Truckracer

My Feedback: (19)

Regarding the warning ..... a person can still replace diaphrams, gaskets and other simple rebuild parts. Only if you attempt to remove the throttle shaft and some related parts would you get into trouble. Also, there is a very non-standard one way valve pressed in the main body of these carbs .... don't mess with that unless you know what you're doing. Overall I don't care for the WT-813 very much as there are far better, well proven choices out there.

w8ye

My Feedback: (16)

Tell us about those choices?

Truckracer

My Feedback: (19)

The WT-645 as used on the Zenoah G-26 is a very well proven carb ... and if its used on a Zenoah it has to be good ..... right?? Also, as listed earlier, the current Walbro WT clone used on the DLE-30 really works well as is. If I had a bad one, I think I'd try another one to resolve the problem. I have no experience with the following but I understand the carb used on the early side carb 30s was slightly different. Someone would have to set me straight on that one though because my DLE-30 experience started with the rear carb version.

jedijody

My Feedback: (1)

The original DLE30 carb was changed, the biggest difference was in the external covers. They got rid of the metering cover that said Tillotson and had DLE cast into the pump cover. Minor metering changes inside but I can adjust both carbs and swap them from engine to engine and 90% of people would not know the difference. Both have a 7/16", 11.1 mm venturi. If one must have a Walbro there are many that will work well, all are WT series with 28-34/64" venturis, ones I've tried that work good are 739, 759, 645, and 805. In my experience, accelerator pumps on engines this size are usually detrimental.

captinjohn

I wish I had another DLE 30 to test a rotary barrel carb (in a warm envirement) & see what the out-come would be. I had one of these carbs on a 25cc Homelite engine that I owned. It was in a deep V boat. I found out how to tune these carbs for another guy that had the same set-up. I was real impressed on how it started and ran. The same good running at all speeds with every rotary barrel carbs I have used ,became evident. Even on equipment I rented....all engines with rotary barrel carbs ran more even through the entire RPM range. Next summer I will be doing that experiment. The carb I have now is modified only that the pump is ran via a pressure tap and a piece of fuel line to crankcase to catch the crankcase pulses....running pump. OK... time for the nay sayers.Capt,n

jedijody

My Feedback: (1)

What was wrong with the OEM internal pulse configuration?

w8ye

My Feedback: (16)

John has a Cyberwolf back crankcase half and reed block?

captinjohn

Nothing wrong with internal pulse configuration ...just on the carb I have, has no pulse hole to line up to the passage in the intake manifold. I will post a photo of it. This was not my mod...another guy did the tap...on several he sold. This is ok...this carb could be used with a 90 degree intake to keep the carb close in if you had a side intake engine. I do not have many extra carbs anymore...gotta use what I got! Capt,n

jedijody

My Feedback: (1)

John has the DLE back plate conversion, both it and the cyberplate were made with internal pulse accommodations for either position of the carburetor. If your carb doesn't have the internal pulse passages it has been changed and isn't an OEM DLE carb.

captinjohn

Yes that is what I use now.....it is myCARB that has no pulse hole at all...like none....so I just need to use it with the nipple that is there and make sure to hook a line to any where I can get a pulse from crankcase or side of intake manifold.
The other thing is too I got to finish my Holt engine while my eyes are good enough to do that. So my Holt engineis first place now. Let the snow fall...and it is too! Capt,n

flyaway01

Hi, I have a dle30 rear carb. If I fly inverted the motor dies, that is the low screw set at7/8 of a turn. If I turn the screw to1and 1/8 it runs very rich, sprays oil everywhere and inverted the motor stops burbling revs slightly higher and clears. I think I have a fuel starvation problem. The diaphragm with the needle is in the top position, so when turned to the bottom it dies. I have checked the clunk, there is free flow of fuel in all positions. I need some advice thanks.

w8ye

My Feedback: (16)

You may be turning your needle too much?

Turn it just a little bit, just enough to say you moved it, and see what the engine does?

rc34074

My Feedback: (5)

jedijody - you commented "In my experience, accelerator pumps on engines this size are usually detrimental."

How are they detrimental?

Ed

jedijody

My Feedback: (1)

An accelerator pump, is intended for applications where the engine needs to idle slow, consistent,and reliable for extended periodsthen punch the throttle tofull ornearly full throttle, the extra shot of gas carries the engine over until the airflow through the carb accelerates to the point it canpull enough fuel with it to sustain thehigh RPM. The problem with our engine application is they are very lightly loaded in the off idle and midrange RPM band and at least for most aerobatic and 3D flight the engines are run between off idle and about 3/4 throttle most of the time. If they had accelerator pumps they would be constantly pumping fuel into the engine and would flood it out. Also, accelerator pump carbs almost have to be designed for the specific size engine and use application, there is a very fine balance in correctly metering the fuel at off idle and midrange for small gas engines with accelerator pumps, that's why they are so rare. So, if the carb and accelerator pump isn'tcalibrated specificallyfor our engine size, type, and use, andwe only need the engine to idle for relatively short periods and most of the running is at athrottle valve positions that would constantly be pumping in extra fuel they won't work all that well.

There's a little more to it than that but those are biggest reasons as I view it. I've used accelerator pump carbs on small single cylinder 2-stroke engines in the past and in every case the metering of the pump volume had to made adjustable to suit the application,....you think people have a hard time adjusting a carburetor now with just two little needles, throw in an adjustable accelerator pump and for many the engine would become unusable.

Whistling Death

These kinds of threads are worth their weight in gold.

BadAzzMaxx

Just like when carbs were used on our automobile, Every time you pushed the gas peddle you squirted fuel into the intake.

Now with throttle body and fuel injected, A computer controls that for you.

Milton

w8ye

My Feedback: (16)

I can imagine in a 3D situation and jockeying the throttle while in a hover, that the mixture would get rich when using an accelerator pump

jedijody

My Feedback: (1)

Exactly, unless of course one wanted to pay the bill for engineering the carburetor for the specific size and use of the engine, then add the increased manufacturing cost for the small batch size that won't suit any other application. No one would pay $150-$200 (hypothetically) for a carburetor for their $300 engine just to eliminate a little bit of midrange burble.

captinjohn

More Data on Walbro Carbs<hr /><table border="0" cellpadding="4" width="100%" height="186"> <tbody> <tr> <td height="1" valign="top"> <h4 align="left">Typical Walbro Problems</h4> <p align="left">They're really quite reliable, but when problems arise, they are frequently one of these.</p> <ul>[*] <p align="left">The small filter on the fuel-intake side clogs. Clean it out by removing and spraying carb cleaner through in the opposite direction of normal fuel flow. Re-insert using a pencil eraser.</p>[*] <p align="left">The float diaphragm degrades and reap havoc on tuning, especially the low end and idle.</p>[*] <p align="left">The internal needle valve WILL leak when they get old or worn out. If you notice gas dripping from your carb, or if the idle gets unreliable, replace the needle valve and adjust the lever even with (or slightly below) the carb housing if you don't have a gauge.</p>[*] <p align="left">The fuel pump membrane gets stretched and/or sometimes hardens from the gas. It needs to be replaced occasionally. If your pump doesn't pump properly, (1) it will be hard to start (2) it will tend to run lean, and opening the needles won't help much if any.</p>[*] <p align="left">Erratic idle, or no idle is often traced to a bad internal needle valve, bad float diaphragm, bad pump, and most common... crap in the carb. You may also have an air leak!</p>[*] <p align="left">The pop-off pressure is out of the normal range. About 12 PSI is normal. Pop off pressure is how much pressure is required to pop the main-jet needle off of its seat. The fuel pump pushes fuel against a spring. Either having the wrong spring, a cut spring or stretched spring can affect this pressure.</p>[/list]<p align="left">All Walbro carbs will run in any position, but they tune "best" as a side draft carb meaning the airflow intake is horizontal. The down draft position tends to run a little rich at idle, and the updraft tends to run a little lean at idle although it's easily tuned regardless.</p> </td> <td height="1" valign="top" width="207"> <p class="caption"></p> <p class="caption">This carb is equipped with a high speed check valve and external fuel pump pulse inlet. Diagrams courtesy tech.flygsw.org</p> </td> </tr> </tbody></table><table border="0" cellpadding="4" width="100%" height="186"> <tbody> <tr> <td height="1" valign="top"> <h4 align="left">Fuel Pulse</h4> <p align="left">Your ENGINE will determine which pulse inlet type you need. If the engine carb mounting surface has a hole drilled into the crankcase you will use the STANDARD pulse port and the optional (if you have it) port <u>must be closed off</u>. If there's no hole drilled, you will find a fitting located somewhere on your crankcase. Use a piece of fuel line to connect the crankcase fitting to the fitting on the optional pulse inlet. There's no need to block off the standard port, as it's already blocked off by the engine mounting.</p> <p align="left"><u>The carb must get a pulse signal from the engine!</u> This signal "pushes and pulls" on the pump diaphragm which feeds the carb fuel.</p> <h4 align="left">Float, Needle &amp; Seat Setting</h4> <p align="left">This critical setting is the primary way to adjust mixture on some Walbro carbs such as the WG8 used on Top 80 motors. Apparently Walbro offers a setting gauge to properly set the height of the lever for each model. Without that gauge you'll have to use trial &amp; error which is a pain since you must open up the carb for each adjustment. In general, the lever will be parallel to the carb base. If the lever is too high, the mixture will be rich, too low and it will idle ok but be lean at midrange and above. It may also run the float cavity dry at full throttle and die, regardless of your highspeed / lowspeed needle settings.</p> <p align="left">The needle valve seat is pressed into the carb base. Don't remove it without having the correct tools and setting gauges.</p> </td> <td height="1" valign="top" width="207"> <p class="caption" style="margin-bottom: 6px"></p> </td> </tr> <tr> <td height="1" valign="top" colspan="2"> <div align="center"> <h4 align="left">Troubleshooting</h4> <center> <table border="1" cellspacing="1" width="100%" style="border-collapse: collapse"> <tbody> <tr> <td width="259">Problem</td> <td width="480">Possible Fix</td> </tr> <tr> <td width="259">The engine stalls when accelerated</td> <td width="480">Highend needle way too lean, or lowend needle slightly lean</td> </tr> <tr> <td width="259">Four strokes as fast idle, mid RPM</td> <td width="480">Lowend needle too rich, float diaphragm needle lever slightly too high</td> </tr> <tr> <td width="259">Engine goes lean in flight</td> <td width="480">Highend needle slightly lean <u>AND lowend needle is rich</u>, float needle lever may be set too low</td> </tr> <tr> <td width="259">Engine goes rich in flight</td> <td width="480">this is a special problem with cowled in engines. the float diaphragm cover vent will need work (SEE NOTE 1)</td> </tr> <tr> <td width="259">Engine runs good, but no idle at all</td> <td width="480">There's crap in the idle jets, the carb will have to be removed and cleaned. You may also have an air leak at the base of the carb. The throttle butterfly could be damaged or worn out.</td> </tr> <tr> <td width="259">carb leaks fuel when not running</td> <td width="480">float needle is bad or has crap stuck in it, or the float lever setting may be too high, or the float diaphragm is bad.</td> </tr> <tr> <td width="259">My engine four cycles momentarily when I back off the throttle, then runs normal</td> <td width="480">This is perfectly normal for carbs NOT equipped with a "check valve" highspeed jet. If you do have the check valve, then your float needle setting is slightly too high, or your float needle is leaking a little.(SEE NOTE 2)</td> </tr> <tr> <td width="259">the fuel leaks back into the gas tank when it isn't</td> </tr> </tbody> </table> </center></div> </td> </tr> </tbody></table>

captinjohn

More Carb data on accelerator pumps<hr /><div>The Carburetor.... Very Trick Indeed!</div><div>At first glance it resembles a WT-257...but it contains the purge primer set up like a stock carburetor has. Looking closer though reveals it to be NOTHING like a WT-257.

I am going to get into this deeper than likely required, but due to the UNIQUE nature of the Carburetor's configuration I feel it's worth noting.

* Walbro has equipped this carburetor with an Accelerator Pump Circuit that gets actuated by throttle shaft rotation. Photos will show "some" of the parts that make this circuit tick.
* Next is the HIGH speed delivery discharge. NO longer do we find just a hole on the edge of the venturi, but instead we find a brass delivery jet pressed into the body projecting into the carburetor bore slightly behind the apex of the venturi.... interesting.</div><div align="center"> </div><div>OK, I have to confess, this configuration while NEW &amp; GROUND BREAKING for a hobby engine, is actually a design that has been around for 25+ years, and just applied to this specific carburetor.</div><div>** Note: The actual size of the throttle bore and venturi bore are the same as the 257,488,771 and stock carb. ( .625 on butterfly and .500 at venturi.</div><div>The CFM rating while not measured, should be very close to the others.</div><div>So here it is, the "What &amp; Why" of how these changes make a better carburetor for us model boaters.....

The Accelerator Pump Circuit</div><div>Having it allows the WALBRO engineers to calibrate the carburetor to have very crisp and accurate fuel delivery attributes. The low speed circuit can be set up so the engine will run very clean at slower engine speeds without loading up,and have a high speed circuit that is better isolated from the low circuit giving it finer mixture control at the needle. The accelerator circuit, because it is operated by throttle shaft rotation,gives the engine a SHOT of fuel if opened quickly, or has little effect if opened slowly. (Pump still works, but no shot is given, just a bleed out of fuel as throttle is slowly applied).
This allows an engine to run REALLY CRISP, yet NOT stumble when the throttle is suddenly opened. That&rsquo;s a GREAT thing!

Next is that odd High Speed Delivery Jet....</div><div>First off the brass jet actually contains a "Disk" style check valve right at the outlet. This design allows vacuum from the venturi to lift the disk and let metered fuel flow out into the air stream, BUT ... when air flow changes direction within carburetor bore, the disk is blown down over the discharge hole shutting off the fuel flow from jet.
* What this does is help eliminate excessive fuel fogging / spit back out of the carburetor. Also because fuel is discharged out away from the edge of the venturi, it aids in having better fuel atomization.
Note: All piston ported 2 strokes exhibit fuel spit back to some extent. The greater the intake duration the worse this gets.</div>

Antique

My Feedback: (4)

No big deal taking the shaft out, someone put the carb together in the first place, just be careful to not lose any of the parts....Put the parts in the hole, push the ball down into the spring while putting the shaft in...

captinjohn

Antique/ or anyone....how do I find a Hi-speed needle for my RedMax EB 431 blower engine? I looked on the Walbro parts finder and it said ...No longer avilable. It is a HDA carb....will any others fit? Thanks Capt,n

allans

My Feedback: (11)

I have 2 DLE 30's . One runs great . The other has all the symptoms of the carb probs discussed above.
Is it better to replace the carb with a DLE carb or a Walbro?

An if the Walbro which one?

Thank you

azalner

My Feedback: (8)

There is nothing wrong with the DLE carb, and for $35.00 how can you go wrong?

AJZ

Gabrielsande

Hi guys

Spent few minutes trying to explain my problem and I dont know what button I hit ,went out of my browser!!

so here we go again, I have a dle 30 rear carb with the original walbro like carb, never gave me a trouble since 2009 despite the normal rough rich idle, last week replaced all the gasket and diaphragm and it started to surge at 1/4 stick, so landed and adjusted the low end a bit reacher,and it got better, but still doing it a bit in different stick positions, so while I sort the carb out probably adjusting the fuel flow leaver, Im tempted to try a new walbro I found in my spares box, cant remember wy I bought it! anyway the problem is the carb is a WT-934 and I cant find much info about it to see if will suit the engine, the bore is bigger has a 32 stamped in the intake and has no choke which doesn't bother me,because I never use the one in the original carb, the engine after priming it a couple of turns fires up with an align starter at the first attempt.

So anybody know about this WT-934 engine application cons and pros?

thanks!