Scota4570

I did a quick one with poor results. I am officially babysitting right now so I could not fuss around too much. For some reason the material wanted to crack. I may have to try annealing periodically with this stuff. Copper is easiar to work with. You get the idea though.

av8tor1977

My Feedback: (6)

Hey thanks for taking the time to photo document that process. Pretty neat! I am sure I will think of other uses for the process as time goes on as well.

Thanks again,
AV8TOR

Twin Star

I replaced the stock 9.53mm carb with an 11mm carb on my homie 30. I used the stock un-modified manifold and was surprised to loose 200 RPM off the top end. I expected some gain even if it wasn't much, but a loss that sucks.

Any body got any ideas why I lost power?

w8ye

My Feedback: (16)

They usually perform pretty good when you do this

Twin Star

I have other 11mm carbs, maybe the engine just doesn't like that one. It ran fine on my Poulan 32. Although My Poulan did seem to like the WT-258 a bit better than the WT-324. The same WT-324 I just tried on the Homie.

av8tor1977

My Feedback: (6)

The only thing I can think of that might cause this is extreme turbulence in the manifold reducing flow. The Homey 25/30cc really needs an 11mm carb to perform better, but if the carb exit throat is larger than the manifold entry, there will be a lip of the manifold sticking into the airstream that could easily cause a net drop in airflow. Measure, or use a gasket to verify carb exit and manifold entry sizes. The carb exit throats vary in size, even though the venturi itself may be 11mm.

AV8TOR

w8ye

My Feedback: (16)

I agree with Av8tor

Twin Star

I had already taken those measurements and found that the manifold dia. was 12.5mm and the exit port on the carb. was 15mm. I knew this situation was not ideal but I didn't feel it would have such a negative affect on performance.

I did notice that after I changed to the larger carb, fuel seemed to "drool" out my "high tech" intake stack at a high power setting. This could suggest, your theory could be true. If I enlarge the stock intake or purchase an large bore after market one, I will then have a size issue at the cyl. intake port. I'm not comfortable grinding on the cyl. ports as I have no experience at this.

P.S. I apparently have a newer homie 30, with what appers as a faceted intake port.

Twin Star

I started to change the carb to a different one and found that I likely had a vacuum leak because the gasket I had didn't line up properly. Made a new gasket and put on the same carb to keep things consistent. I got my 200 RPMs back but that was it. No increase in RPM going from the 9.53 to the 11mm. I'm still at 6900.

azalner

My Feedback: (8)

This thread interests me as well. I am in the process of converting a 30 cc Homie and purchased a WT542 carb for it. I took some measurements and found that the inlet manifold diameter is 12.98 mm and the throat of the carburetor is 15.81 mm. Seems to me that this will result in a restriction of the fuel/air mixture. Any suggestions? What options do I have in order to get the most from this carb?

AlZ

av8tor1977

My Feedback: (6)

See post number 5 is this same thread....

AV8TOR

Twin Star

When you port the intake manifold and you port the cyl to match the intake do you also enlarge the port opening at the cyl wall?
Or is that better left alone.

av8tor1977

My Feedback: (6)

In most cases I would just leave the actual port opening into the cylinder alone. Just massage the port area near the inlet to match the new manifold size/shape.

AV8TOR

Twin Star

I can only get 6900 RPMs with stock carb, gutted muffler and 17/8 prop. After trying two different 11mm carbs on my Homie 30 It still gets 6900.

I am starting to get the feeling that the small stock intake is the limiting factor.

What is the general opinion?

av8tor1977

My Feedback: (6)

Did you ever check your ring gap as I had mentioned before? All modification programs should start with a fresh engine in perfect shape to begin with...

Yes, you need to enlarge the intake for best results...

AV8TOR

Twin Star

No, I am trying bolt items to see how close I can get to my goal of 7500 w/ 17x8. My thinking is if I get real close to my goal, the rings should be the icing on the cake. But maybe my thinking is backward[sm=50_50.gif] Plus I don't like re-opening after putting in new rings, not sure why, but to me, it doesn't seem like a good idea. I do however know the leak-down is a bit high, indicating wide ring gap and/or tired rings, also a factor for the less than great power.

Twin Star

I may have found part, of the reason my Homie 30 performance isn't meeting my expectation. I pulled the jug off to check the ring gap as well as cyl. condition and found the transfer ports were at least 65% blocked by the cyl. gasket

av8tor1977

My Feedback: (6)

Well, that certainly wasn't helping...

How's the ring gap? It should be .003". (That's about the thickness of a sheet of paper.)

AV8TOR

Twin Star

I didn't have a good feeler gage at the time but it was at least .0010 - .0015 best I could tell. I did find, the upper ring at one end was stuck at the pin. There was allot of carbon behind the ring too. I cleaned both the grooves and things look good now. Put it back together and it seem the leak-down got worse instead of better but maybe after it is run it will get better.

w8ye

My Feedback: (16)

You can get new rings from Frank Bowman if you need them [email protected]

Twin Star

I am going to replace the rings later and and I will certainly use Frank's rings.

I ran the engine after un-sticking the ring it still runs 6900. I was hoping for some increase but I guess it would be kinda like a new ring now, it will probably have to re-seat. Now after taking the top end off and seeing the cyl. gasket covering the ports by 65% I cut the gasket back but then noticed the crankcase was the same way.

How much performance could I expect if I were to match the crankcase to the cyl. transfer ports. I just feel there has to be a bottle neck somewhere. The rings can't be the only performance increace to be still had.

w8ye

My Feedback: (16)

In matching the transfers, maybe a little blending on the cylinder as well as the crankcase?

av8tor1977

My Feedback: (6)

Check the exhaust timing. If it is 140 degrees plus, you're ok. (I like 150 for the rpms you're looking to run.) You might find it down around 120, which really limits power.

Also, I don't remember what muffler you are running, but it should have virtually no baffling inside, and two outlets of 1/2" i.d. minimum. Larger is better.

AV8TOR

Twin Star

I did a check on the exhaust timing on my Homie 30. I got 125 degrees. From what I've gathered from the posts that isn't to good.

Of course that leads me to the obvious question, What can I do about it?

Current config. gutted stock muffler with one 1/2" outlet and stock 9.53mm carb. 17 x 8 prop. 6900 RPMs

av8tor1977

My Feedback: (6)

I give up....

AV8TOR