Diablo-RCU

My Feedback: (1)

Anyone know for sure if a Walbro carb will meter fuel if you remove the choke shaft and butterfly? I removed the choke on mine (for cowl clearance) and it won't run right above half throttle. I'm thinking that it's possible that the choke shaft provides more vacuum on the high speed needle port in the carb. Acts like the high speed circuit won't flow fuel. I've gone through the carb and put a rebuild kit in it. Still runs the same. It's a new engine that I didn't run before I removed the choke, so I can't compare the before and after. Pulse port is clear, gaskets sealed.

coony2787

My Feedback: (33)

I dont know but it seems like it wouldnt make a differnce since the walbro carbs are pumped. Just a thought [8D].


Chad

Diablo-RCU

My Feedback: (1)

Yes, they are pumped. But they won't flow any fuel unless vacuum pulls fuel out of the orifices, which then pulls on the metering diaphragm which then opens the needle off the seat.

Antique

My Feedback: (4)

I've pulled the choke plate & shaft out of a couple of mine and it made no difference in performance.

Geistware

My Feedback: (16)

Removing the choke will not make a difference.
With that said, if you adjusted your engine but the choke never opened up all the way, then removing the choke butterfly will make a big difference.

pe reivers

Removing the choke in general improoves matters, because the airflow in our model planes pretty much upsets things, mainly WOT response. My favourite Walbro has no choke
It is the venturi that provides the fuel draw by Bernoulli's law. Not the choke, which only aids in getting a very rich starting mixture. After that, the prop blast against the open choke plate only creates problems.

Diablo-RCU

My Feedback: (1)

OK. Guess I'll have to borrow a carb from a buddy to see if mine is duff.

Geistware

My Feedback: (16)

What you say is true, but if the choke is partically closed, it will cause more fuel to draw when the engine is running.
If you don't believe me, try it. I did once by mistake. To get it to run, I had to lean the carb. When I found the problem and corrected it, (servo didn't allow choke to open all the way) the engine was too lean and I had to richen it up.

majortom-RCU

My Feedback: (40)

So with the choke removed, how do you start it? With no cowl, you could stick your thumb down its throat, but with a cowl, what's the starting routine? Gasser newbies want to know!

pe reivers

Yep,
You also don't run cars with the choke partially drawn. Thank G*d the device now is automatic and needs no consumer input, or integrated in the fuel injection cirquittry.
I myself prefer turbo charged diesel engines: get the go without the woe.

pe reivers

As far as I know, there are two methods to choke without a choke.
1) construct a device that will push on the regulating membrane. This will allow the pump to inject fuel directly into the carb, even without choke. Just bumping the prop to and fro against compression will get the engine wet and hissing. I have successfully used some spring wire with a branch soldered onto it. In the steel cover I drilled a central hole to provide access to the diaphragm plate. The steel wire was secured under one of the cover corner screws. The push lever can be moved to a convenient location.
2) Add a fuel injection nipple to the crankcase, and use a syringe to inject 0.5cc of fuel directly into the cranckase. This works better than a choke, because now you know how much gas you spent that engine. This also works best in inverted applications, when most choked fuel just drips out of the carb again. (depending on carb position)

Diablo-RCU

My Feedback: (1)

Three more methods:
Squirt WD-40 into the carb.
Stick your thumb in the venturi while cranking the prop with other hand.
Blow into the tube connected to the diaphragm cover vent while rocking the prop back and forth.
This is a side carb engine with easy access to carb.

majortom-RCU

My Feedback: (40)

Your engine burns WD-40!? This is truly a product with a thousand uses!

Antique

My Feedback: (4)

deleted

Diablo-RCU

My Feedback: (1)

WD-40 is Stoddard solvent (made from dead dinosaurs) propelled by butane. You bet it burns.

platero

Here is my easy setup for walbro choke, it works fine and no holes in the cowl

Geistware

My Feedback: (16)

That is an awesome tip.
What is the material made out of and did you have to drill and tap that hole to retain the choke plate?

platero

the material is a square of aluminium almost the zize of the carburetor, drill with a drill bite, no gasquet was be necessary, the plastic is high impact, in first try it was aluminiun but not wrok well, this system has more than two years working ok...good luck

pe reivers

That picture is exactly the same as the ryoby choke.
Yes I know, but the question was. " what to do when the carb is not accessable?"

It just occurred to me that Diablo's solution is probably best:
solder (sodder for northerners? Us furreners find it hard through your dialects) a tube to the diaphragm vent hole, and connect a blow hose to it. For choking, rock the prop whilst "blowing the horn" Then tuck away that Gabriel thing into a no-harm location, and go ahead and start the engine. The lack of mechanical devices will keep that membrane better.

platero

generaly, to me carbs can use this method but some like 3W I use the stock system.

hilleyja

My Feedback: (3)

That is virtually identical to the choke assembly that comes on the Fuji BT-50SA.

After this picture was taken I changed my mind and mouted a Hitec HS-81 on the side of the engine mounting box and direct-connected the choke to the servo. My channel 6 VR switch controls the choke.

platero

ok ok but the engine in my photo is an Homelite 25 cc that i was purchased in wall mart for $20, because the rotor was broken

hilleyja

My Feedback: (3)

Nice fabrication.

As you can see, however, a walboro carburetor is not different in basic design here. Your same configuration could have been duplicated without the plate. All you need is a spacer and very thin, bendable (spring-like), washer and use one of the mounting bolts.