That is a rather large carb for your engine

Yeah, I agree. It will most likely be very "finicky" and hard to live with using a carb that big. I would stick to an 11 mm carb, and preferably one with an accelerator pump if you can find one. (Not imperative that it have the pump, but it is nice.)

AV8TOR

I thought all walbro carb were "accelerator pump" carbs.

Please, do you guys know what carb model would be the best for me?
I'm pretty new to this convertion thing and I just don't know anything about carbs.

Thanks.
Moss.

All Walbro carbs have a fuel pump in them, but not all have an accelerator pump.

W8YE, could you re-post that list of 11mm carbs you have for him here?

AV8TOR

Here is a list from RCU in 2004 of both Walbro and Zama carbs with 11mm venturi:
http://www.rcuniverse.com/forum/Walb...2371019/tm.htm

Here is a more recent list posted by MOTORHD on RCU:

These are the rest of the WT Walbro carbs with accelorator pumps.

6.5 mm with fuel pump return spring (4 stroke) WT 366-1 WT 456-1

7.95mm WT 37-1 WT 424-1

9.53mm WT 35-1 WT 38-1 WT 204-1 WT 357-1 WT 367-1 WT 381-1 WT 385-1 WT 417-1 WT 449-1 WT 450-1

11.11 mm WT 29-1 WT 356-1 WT 358-1 WT 464-1 WT 516-1 WT 517-1 WT 527-1 WT 613-1

Here is the link to the last post:

http://www.rcuniverse.com/forum/m_9696397/tm.htm

WOW! thank you very much to all of you!

Av8tor, what is the diference between Pump carburator and accelerator pump?

Thanks
Moss.

The Walbro and Zama carbs are pump carburetors in that they have a built in fuel pump on one side and a demand type regulator on the other side.

Some of the Walbros also have an accelerator pump so that when you advance the throttle open, they squirt a little fuel into the engine to help the engine get going faster.

I wasn't the one with the list?

Oh, sorry. I thought it was you that posted a huge long list of 11mm carbs some time ago...

AV8TOR

I had no luck finding those accelerator carbs, but I found a nib wt-391, I hope it may fit my G90.

Now, if I decide to convert my G2300, wich one should I use?


Thanks
Moss

Dear all,

Yesterday, I got my G90 converted and hit the air.

my setup.
Supertigre G90, stock carb, perry pump, ignition, 13X7 prop.

On the ground I got an excelent high speed, poor transition and an acceptable idle speed,
first flight and it were ok for first 5 minutes on full throtle them it started to lean but never died.
opened high speed needle two click and it got perfect for next 4 minutes, and all happend again.
on the ground again, I closed the low speed needle about 1/8 turn, better transition, but a poor idle.

Some guys at the field said it could be the sensor position, what is yours thought? should I advance it or retard it?

Moss

Dear all,

I just got a new WT391 walbro carb. Now I have some questions.

1) it has two brass nipple, one close to the LOW/High needles and another on the oposite
side. So, wich one is the gas intaken? What is the other nipple for?

2) on the botton side, the side where I will attach the adapter, there are two small holes
one each side the venturi. one of them is blind, on the other, there is a very tight hole,
is there any problem if I close it with the adapter or do I need to do something about this
small tight passage?

3) Does this carb uses any connection to the engine pressure, ir order to make the carb pump work?

that second hole you note in point 2 is the pulse port of the engine, you can block it off if you plan to tap a pulse port in the pump cover but the carburetor needs a crank pulse from somewhere.

I don't know about question 1 without a carb in my hand...

You will typically find that the nipple closer to the needle valves is smaller than the other one. The nipple closest to the needle valves was originally the purge port that went to a little squeeze bulb pump to suck fuel through the carb to eliminate air. This one will suck air if left open. It must be closed off

The other nipple on the opposite side is the fuel input nipple<div style="overflow: hidden; color: rgb(0, 0, 0); background-color: transparent; text-align: left; text-decoration: none; border: medium none;"></div>

Does anyone has a schematics for the adapter?

rangerfredbob, I intent to keed the carb as original as possible, so, Do I need to let it open to the air or conect it to somewhere?
Does anyone has pisctures of such adapter and convertion?

W8YE, thank you!

HI, Posted some new pictures of my work on my Echo 61cc twin. made a muffler for it, still need to get it powder coated. I am having a problem trying to figure how to make a mount for thepick up and where to locate it. Any suggestions anyone? Pictures located in my gallery.

The grass is starting to grow. Hopfuly that will mean the conversion forum will light up again due to the fresh batch of power equipment in need of work.

The only thing I have converted lately...was from outside work..to sitting on the couch looking outside at that rotten cold grey day..

I fairly recently finished up another BME twin. I used 25cc crankshafts on this one, and hopped it up. It turns over 8000 on a 20 x 8, and that after only two tanks of running.

I am presently working on another Homelite 30cc. I am toning this one down a touch as compared to my last one, so as to turn a larger prop. My last one turns an APC 16 x 8 at 9400 rpms, but kind of falls on it's face with an 18" prop. I had made the port timing, carb size, etc. fairly wild on that one. This new one I am doing will have a NOS cylinder that I bought several years ago that has considerably bigger transfer ports than normal for the Homelite 25/30cc engines, but I am going to stay fairly conservative on the port timing. I will use a Frank Bowman ring, stuff the crankcase, lowered cylinder and optimized deck height, etc. though. It will be interesting to see how it runs.

Then, someday this summer, I have one more BME twin block, one of the older square ones. I also have all the pieces of a 62cc Echo twin chainsaw. So, I am going to do another twin, this time a 62cc.

Then I have lots of other engines; Stihls, Echos, etc. to play with....

AV8TOR

Gas is going to be over 5 dollars a gallon here by Memorial Day. Forget the cost of flying, can't afford to get to the feild! Electric helicopters are looking better everday.

Row boats &amp; fishing is looking better better too! If you catch a fish...it puts food on the table! Capt,n

Whatever turns your rotor or floats your boat. RC is still cheaper than therapy or a divorce.[8D]

regards, Richard/Club SAITO #635

Its the cause of divorce occasionally.
People who expect to fly airplanes and not crash need therapy or at least that what my ex wife told me.