I will remove the nut running on high grade steel thread.

See images below (I don't have a custom washer yet).

As the prop shaft (this 12mm diameter part) is in fact a part of the hub so it will run 100% true (+/- 0.01mm) The hub weights 1.4 oz but as you wrote, I don't need to worry about a little extra weight.:D

It's PZL 104 Wilga 35/80 about 23% scale (98 inch wingspan). The wing area is about 1000 inches and the expected weight should be 12 - 15 lb. It is scratch built from the plans I bought in UK. I had to shrink plans to 90% otherwise the plane wouldn't fit in my truck:D. With the size I have now the fuselage length is 69 inches (from the spinner to the rudder) so It will fit in 6ft bed.

RysiuM

RE: Poulan 25 from FL trimmer
 

I call of the day today. Prop washer is done. It is 7mm thick and has 5.5mm hole deep 12 mm ID and the rest is 8mm ID. The washer goes over the shaft (the part of the hub) leaving about 12 mm space between hub and washer. My props are 15mm thick so It is OK. I even found aluminum prop nut (I got it long time ago) that has 5/16-24 thread. Fits just fine.

Pictures here.

RysiuM

RE: Poulan 25 from FL trimmer
 

Nice looking setup............

RE: Poulan 25 from FL trimmer
 

What amazes me is that the engine without flywheel and magneto weights 2 lb (when the magneto support is cut off). It is the same weight as high priced brand name gasser of that size. All for 25 bucks. Adding electronic ignition (like CH with synchro-spark) for 145 bucks makes brand name like engine for less than half of brand name price:D. Use cheapper ignition and it goes even for less. I like conversion:)

RysiuM

RE: Poulan 25 from FL trimmer
 

A little correction to the prop size. The wooden prop I have are 15mm thick however yesterday I bought scale looking Master Airscrew 16x8 (clasic series) and this one is 19mm thick - 2mm thicker than the length of the aliminum part of the shaft. So I made another washer. This one is only 3mm thick and has 8mm hole.
I rimmed the prop to 12mm and it can be done leaving enough meat for support. Works just fine.

Yesterday I ordered muffler form Wacker. I hope it will come when I have mount ready.

Also I measured the distance of all the engine parts from the shaft to see how would it fit inside 9 inch round cowling. The farthest part is the spark plug and cup - about 6 inches. I will have to make a cut for that.
Next is the carburator. The farthest corner is 4.3 inch from the center of the shaft, so I should be fine. I will have to cut and modify choke lever as it sticks outside.
I don't know whe muffler yet but I'm sure I will need to cut at least the exit for exhaust pipes.

I also figured out how to make the throttle connection (the throttle arm is in front of the engine. I can use the part of carb spacer as a support for the bell crank that will direct the throttle linkage straight through the firewall. Quite clean solution.

RysiuM

RE: Poulan 25 from FL trimmer
 

The engine mount is done. I used my threaded holes for that. The aluminum plate is screwed through 8mm OD posts (three are 15mm long, and one is 13mm long) creating 3mm space between back plate and the mount. I will post pictures soon.

Right now the entire engine (without muffler) with 16x8 MA prop and the prop nut weights 3lb 8 oz. Right on the spot. As for now the entire cost was 25 for the engine +10 for shipping, 11 for the prop, 25 for the muffler + 3 for shipping. This thing is the cheapest engine I ever bought:D


RysiuM

RE: Poulan 25 from FL trimmer
 

When I receive the muffler from Wacker my engine will be ready to go on the plane. I didn't run it yet as I need to make some kind of test stand (I don't have a plane yet). However I removed the spark plug and I tried to flip the prop like I would start it. I've seen quite nice spark. It looks like I will be able to start it by hand flipping the prop. I think I still can reduce the gap between magneto and flywheel a little to get even stronger spark

Anyone knows, if this engine can run bigger with MA prop? Maybe something like Master Airscrew 18x6 ot 18x8 Classic Propeller ?

RysiuM

RE: Poulan 25 from FL trimmer
 

You picked the wrong motor if you need to swing an eighteen inch prop. I ran mine for the first time yesterday. Stock carb and muffler swinging a MA 16x6 got 6330rpm. The carb is lean on the low speed needle so you have to accelerate slowly until it gets warmed up. It does hand start easily though, full choke until you get a pop, then half choke until you get it running. I just got through running it with a G-23 carb, this got the rpm up to 7050. This motor doesn't have 10 minutes run time on it yet. I would imagine that a 16x8 prop will be about the limit if you want to make any useable power. I'm going to make a muffler for mine and try it with the larger carb.