Walbro Carb Swap
 

G'day People.

I need help,I was looking for some 12mm carbs for my Ryobis and came across some WT324 models. Looked at this page on r/c universe http://www.rcuniverse.com/forum/m_23...tm.htm#2371019
Thinking that these are the carbs that I want bought 4 from the States and when they arrive there are to big for my needs and have a 16mm draught on the trottle side and 19mm on the choke side.

Well I stuck one on my Ryobi and got it to run but they are a too big as it drowns just a touch at the top end.

Well what I really want to know is the proper model number for a 12mm carb and if anybody is interested in swapping 12mm carb for a large one? As I find it hard to locate one here in Aus.

Thanks Adrian.

RE: Walbro Carb Swap
 

These carbs have an 11.11mm bore. There should be a number cast in the intake. In your case it should be 28 which is the intake size in 64ths of an inch. By the wat the carb appears to suoercede to WT-624 which is the same bore. Try this Walbro link to your carb. http://wem.walbro.com/walbro/product...24-1&Series=WT

RE: Walbro Carb Swap
 

Thanks Tim.

Had a closer look at these carbs and your are correct ,found 28 inside the inlet so it has to be the right carb. looks like I will have to go and do a bit more tuning just having trouble with high end mixture seems to be overfueling but will go and have another play see how it goes.

Thanks Mate.

RE: Walbro Carb Swap
 

It took me some tinkering as well. I'm using 11mm Walbros on 21, 23, 25, and 31 cc engines. I think you will find them a good choice once you get the adjusting finished.

RE: Walbro Carb Swap
 

Well went out this afternoon and played around with the carb settings and finally got the engine running good which makes me wonder how far can you push a ryobi before it goes pear shape.
I think 8000rpm is as far I would want go for a reliable engine anymore and I think you would be pushing it. I find the settings alot more delicate with the bigger carb and also the need for the choke for restarting after leaving for a short period of time.

Where with the standard carb I did away with the choke because it would start easy without it.
But there is definitely more power there. The standard carb gave me 7000rpm with 18x8 prop and the the new one is getting close to 8000rpm but I have no tach but it sure pumping out more power.

Adrian.

RE: Walbro Carb Swap
 

Unless my engines are started right back up after running I always use the choke. That is on motors up to a 61cc twin now. I am sure my DA-100 will be the same way. Also if you are getting 8000 RPM from your motor now I would not go any leaner. Remember that the prop is going to unload while in flight and be turning several hundred more RPM. I usually prop mine for less than 8000 RPM on the ground. I have made some of my test conversions run well over 9000 on the ground but boy were they wound tight and they sure did get warm. [X(]

RE: Walbro Carb Swap
 

Put a bigger prop on it and slow it back down to about 7300--7500RPM.

I can tell you from experience--they don't last long when you get over 8800RPM on the bench. I don't know how long it will last at 8000RPM, but after seeing one exploded--I don't think I'll push them past 7500RPM anymore.

Turning a bigger prop at lower RPM can provide just as much thrust or sometimes more than the prop you have now.

Put a bigger prop on it untill you get back down to 7500RPM. [sm=thumbs_up.gif]

RE: Walbro Carb Swap
 

Have read the hole post and checked the Walbro page w/database and nothing matched on my Walbro carb...
Type...Walbro WT 613
Venturi...24
When checked against the Walbro database, it shows the Venturi being 11.11mm but the number in the throught is 24 which is the size for 9.53mm...How come?
The carb is the original off the Evolution 26GT motor. Looking to replace it with a bit bigger carb venturi size (which one?) and one that has the choke spring/ball installed like the carb off the DA-50 motors.

RE: Walbro Carb Swap
 

Something strange happened with the WT-613 you have. Walbro's web page shows that carb and references it to a WT-512. Venturi on the 512 is 13.5mm and the WT-613 venturi is 11.11mm. The WT-512 seems way to big for a 26cc engine. A Zenoah 26cc currently uses a WT-643, 644, or 645 and they all have a 12.7mm venturi. The carb you have with that large of an intake bore must have been special to a particular engine. Walbro will make carbs that way for different OEM specifications. I am moving and have packed my Walbro bible. Maybe someone else here can look up what that carb was put on and for what OEM. The WT-644 and WT-645 on the Zenoah 26cc engines have chokes.

RE: Walbro Carb Swap
 

My wrong. I have the WT-481D carb that matches the Walbro data. Venturi stamped 24 with a 9.53mm opening.

RE: Walbro Carb Swap
 

hi! i have just swap a wt-305 carb into my homie orginal carb and i was wondering about the needle setting.
how do you set it? how are you going to increase or decrease, is it clockwise increase? or anti-clockwise?
thanks!

RE: Walbro Carb Swap
 

Screw them in (clockswise) gently till they bottom out and back em out a couple of turns. It shold start at that setting. Screwing them in will lean them and out (counterclockwise) will richen them. the needle closest to the engine is your low speed jet and the furtherest out is your high speed jet.

RE: Walbro Carb Swap
 

ernest2: Hey...we are here to help. Make sure you got good compression and good spark. Tell us what the engine is doing? like is it getting flooded with gas? Does it pop, or kick back. Are you cranking it over fast enough? Try setting the spark plug gap closer .020 I have wraped a short piece of cord behind the prop and started em that way. Be carefull not to catch rope in prop. Good Luck Capt,n

RE: Walbro Carb Swap
 

guys thanks for the tips, specially on setting the carb. i might more on it once i finish the airboat. the problem was on the fuel supply, i guess the filter is clog already. anyway i was able to fire it up once i switched the fuel supply.
ernest

RE: Walbro Carb Swap
 

ernest2: Try to find a fuel filter (felt) like used in a chain saw. Regards Capt,n

RE: Walbro Carb Swap
 

I filter the fuel with a filter in the fill line from the pump. Then no filter is needed on the plane and fewer joints to leak.

RE: Walbro Carb Swap
 

There is NO extra joints. You NEED a clunk in tank and that is where you need the felt filter. Do you see what I mean? Capt,n[:-]

RE: Walbro Carb Swap
 

One thing I do with the carbs is to pull out the fine mesh screen as they tend to get waxed up with some two stroke oils and just make sure that your mix is clean.

Adrian.

RE: Walbro Carb Swap
 

Anybody out there know how to figure out load factor for 3 bladed props. Tried the Prop forum but couldn't get an answer.

RE: Walbro Carb Swap
 

Seems to me I read somewhere that you reduce the diameter by 1" to arrive at an equivalent load to the same prop with two blades. I remember thinking that didn't seem like enough, but maybe so...

AV8TOR