I have an Homelite 25cc weed wacker. I would like to use the engine in an airplane. Has anyone ever converted such an engine ie: engine mount, muffler, prop adapter? Any help would be greatly appreciated!!!

Do search here on the 25cc homelite.lotta people have converted them and they work great.,,,,,,,For conversion parts go to

wackerengines.com

Thanks much, Slade_LoD, I did go on their site (well, before Frances hit them in Florida as I can't connect to their site anymore) and I did see what I needed.

Again, thanks!

I finally recieved my prop adapter, etc from wackerengines.com and everything fits fine.
I ran the engine with an APC 15 x 7 prop and I am getting 8500 RPM top speed. Alas, I can't get the engine to idle under 4300 RPM.
Heck, you can't land at that speed. Anyone know how to lower the idle on such an engine? It has a Zama carburator and both high speed and low speed screws are capped so not to be adjusted. The butterfly does close fully.

Any hints please?

Check to be sure the idle stop screw has been completely backed out. I don't know what model of Zama it has, but I have one from another engine that I won't ever use (changed engines) and the needles are adjustable. Send a PM if you may want it.

Pat

Many people have done this.
I would recommend contacting RCIGN1.

Sorry but who or what is RCIGN1?

I may look dumb but who or what is RCIGN1?

Hi! I don't know if this applies to your fast idle problem but I have found that several of the newer style Zama carbs have two holes in the throttle butterfly that are around 1/8 in dia. . This could and has caused a very fast Idle on some of my engines. I generally fix the problem by changing the carb. The best are the 2-needle Walbros and some of the Zamas work very well also........Bob

Hi jchoquette! If the problem is the hole (s) in the butterfly try to solder them that way you dont have to replace the carb, the other thing is try a bigger prop (16x8) usually APC props are the best performance wise, I think that a 15x7 is very small and not putting enough load on the engine, there are other tricks to make your engine get higher rpms at the high end of the throttle like making the venturi hole in the carb bigger (0.400 inch diameter) just make sure not to damage the bronze fitting sticking out cut around it you can use an xacto knife to churn off the aluminum until you reach the diameter desired; or simply go and buy a bigger carb for it.

If the caps you refer to are the 'don't tinker with me' plastic ones, slit their sides and pull them off. You may find that the H & L needles are in fact adjustable to improve the existing carbs operation.

Particularly liked the WHAT part of your question!
RCIGN is a frequent poster in this and other forums. 'Some have said he has probably forgotten more about engines than you and I will ever know....' Of course that is just hearsay....BUT I do read alot of his posts to threads to garner helpful tidbits of knowledge. Do a search and it will show his recent posts.

I would not solder a thing just replace it with a better carb that is my opinion.

you can put the air filter back on it and it will idle fine other wise I would get a good carb

I agree with Aeronut and the suggestion to solder up the hole in the throttle plate(if there is indeed one there to be soldered up).This is a cheap and easy fix compared to buying another carb.You should be able to kill the engine with your trim tabs if it is set up right.If your engine still runs with the throttle plate fully closed,you have an air leak some where.Your engines idle speed is controlled by your radio's trim tab setting,not the idle speed screw on the carb.This screw should be backed all the way out to allow the throttle to completetly close or remove it from the carb all together as it really has no purpose here anymore.The throttle arm return spring on the carb should also be deactivated so it is no longer spring loaded as this only adds extra load to the throttle servo and battery drain.Use side cutters and clip off the ends of the spring so they no longer engage anything.Do not remove the spring body though as it acts like a spacer for the throttle arm and keeps it from slopping all over the place.Hope this helps some.Happy flying.

Dont get me wrong, but it could be something wrong with the carb. But it could be also that engine may be old and has lost compression. Does the engine still have good compression?, Plus whens the last time you changed the spark plug?
Its true that an old spark plug that half worn out will not allow the engine to idle properly, and thus not letting the engine run any lower than 4300rpm for idle.
Also bad fuel. If you are running fuel that has been sitting in your shed or whatever that you use for your lawn mower or Weed Eater or whatever. And it has been sitting there in the can for couple of months. Then you should really go out and get a gallon of new fuel and pick up some new 2-stroke oil. You can be possibly running the engine WITHOUT enough oil in the fuel. Thus having the engine running 'eratic'. I mean theres a lot of things you need to check before you blame it on the carb.

I would first put new fuel in the tank, change the spark plug to a new one and fire up the engine again. Then TRY and work on the idle screw. Get the engine running on a low nice RPM idle. You should be hearing a nice 'rumble' idle.

Good Luck!

on some of the single needle carbs and needle free carbs do not seem to idle low once you remove the air cleaner . I have ran into this problem often but not always.

Apparently this ZAMA carb has both high and low speed needles (post #4). I'd start by removing the idle stop screw completely, closing any holes in the throttle butterfly, removing the plastic "don't tiinker with me" covers that are on the needles and disable the throttle arm return spring. Adjust the carb linkage to fully open and close the throttle. Make sure there are no leaks around the carb base and intake manifold. Having done all of these steps your ready to start testing too see what you've got and how it performs.

Antique: well put and he will not have spent any $$ and will have had a good learning experience on disposable carb.

aero nut's suggestions are good also.
Based on my homie25 and APC 16-8 16-10s, I would not hesitate to try a 18-6 as well for more thrust and engine loading. The additional air volume flow at lower rpm offsets the higher rpm. Load at idle seems to make it a little smoother idle.