spaceworm

Yeah, the hot start problem was what I said; I guess the reference to the Corvair turned all the Yunguns off and they did not read further. Anyway, G10 glass epoxy laminate will also work well for a carb insulator. I have stacked and epoxied together .062 pc board material to get the thicknesss I needed. An easy fix. For those needing to rotate a carb to get the linkage in line with the servo rod, the pulse passage can be built into the interior laminates of a G10 stack so it enters on the engine side and exits on the carb side wherever you want it. Of course, you do this before you epoxy the stack together.

Regards,

Richard

av8tor1977

My Feedback: (6)

Well that's an interesting way to handle a pulse hole problem. (Your laminate) I always just run an external pulse if the original setup doesn't work for how I want to set things up. Also, many times I enlarge the carb spacer throat and it either gets into, or very close to the pulse passage. I just JB Weld it shut and do external.

AV8TOR

rotccapt

well guys i think my problems are solved. i did several of the ideas posted here. i took the engine off the plane and mounted it to my test stand so that it would be easier to work on. i took and richend up the low end, added a carb spacer that i made out of 1/4" hard wood for now phenolic will come later. also i took off my scale muffler and just left an open pipe no muffler at all just for giggles so i have no restriction at all, also i added a throttle curve. i just started it up and once i got fuel to the carb it started within a couple seconds of rotation. i ran it up and it was a very smooth transition. now i can snap open the throttle and it will not stumble. i will add back in my scale muffler tomorrow and do some more tweaking. any ideas on how to set up a choke on this engine? it would mostly just be used to get fuel to the carb faster when the lines are empty. also where is a good place to get 1/4" phenolic?

after shutting down the engine i decided to try and start it up again and it started as soon as it passed compression so i think my spacer did the trick. i will try to get some numbers tomorrow to see if my modded did anything to the performance if not i may try playing with timing to see if i can get back to where i was with the glow carb which was 8500 rpm

anyone know a good place to get phenolic in about a 1/4" thickness?

w8ye

My Feedback: (16)

McMaster-Carr (330) 342-6100. [email protected]
(330) 995-5500
(330) 342-3330


http://www.mcmaster.com/#phenolic-sheets/=6ldocq

rotccapt

thanks for the link i ordered a 12x12x.25 sheet they say it will ship Monday so i,m hopping to get it by the end of the week. my plan is to cut it with my scroll saw will this work ok? also i will be cutting it in the oval shape like most carb gaskets are to save weight. to cut the hole for the intake i will be using a drill press and a spade bit or maybe a forsner bit if i decided to go buy one then clean up the edges with a sanding drum in my dremel

w8ye

My Feedback: (16)

I've cut a lot of it with a DoAll band saw. It should cut well with a scroll saw.

It is readily machinable. You will like it.

rotccapt

cool thanks not what to do with the rest of the sheet? it sounds like a good material for servo trays and what not

spaceworm

Although I make mine typically out of glass epoxy pc board material, there are likely lots of gassers out there that need a piece of that material, for applications like yours. Figure out your selling price and suggest interested people to contact you by PM for purchase. You can make a lot of 2 inch by 2 inch pieces out of a 12 by 12 square, and mail it for a first class stamp or minimal postage.

rotccapt

well i haven't ran it yet but i think i figured out why i am down on rpm from when i ran it on the glow carb. i decided to make a new sensor mount and i did not re set the timing with a degree wheel i just eye balled it to where my sensor was mounted. i just checked it and i was sparking at almost 50 degrees BTDC so i have set up the sensor at 28 degrees but i zip tied it there so that i can move it while the engine is running (yes i will be careful when i do) this way i can find the optimum timing and then drill new mount holes. with my timing being off i can only imagine why i was low on power. i ran in to this when i put the ignition on the first time and i picked up 2000 rpm by just adjusting timing

PlaneKrazee

My Feedback: (14)

UAV guys did this with Enya 155 four strokes using a series of check valves.

rotccapt

well i just got done running it and i have to say i pick up a few rpm but my tach is defunked so i will have to get a new one. i did a 10 minuet run with it today at full throttle and it burned a little over 4 oz of fuel so with my 8 oz tank i will have almost 20 minuets of flight time. also with the timing reset it will now hand start using my chicken stick. also after that run the carb stayed cool to the touch.

rotccapt

well i got it reinstalled on the plane after making my new carb spacer and i got some static thrust numbers. i am getting 8.2 lbs of thrust off my current setup. i know this engine can do better and i dont realy feal comfortable flying an 11 lb plane with 8 lbs of thrust i know i would be ok, but i like to have get outa trouble power and at those numbers i dont have it. so i decided to order a wt-456-1 to see if i get a bit more performance out of the engine. i know that when i ran the glow carb i was getting 8600rpm so right now i am almost 1000 rpm slow. so hopefully i can get my power back.

pullup can you post a pic of your counter spring that you installed to help the servo? also would it be possible to use the throttle shaft that is on my wt-340 in the 456? i ask this because i soldered a ball link to the throttle arm to attach my linkage to and it would be nice to re use it. i know i can just de solder it but if that is not required it would be nice. other than this my plane is ready to fly

CH Ignitions

My Feedback: (11)

I gust started today my FG20 with wt 456-1 use a master airscrew 16x8 . I had a heal of a time to prime the carby. I finaly started. I am getting only 7800 RPM and idle around 2500RPM. I full with all evening . Tomorrow I will play more with it.
Ican say it runs fine ...but I still not like that top RPM. I wish I can get more. I will try to take a video tomorrow if I get time. Now are any repair inserts for 1/4 32? I guess I will need one soon.

Thank you
Adrian

Pull Up Now!

My Feedback: (3)

It's been a while since I've been on this forum. Been too busy flying....so I might have missed this somewhere in this thread, but i7x58, WHY are you adapting a different gas carb onto an engine (FG20) that is ALREADY a gas ignition engine?

Pull Up Now!

My Feedback: (3)

No reason you can't adapt the throttle plate to the new carb. As with most such thing, some adapting might be necessary. You will have to be the judge as to whether any adaptation is more work than just resoldering the ball link onto the WT456.

8lbs of static thrust is plenty for an 11 lb model. Unless it's for 3D.

I'll try to post the pics of the counter-spring this weekend. Sorry it took so much time to answer your request. Somehow, my subscription (gives email warnings) lapsed on this thread, so I just thought it was quiet here.

CH Ignitions

My Feedback: (11)

Well,
I did it for all those that complain about it on the FG 20 thread that have problems with carburation and for those with FA125 that will want to convert to gas. It can be done and it works. It was just a thing to see if I can do it.To get mine mind of off the fact that my wife left, to get me a reason of tomorrow.

Thank You
Adrian

rotccapt

i7x58 what are your needle settings on your engine? also you might want to re route your fuel line you may melt the tygon fuel line the way it is it looks like it is resting on the head. i took that barbed fitting off so that the line gose strait into the carb

pull up no problem i figured it out but now the engine will not start i got it to run for a few seconds at idle but when i tried to advance the throttle it died. i need to play with it some more but have not had the time.

Pull Up Now!

My Feedback: (3)

I had no idea the FG20 was anything other than great. Surprised to hear of stock engine carb problems. BUT....I had one in my hands at the LHS and commented that the carb looked so small, and wondered how they accomplished the pump and regulator in such a small carb. In other words, I was doubtful it would work well. First instincts correct I guess.

Sorry about the wife! Keep cool and stay focused!

Pull Up Now!

My Feedback: (3)

Just curious, where did you order your WT456? I ordered from a local lawn shop, and it took about 1 1/2 months to get. Very irritating. Meanwhile, I ordered a couple from a guy on Ebay and they came in a couple days, for lower cost.

CH Ignitions

My Feedback: (11)

Lot of people complain about the original carb with setings that work on the ground and not on the air and that is hard to adjust, Second version carb (with a dot) it is better.
Igot the Carb on Ebay from Captain Never Sails ( Carl) and it come in couple days.

Adrian

spaceworm

[/quote]

"I'll try to post the pics of the counter-spring this weekend. "

[/quote]


Hi. Is the "counter-spring" you refer to use to counter the existing throttle return spring? I just slip or snip the little hook off of the stock return spring and leave it in place to act as a spacer. Pros and cons of each approach?? TIA

w8ye

My Feedback: (16)

I didn't search up above for the specifics but . . . .

In this thread and talking about the Walbro WT-456, it has a spring on the pressure signal side of the pump diaphragm to push the fuel out of the pump. The diaphragm works from a vacuum impulse only. The spring serves as the pressure impulse.

This spring is used on four stroke engine so the carb will work with a impulse signal from the intake manifold only.

All the Saito gas carbs on the FG-14, FG-20, FG-30, and FG-36 from the factory work this way.

The Walbro WT-456 was a OEM carb on a Ryobi Four Stroke weed whacker engine

Other Walbro carbs can be modified for the pump to work like the Walbro WT-456 by machining a spring seat in the pump cover and adding the spring

CH Ignitions

My Feedback: (11)

Well,
today I play more with the setup. FG20 Walbro 456-1 Evolution 16x6
3/4 turn on Idle and 1 1/2 Hihg will give me a 2400 idle RPM's. top RPM I got 8550.
But not with the above H+L setup. If I get good Low I can't get the High rpm's. Something is not quite right. Iread the Walbro setup adjustment for WT. And I can't get it by the way they say.
OK, I get on low Screw in to lower rpm's but I have to open the H neddle. it stay on Idle but not solid ramps up,down. when I want to throtlle it dies.and will not start easy.
To get top Rpm's set the low 1 1/4- 1/2 and high 1 1/3/4 it will get the tops, nice transition no stumble. But it Idle around 34-3500, if I lean out then stumble and dies.

I do have the feeling that carby does not get enough gas. I can't figure out. The pump membrane is the black one, is that to stiff? When I go onhigh rpm's it runs and then feel like it ....dies like it starves for gas.the pulse tubing is 1/8 tubing bought from hobby shop. When running I pull the Tygon off and it stops.

Also on the first start when is empty line, will not pull fuel. I pull the fuel, pinch the line than I plug in to carby. After that I start crancking with the spinner. Not good enough, I loose the middle screw from the pump and let some fuel to come off there . After that it starts. After is hot is starting up, carby does not get hot,stay cool at the touch. I do have another carby, WA 120, I am thinking to give that one a try . I will steal the pumping plate with the spring and put it on that one.In theory it should work.

Any Ideeas, sugestions?

Thank you
Adrian

spaceworm

Boy was I way off base. Thanks for your response. I understand the negative pulse and the spring. Where do you get this spring? is it available from Walbro, and is there only one part number? Thanks again.

w8ye

My Feedback: (16)

http://www.outdoor-equipment-parts.c...?isbn=CA983226

A cover already machined is listed at M&D as
(Just click on the part number)

<input type="hidden" value="WL-21-3198-1" name="mv_order_item" /> WL-21-3198-1	<input type="hidden" value="WL-21-3198-1" name="mv_order_item" />	2131981/21-3198-1 WALBRO CARBURETOR PART 2131981/21-3198-1 Cover-fuel pump	$2.54

WL-98-3226

<input type="hidden" value="WL-98-3226" name="mv_order_item" />

983226/98-3226 WALBRO CARBURETOR PART 983226/98-3226 Spring

$0.75