KI8FR

I have a homie that I did.. all I did to this one is cut the front off and put on a S/S ignition. on it.. I have the stock carb on it. I have a 16x8 prop and I am geting 6400 rpms out of it.. Is that about all Im going to get with this engine the way i have it set up?

Paul

Ralphbf

My Feedback: (27)

What size is it?
What did it come out of?
What model number is it?
What is the compression like?
At what degree does the ignition fire?
Do you get more RPM the more throttle you give it or does it bog down at higher throttle?

KI8FR

[quote]ORIGINAL: Ralphbf

What size is it?

It is a 25cc

What did it come out of?

weed eater

What model number is it?

No idea

What is the compression like?

very good compression....

At what degree does the ignition fire?

30 degrees

Do you get more RPM the more throttle you give it or does it bog down at higher throttle?

No it does not bog down but at 3/4 throttle to full the rpms will stay the same.. I know that is one thing that is not right.... I do not know but I think the carb is just to small I do not know

I hope this info helps

av8tor1977

My Feedback: (6)

Something is not right, as it should do at least 1000 rpms more with that prop. One thing is it is going to need a larger carb.

Take the muffler off and try it and see what happens. (Prepare yourself, it's going to be really loud....) Before you run it, look into the port and see if it is plugged with carbon.

AV8TOR

KI8FR

Muffler I did not think of that.. the muffler is one that I made and It just mite be to small of a hole in it.... The engine was just cleend out and there is no carbon in it at all.. I will pull off the muffler and see what I get out of it..

Paul

Ralphbf

My Feedback: (27)

I believe 7500 would be a reasonable RPM although a 16 x 8 prop
would be the largest prop you could run. You might try a 15 x 8.
Also the engine will gain about 300 RPM in the air

Another thing to try is remove the screen from the mufflers outlet.
This will give you more flow and should not cause the engine to go lean at higher RPM.

I assume the Carb. has limiters on the needles. And you may only have one needle.
If this is so you will need a different carb. Or someone else can tell you how to modify this Carb.

Was the shaft on the String Trimmer bent or straight?

A picture would be nice. Some of the guys can tell what you have just by looking.

Keep us posted

av8tor1977

My Feedback: (6)

I run two 7/16" outlets on my mufflers for engines this size.

I always hop my engines up at least a little bit, but the Homelite 25cc should run close to 8000 rpms with an APC 16 x 8 prop even with minimal mods if everything is right. For sure 7500 plus...

AV8TOR

KI8FR

I took the mufler off and got 7500 so I know that has to be it..... that is with the small carb on it.. I have a wolbro with a 28 on it I will put that on and see how it will do.. Thanks all

davewallace

My Feedback: (29)

k18fr,
The "28" Walbro has an 11mm venturi and usually has a 5/8ths inch throttle bore, which is larger then the stock 1/2' hole in the insulator. The next step after the 11mm carb would be to bore out the insulator to 5/8ths inch and add an external pulse hose to drive the carb pump.

Dave

av8tor1977

My Feedback: (6)

Be careful "boring" the carb adapter/insulator out. Most people think right away of drilling it out, and usually the drill catches in the soft material and ruins the adapter. I use a sanding drum in a Dremel to open them up. Make sure you don't leave a lip where the manifold mates with the cylinder as that can disturb flow....

AV8TOR

KI8FR

Im not going to do that to this one yet, untill I see if it is my muffler.. I think it is cuz when I bring up the throttle to 1/2 I get 6400 and when I get to full throttle I get 6400 I know the muffler will do that.... lol I just did not think of that..

that sucks when that happens

w8ye

My Feedback: (16)

The stock carb is a "20" and is 5/16" venturi. Or 7.9375mm

The most desirable "28" carburetor is 7/16" venturi. Or 11.11 mm

A "32" carb would be a 1/2" carburetor. The "32" is too large for a 25cc Homelite unless you are running 11,000 or so rpm

My absolutely stock except for muffler Homelite 25 turned a Dynaflite 16-10 at 7,000 rpm

My stock Homelite 30cc with a 28 carb and Abel muffler turns 7500 with a DynaFlite 18-8

My modified Homelite 30 with a "27" carb turns 8200 with a MAS 18-8

av8tor1977

My Feedback: (6)

He was talking about the throttle bore at the manifold interface, and the manifold, (carb adapter), not the venturi. He specified a "28", or 11mm venturi carb....

AV8TOR

w8ye

My Feedback: (16)

OK I see now. Not trying to start anything, but . . . .

You can have several different sizes of throttle plate bores and still have a 8 or 11mm venturi carburetor

Throttle bore dimensions are not an exacting measurement of the performance of a carburetor

One nice thing about the popular WA167A Walbro is that it has a relatively small throttle plate bore compared to some 11mm carburetors. The standard Homelite 25 carburetor insulator is readily able to accommodate enlarging to fit this carburetor.

KI8FR

I got it working good now.. changed the mufler and now I get 74 to 7700.. That is good # what what Im going to do with it... Thanks all
Paul