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carburator cleaningI

Old 11-25-2014, 01:25 PM
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dirtybird
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Default carburator cleaningI

I dumped my NGH 26 in the dirt. Even though I had a metal screen over the intake tro keep the big stuff out a lot of dirt went into the carb.I removed the carb and dissembled it. The little screen was full of dirt. I removed the screen and flushed out the hole under it. I actually removed the little plunger under it and flushed the hole. I had a hard time putting thet little spring back but I finally made it. I removed the needles and checked for ant debris under them
After reassemble the engine wii still not start. If I put the choke full on I can get a short burst. Then if I open the choke I can get another short burst. Its obviously starved for fuel. What do I need to do to clean it out?
Old 11-25-2014, 02:14 PM
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speedracerntrixie
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Dirty, you may still have some debris in there but then again you may not. By plunger I am going to assume it was what is commonly referred to as the metering needle. Its rubber tipped and has a triangular cross section. It's adjustment is critical to the carb performing correctly. If the activation lever for the needle has been bent even very little it could be your issue. The first thing I would do if I was you is remove the diaphragm cover and diaphragm and take a look at the lever. By using a razor blade as a straight edge against the carb body the lever on the opposite side of the fulcrum should be parallel to the carb body. If its farther down it will cause the metering needle to not allow fuel past, if it's up too far it will prevent the needle from sealing and you will get gas dripping from the carb. Too much spring tension will cause what you are experiencing too so check that the spring is fully seated in it's hole.
Old 11-25-2014, 04:10 PM
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dirtybird
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The metering needle lever must e the problem. I bent it down until it is level with the carb body and now I get no gas thru. The motor wont even pop with the choke full on.Before I donked it I would choke it until gas dripped out.(inverted motor) Then it would start right up I can't get it to drip gas at all now.
The diaphram was good before, I don't see why it would be a problem now>
Any other ideas?
Old 11-25-2014, 04:52 PM
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My way of thinking is if the engine ran good before the bump, the needle lever should not have been changed. Look for a bad diaphram or miss assembled parts. Take carb apart & take H & L needles out and make sure all passages ways are clear. Hold the diaphram up to a bright light to see if it got damaged from removal. Also check pulse passage way from & to carb. Capt,n
Old 11-25-2014, 05:49 PM
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dirtybird
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Unfortunately I I bent that lever arm when I put that spring back in.But with it way up too high I could not get fuel to drip from the carb.That makes me think tjhere is some other passage way clogged.If I take the needles out where do I blow or flush to clear the passageways?
I am out of time tonight. I will have to get back to it tomorrow.
Old 11-25-2014, 06:18 PM
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speedracerntrixie
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Dirty, it's quite difficult to describe the lever adjustment. There are several good YouTube videos showing rebuilding of Walbro carbs. I think watching a few of those videos would really help. On a side note, dirt in your internal filter screen was not a result of your accident. This is debris that is coming in from your fuel system. Those links loaded funny. Click on the times to get to the videos.



► 18:27► 18:27


www.youtube.com/watch?v=K5C86ZYNcnI





► 6:35► 6:35
www.youtube.com/watch?v=RfzzTilqwo0



Old 11-26-2014, 07:56 AM
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dirtybird
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OK I went to utube and watched the rebuild and cleaning videos. I should have done that first. I found how to put that lever and spring back in without destroying it. I am going to get some carb cleaner and remove the needles and spray through all the holes. I have several old carbs that I got off ebay for practically nothing. I will take the lever out of one of those and try again with it installed.
In reading the Walbro manual I was surprised to learn that the screen has more purpose than catching debris.I will have to replace it.
The dirt got into the screen ared quitsa because I unfortunately installed the external fuel filter backwards after it fell off. It dumped all the debris it had caught back into the fue
update:
I thoroughly cleaned the carb and still no joy.
Its the same as yesterday choke it and it runs a short burst an quits.
I give up. I have other toys to play with

Last edited by dirtybird; 11-26-2014 at 01:34 PM.
Old 11-26-2014, 03:28 PM
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speedracerntrixie
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What did you adjust the needles to? Set to 1 turn on the low and 2 turns on the high. These will no doubt be rich settings but should get you running. With the metering lever set as per the video, all passages blown out with spray carb cleaner and needles set to above settings I have yet to see an engine that would not at least run. Another thing to check is that the throttle butterfly is in correctly. With some carbs it can be installed 180 degrees out. There may be a notch that lines up with passages in the carb Venturi.
Old 11-26-2014, 04:42 PM
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I didn't take time yet to watch the longer video, but there are a few things to mention about the shorter one. He doesn't mention taking out the adjusting screws, nor cleaning the carb at all. I like to use WD-40 to blow through each and every passage in the carb, verifying that each passage flows. I used to use carb cleaner for this, but if you are working on a Zama carb, the carb cleaner can instantly destroy some of the check valves in the carb. So I just switched to using WD-40 and/or compressed air to clean out and check flow on the various passages.

He also doesn't mention checking the needle lever height, which one should do. And lastly, he put the regulator cover back on improperly. When he took the carb apart, the hole in the regulator cover was pointing towards the mixture adjustment screws. He put it back with the hole off to one side. In a machine such as a leaf blower, weedeater, chainsaw, etc., this could put the hole facing into the cooling airflow, causing the carburetor to go rich, especially at higher rpms. Same thing with a model airplane. If you point that hole forwards, the prop blast and/or flying airflow can pressurize the carb regulator through that hole and cause you tuning problems.

AV8TOR
Old 11-26-2014, 05:25 PM
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av8tor, I agree completely with you regarding the use of carb cleaner on our small carbs. I hear it recommended all the time but in personal use, I have seen it destroy rubber parts so I avoid it completely. Most of our smaller carbs use a simple capillary screen arrangement for a HS check valve but many of the larger carbs use a rubber valve held in place with a spring, all assembled in a brass housing. If the rubber valve gets damaged the carb will no longer function w/o replacing the valve. Some of our smaller WT carbs also have this rubber checkvalve so caution should be exercised. Carbs with accelerator pumps also use check valves but few of our carbs use these pumps. A carb with a plugged or damaged HS check valve may idle nicely but not transition to full throttle. If it is just damaged, the engine may run at full throttle but require the HS needle be farther out than normal.

These days in place of carb cleaner, I use electronic parts cleaner in a spray can which does not damage rubber or plastic but still has excellent solvent properties.
Old 11-26-2014, 06:34 PM
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dirtybird
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Originally Posted by speedracerntrixie
What did you adjust the needles to? Set to 1 turn on the low and 2 turns on the high. These will no doubt be rich settings but should get you running. With the metering lever set as per the video, all passages blown out with spray carb cleaner and needles set to above settings I have yet to see an engine that would not at least run. Another thing to check is that the throttle butterfly is in correctly. With some carbs it can be installed 180 degrees out. There may be a notch that lines up with passages in the carb Venturi.
Where it ran before L,S. 1-1/2 turns out H.S. 3/4 turns out.
Old 11-26-2014, 06:40 PM
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Guys, thanks for the heads up on the carb cleaner, I haven't had any issues using it but I will switch to WD anyways. No need to take the chance. Dirty, those needle settings seem to be backwards to me. I have yet to run a gasser where the low needle was open more then the high. Not saying it's impossible, just I haven't seen it.
Old 11-26-2014, 06:41 PM
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Sometimes the needles are not the same. Any chance the HS and LS needles got interchanged?
Old 11-26-2014, 06:44 PM
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speed, brakewash is another good alternative that won't damage rubber.
Old 11-26-2014, 10:45 PM
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Re: those check valves, you also have to be judicious where you blow compressed air. It too can damage those check valves by unseating and/or blowing the rubber out.

To the OP. This will sound crazy, but if you have an extra ignition unit around, try it. Also discharge test your battery, and run the ignition straight to the battery eliminating any electronics or switches you might have. I once had an engine that acts exactly as you describe, and it turned out to be the ignition. When I tried a 6 volt battery instead of my 4.8, the engine started and ran normally. I got the tip from Bill at CH Ignitions. At any rate, it wouldn't take much to try it and eliminate it as a possible culprit.

AV8TOR
Old 11-27-2014, 08:23 AM
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dirtybird
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It could very well be the ignition. I pulled the spark plug and found a nice spark,but then when i put some gas in thru the plug hole,and reinstalled the plug, I couldn't get a pop out of it. It should have ran that charge out.
I am thinking it might be that plug cap has an intermittent connection. Its been pounded in the ground hard. I once broke the plug under it. A nice new $16 plug.
Unfortunately, I don't have a new ignition to try and don't feel like buying a new one.
I am running A123 batteries with two diodes in series to get the voltage down to 4.9. I even tried a different A123
Old 11-27-2014, 12:09 PM
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What can easily happen in a crash, or even a "nose over" landing, is the metal plug cap takes a hit. That forces it to move rearwards momentarily and the connector end of the plug pokes a hole through the silicone insulation inside the plug cap. It can be invisible to see, but can cause the ignition to not work because the spark jumps through the insulation to ground instead of through the plug to make a spark for the engine to run. Check the "stickies" in the beginning of the forums for a post made by Jodi showing all the steps for checking the ignition. It's an excellent and informative post. Keep in mind though, that it is entirely possible for an ignition to show a visible spark when testing, but still not make the engine run properly. Been there, done that......

AV8TOR
Old 11-27-2014, 12:22 PM
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Ok, here is a stupid question for you. Did you put the gasket back into the carb between the carb and the engine? I did the same exact thing. It was upside down so fuel wasnt reaching the port for the carb. try that if you have something like this.
Old 11-27-2014, 01:45 PM
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You mentioned in one of the posts that you can't get gas dripping out?
Depending on how hard you hit, did you check the pickup in the tank
I had the same thing on a Quadra and the pickup tube was kinked up to the front and wouldn't let gas out
Old 11-27-2014, 09:26 PM
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dirtybird
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The tank is ok and not leaking. The carb spacer and gasket are in correctly.The engine has an external pulse line. I put in a new.piece of fuel tube on it. I found it had fell off. I dont know how long that has been screwing me up. try again tomorrow.
I just might spend $10 on a new plug cap if it still wont run.
Old 11-28-2014, 06:27 AM
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My way of thinking is if the engine ran good before the bump, the needle lever should not have been changed.
Old 11-28-2014, 09:05 AM
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dirtybird
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Originally Posted by gqlhonourbv
My way of thinking is if the engine ran good before the bump, the needle lever should not have been changed.
You are right but check post #5
Old 11-28-2014, 01:08 PM
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Ok, now I have taken time to watch the longer video, and it is better but I have some comments about it too. For most common rebuilds the way he shows doing it would be fine. But there are a few things I do differently.

For one, when spraying the carb with cleaner, or as I do, with WD-40, when spraying in the regulator chamber I spray through the holes that lead to the high and low speed circuits. When I do this, I want to see the spray coming out of both the high and the low speed needle holes respectively. You rarely find a blockage on the high speed circuit, but sometimes you do on the low speed. If so, you need to blow compressed air through the needle hole and try to get it cleaned out. Sometimes you may need to soak it for a while, then blow it out again.

Then, I like to hold my fingers over those same holes in the regulator fuel chamber to close them, and spray though the needle holes themselves. While doing this, hold the throttle open and look in the venturi, or carb throat. When doing the idle needle hole, you should see the spray coming out the 2 or 3 idle and midrange holes in the venturi, and when you spray through the high speed needle adjustment hole, you should see spray coming out of the high speed orifice. Sometimes that orifice is a brass valve sticking into the venturi, sometimes just an orifice hole, but you should see spray coming out of it in any case. If not, find out why.

Lastly, I always give my gaskets a shot of WD-40 while I am fooling around with the carb to soften them up a bit and get a better seal. Sometimes dry gaskets compress more after they have been exposed to the fuel/oil, and then your regulator and fuel pump covers might be loose. I also do not assemble the carb dry the way he shows. I either put a good shot of WD-40 in both the fuel pump and regulator chamber, or pour some fuel/oil in there. This helps the carb seal well and pump right away when put into use.

Ok, I'm off my "carb soapbox" now.... Just little tricks I have learned to use over the years. They only take a moment, and might save you from putting the carb back on the engine, only to still have problems with it.

Last edited by av8tor1977; 11-28-2014 at 01:16 PM.
Old 11-29-2014, 03:24 PM
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I I am fairly sure I know what the problem is. I bent the little leverl arm trying to install it and the spring. So now when I set the lever arm parallel with the carb base the needle is out of place. The lever arm must be in the correct position to get the correct stroke from the diaphragm. But at the same time the forks must be in the correct position to lift the needle during the diaphragm stroke. This is not mentioned in the ytube videos. apparently they assume the lever is in correct alignment. But I bent mine.
I have ordered a repair kit that has the alignment tool included..
Old 11-29-2014, 03:31 PM
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Yes, that needle lever adjustment is important and pretty sensitive. Another way to assemble it is to put a toothpick through the hole in the lever to help you capture and guide the little spring into position.

AV8TOR

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