My 4016 with 16HP Vanguard engine has been surging more and more recently mostly at idle but I can hear it a little at full throttle. I pulled the air filter assembly off, removed the carb top and did a basic cleaning. I found the jet had some crud in the end which I was able to blow out. I took a bunch of pictures for a how-to but then I discovered a better video on youtube. I used a can of CRC carb cleaner and I recommend safety glasses and a rag over the carb when spraying into passages (cleaner can spray back in your face).
Vanguard 12.5HP, 14HP & 16HP all use the same bottom end with a different carb. The 18HP and 20HP (no longer marketed) have a bit more displacement but appear to have a similar carb setup. The 23HP and possibly the 21HP use a two barrel carb and have even more displacement.
Fully removing the carb on the on 12.5HP, 14HP & 16HP (possibly 18HP?) require disconnecting the stub shaft from the flywheel, unbolting the engine from the frame and sliding it forward to remove the various shrouds. I'm not sure whats required on 21HP & 23HP vanguards.
I'm still having trouble with the engine surging. After mowing the lawn, the surging was back especially at idle. I made a second attempt at cleaning the carb. More junk in the pilot jet. Also cleaned out the bowl. Ran good at first while towing the fertilizer spreader around but the surging came back again.
I'm going to clean the carb a third time. I may pick up another kind of carb cleaner and I plan to blow the pilot get out with compressed air this time.
My gas isn't that old. Since the initial carb cleaning, I've refilled my 5 gallon gas can and burned through about 3 gallons. I've also been running seafoam with the new gas (about 1oz to a gallon).
MattA wrote: ↑Thu Sep 21, 2023 9:13 pm
I'm still having trouble with the engine surging. After mowing the lawn, the surging was back especially at idle. I made a second attempt at cleaning the carb. More junk in the pilot jet. Also cleaned out the bowl. Ran good at first while towing the fertilizer spreader around but the surging came back again.
I'm going to clean the carb a third time. I may pick up another kind of carb cleaner and I plan to blow the pilot get out with compressed air this time.
My gas isn't that old. Since the initial carb cleaning, I've refilled my 5 gallon gas can and burned through about 3 gallons. I've also been running seafoam with the new gas (about 1oz to a gallon).
Can you describ the junk you are getting out of the carb? In therory with a good filter nothing should get into the carb but gas . That being said , we all know how ethanhol(water absorber) and additives in the fuel break down and create a vasilene looking sludge before creating corrotion . Is the the junk black ? If so I would say you need to change fuel lines and or fuel pump as they are breaking down inside . I have had issue with a few filter recently not actually sealed inside let debrie past . The carb is obviously the source of the surging , but where is the junk coming from is the million $ question.
Once you get it sorted out , drop your mix of seafoam to 2 oz per 5 gallon for maintaining fuel.
MattA wrote: ↑Thu Sep 21, 2023 9:13 pm
I'm still having trouble with the engine surging. After mowing the lawn, the surging was back especially at idle. I made a second attempt at cleaning the carb. More junk in the pilot jet. Also cleaned out the bowl. Ran good at first while towing the fertilizer spreader around but the surging came back again.
I'm going to clean the carb a third time. I may pick up another kind of carb cleaner and I plan to blow the pilot get out with compressed air this time.
My gas isn't that old. Since the initial carb cleaning, I've refilled my 5 gallon gas can and burned through about 3 gallons. I've also been running seafoam with the new gas (about 1oz to a gallon).
Can you describ the junk you are getting out of the carb? In therory with a good filter nothing should get into the carb but gas . That being said , we all know how ethanhol(water absorber) and additives in the fuel break down and create a vasilene looking sludge before creating corrotion . Is the the junk black ? If so I would say you need to change fuel lines and or fuel pump as they are breaking down inside . I have had issue with a few filter recently not actually sealed inside let debrie past . The carb is obviously the source of the surging , but where is the junk coming from is the million $ question.
Once you get it sorted out , drop your mix of seafoam to 2 oz per 5 gallon for maintaining fuel.
Inside the carb looks decently clean. I did remove the gas and remove what little brownish red sediment I found. I'm thinking I'm not getting the pilot jet fully cleaned out. The hole in the end of the pilot jet is partially clogged when I clean it and when I'm done I can see though it. I'm thinking of using some compressed air to help clean it out. Maybe soak it in some cleaner. I do have a new OEM fuel filter to put on it. Fuel pump was new last year or the year before. Changing the fuel pump didn't change anything in the past so I kept the old one. The fuel line between the carb and fuel pump and between the fuel pump and valve cover were replaced ~6 years ago. Not sure if I replaced the fuel filter to fuel pump section but I have more fuel hose. The tank to fuel filter hose has not been replaced.
Adding a picture from my phone. This was before I cleaned the carb, first attempt. Little bit of crap in the bottom left by the fuel shutoff solenoid.
From the pictures on my phone it looks like I cleaned the carb in 2019 and 2016. I think it was 2019 that I pulled the engine to remove the carb for cleaning. Engine ran good afterwards.
This was in 2016 after I bought the tractor. It was a snowblower tractor only and had been sitting. The owner had passed away.
You could get junk from the tank or along the fuel line, which disintegrates with time. Long term fix is to replace the fuel line and clean/coat the tank (if metal). Short term fix is a filter.
Eugen wrote: ↑Fri Sep 22, 2023 10:17 am
You could get junk from the tank or along the fuel line, which disintegrates with time. Long term fix is to replace the fuel line and clean/coat the tank (if metal). Short term fix is a filter.
Another thing to consider is maybe an air leak?
The modern fuel tanks are plastic. Fuel filter is up front between the steering tower and the engine.
Most forum topics and videos point to the carb. I ran into one that said repeated carb cleanings didn't help, the problem was the governor adjustment. The service manual says to fix the carb before adjusting the governor. I did check the governor arm adjustment but not the stops yet. Thanks for the air leak idea.
Well I got about an hour of free time tonight. Pilot jet was again plugged. I stuck a piece of stripped 26AWG? solid core wire though the pilot jet several times and nothing came out. Didn't seem to clear the end hole out either. Compressed air shot backwards through the jet cleared the end hole out. I also shot some crc carb cleaner through the pilot jet a few times letting the jet sit between cleaning attempts. I also shot compressed air down the pilot jet hole. The last thing I did was drain the fuel tank through the existing filter and install a new filter. The old filter had plenty of flow. Maybe a quart or so per minute. It's raining and the kids are asleep. I'll run it in a few days when I mow the lawn.
MattA wrote: ↑Sun Sep 24, 2023 8:52 pm
Well I got about an hour of free time tonight. Pilot jet was again plugged. I stuck a piece of stripped 26AWG? solid core wire though the pilot jet several times and nothing came out. Didn't seem to clear the end hole out either. Compressed air shot backwards through the jet cleared the end hole out. I also shot some crc carb cleaner through the pilot jet a few times letting the jet sit between cleaning attempts. I also shot compressed air down the pilot jet hole. The last thing I did was drain the fuel tank through the existing filter and install a new filter. The old filter had plenty of flow. Maybe a quart or so per minute. It's raining and the kids are asleep. I'll run it in a few days when I mow the lawn.
Well, I'm confused though, by the source of material which plugs the jet . What do you think?
MattA wrote: ↑Sun Sep 24, 2023 8:52 pm
Well I got about an hour of free time tonight. Pilot jet was again plugged. I stuck a piece of stripped 26AWG? solid core wire though the pilot jet several times and nothing came out. Didn't seem to clear the end hole out either. Compressed air shot backwards through the jet cleared the end hole out. I also shot some crc carb cleaner through the pilot jet a few times letting the jet sit between cleaning attempts. I also shot compressed air down the pilot jet hole. The last thing I did was drain the fuel tank through the existing filter and install a new filter. The old filter had plenty of flow. Maybe a quart or so per minute. It's raining and the kids are asleep. I'll run it in a few days when I mow the lawn.
Well, I'm confused though, by the source of material which plugs the jet . What do you think?
I was thinking the same thing. It’s a plus for sure that your able to see the problem and clean the main jet but there seems to be an inordinate amount of junk getting into the carburetor. I was thinking it might be worth pumping some gas into a clean container to see what’s in it. I realize this has a plastic gas tank but there still could be junk in it.
The filter had good flow but it’s possible it’s letting junk through as well.
Just some things that came to mind as I was reading. I’m interested to see what you find.
MattA wrote: ↑Sun Sep 24, 2023 8:52 pm
Well I got about an hour of free time tonight. Pilot jet was again plugged. I stuck a piece of stripped 26AWG? solid core wire though the pilot jet several times and nothing came out. Didn't seem to clear the end hole out either. Compressed air shot backwards through the jet cleared the end hole out. I also shot some crc carb cleaner through the pilot jet a few times letting the jet sit between cleaning attempts. I also shot compressed air down the pilot jet hole. The last thing I did was drain the fuel tank through the existing filter and install a new filter. The old filter had plenty of flow. Maybe a quart or so per minute. It's raining and the kids are asleep. I'll run it in a few days when I mow the lawn.
Well, I'm confused though, by the source of material which plugs the jet . What do you think?
I was thinking the same thing. It’s a plus for sure that your able to see the problem and clean the main jet but there seems to be an inordinate amount of junk getting into the carburetor. I was thinking it might be worth pumping some gas into a clean container to see what’s in it. I realize this has a plastic gas tank but there still could be junk in it.
The filter had good flow but it’s possible it’s letting junk through as well.
Just some things that came to mind as I was reading. I’m interested to see what you find.
I've got a new OEM briggs filter on it now. I'm thinking it may be possible that I'm simply not getting the junk out of the pilot jet. The carb still looks good and clean inside. I'll keep you guys posted.
I chopped up to about 8" of thick heavy grass off my lawn tonight. It's been raining a lot here in recent weeks. Anyways the engine ran much better. Seems to have a bit more power now which I really put to use tonight. The engine still seems to hunt a bit at any rpm but it's much better than before. I'm going to perform the carburetor idle fuel adjustment, correct the governed idle rpm (1200rpm to 1750rpm) and set the governor stops per the service manual. Hoping to do this tomorrow and then mow my lawn again to remove the thick layer of grass clippings.
The Briggs can be very finicky. As far as the governor adjustment you may end up regretting at they too are very temperamental with this as well and you can create more aggravation for yourself. There is a special tool for adjusting the tabs and if tackling this I highly recommend getting it. Now again with the temperamental Briggs, you really need to pull the the carb off to clean right, pull all the jets, the bottom one you can only get by pulling fuel solenoid. and really should pull welsh plug, clean passages and put new plug in. Be careful with compressed air as you can blow welch plug out so dont use lots of psi. If you have access to ultra sonic cleaners they are great. We do a lot of carbs,many also sent to use for rebuilds or cleans. We use a heavy chem dip and soak, and 2 cycles through a good quality ultra sonic at temps of 175 degrees, then do the manual and air cleaning before assembly. Some times you can get away with pulling the top of the carb and spraying what passages and removing what you can. But if it keeps happening you should pull the carb. The Briggs are very fast and easy to pull the engine. We have a video on how to pull the Brigs for Head Gaskets, coils, carbs etc. Good luck.
Well you guys already know what happened
Before mowing this past weekend, I set the governed idle to about 1500rpms. I also did some reading on the old forum and Bob macgregor aka mad Mackie had recommended increasing the carburetor idle stop from 1200rpm to 1400rpm or 1450rpm. I did about 1400rpm. When I started mowing, the rpms climbed to about 3800rpms. I adjusted the governor high rpm tang to bring the rpms back to 3600 or so. I haven't made adjustments to the high rpm tang since 2019 when I increased the rpms from 3300 to 3600. Anyways power seems to be down a little. The tractor struggles to climb the small hill in my front yard more than usual. When I finished mowing, the surging was back. I'll pull the engine, clean under the tins and clean the carb at the end of the mowing season. I haven't done that since 2019.
So back to this stupid problem. Last fall I pulled the engine apart, cleaned the debris from the engines cooling fins, took the carb apart and tried to do a good cleaning. I actually attempted cleaning it several times to make sure it was good and clean. I put it all back together and the tractor started much easier and seemed to run better. Mowing season was over at that point but I did get two lousy snow storms over the winter to use it. Ran ok but seemed down on power. Over the winter at @DavidBarkey suggestion, I checked the valve lash and the plug gap. Valve lash was 0.005" and the range is 0.004" to 0.006". Spark plug gaps were 0.0295" and 0.030". Recommend gap is 0.030". Plugs are Briggs and Stratton 694385 long life plugs. Plugs have about 250hrs on them and are about 6 years old. I believe the air and fuel filters were new last year and I just changed the oil + oil filter.
Today I attempted to cut my grass and the tractors so down on power that its basically useless. Runs 3600-3700RPM with no problem but driving up the small hill in my front yard with the deck running causes the rpms to drop rapidly. Same for thicker grass. I can literally be doing like 0.5mph or less up the hill and rpms are below 3000. I pulled one plug wire, started right up and idled. Swapped pulled plug wires and again it started right up and idled. I even tried engaging the deck with either plug wire pulled. The engine struggled in both cases. Gas cap vent is clear.
Most of the gas in my tractor was from last fall. I only used about a gallon over the winter blowing snow. I put stabilizer in it last fall. About half a gallon of the gas was 109 octane ethanol free race gas (how I got this is a bit of a $70 sore spot). I added about a gallon of fresh gas before mowing today. This gas was purchased within the past month. An our into mowing, I added another gallon of fresh gas and when finishing I added another gallon of fresh gas. Hard to tell but I think I burned around the usual 2 gallons of gas while mowing. I don't think the gas is the problem, most of the gas in the tank is new.
I'm really frustrated with the tractor running like crap. I'm open to suggestions. I do have a pair of Briggs and Stratton spark testers: https://www.amazon.com/Replacement-Spar ... B01I8ALYPS I tried these today in the driveway but couldn't see crap. I think I need to try in the garage. I haven't done a compression test. I could rent a compression tester and do this.
Have you put a new kit into the carb and have you checked the intake and carb base gaskets? Are you removeing the jets to clean them and the passage ways ?
DavidBarkey wrote: ↑Mon Apr 22, 2024 6:26 am
Have you put a new kit into the carb and have you checked the intake and carb base gaskets? Are you removeing the jets to clean them and the passage ways ?image.png
This picture shows the exploded diagram .
David I removed the main jet and attempted to clean the main jet and every passage way I could find several times. Intake manifold to cylinder gaskets were replaced + I carefully cleaned both mating surfaces. The carb base and carb gaskets were not replaced at this time but were replaced in 2019 time frame the last time I pulled the carb for cleaning. The carb gasket is probably a 10 minute job... could easily try that. Carb base requires disconnecting the engine and pulling it apart. I have not put a new carb kit in. Sometimes the coils go on the Vanguards. I have not put any research into this recently.
I forgot to mention yesterday that several times when I shut the engine off it backfired. It normally does not do this. The last time I shut it down, I let it idle for 30 seconds or so and the engine did not backfire.
DavidBarkey wrote: ↑Mon Apr 22, 2024 6:26 am
Have you put a new kit into the carb and have you checked the intake and carb base gaskets? Are you removeing the jets to clean them and the passage ways ?image.png
This picture shows the exploded diagram .
David I removed the main jet and attempted to clean the main jet and every passage way I could find several times. Intake manifold to cylinder gaskets were replaced + I carefully cleaned both mating surfaces. The carb base and carb gaskets were not replaced at this time but were replaced in 2019 time frame the last time I pulled the carb for cleaning. The carb gasket is probably a 10 minute job... could easily try that. Carb base requires disconnecting the engine and pulling it apart. I have not put a new carb kit in. Sometimes the coils go on the Vanguards. I have not put any research into this recently.
I forgot to mention yesterday that several times when I shut the engine off it backfired. It normally does not do this. The last time I shut it down, I let it idle for 30 seconds or so and the engine did not backfire.
The main jet is not the only source of fuel at full throttle . The emulation tube and the thickening tube are part of the idle and mid range circuits . If these are restricted it will lean out as well . On many carbs air fuel siphon passages pass through the gasket between the top and bottom . If the gasket is no longer sealing in these areas it can also cause lean out . If your float is too low , this also will cause lean . Baddly worn throttle shaft holes will lean .
Briggs can be very finicky and a pain. They to start they are extremely under fueled and run borderline lean when in good shape and from new.... It takes very little to make them unhappy as far as dirt and or bad fuel/water etc. We have most parts in stock including new OEM carbs, pumps, gaskets etc, you are close by you could also bring it by would be glad to check it out. Posting a video may or may not help.
DavidBarkey wrote: ↑Mon Apr 22, 2024 6:26 am
Have you put a new kit into the carb and have you checked the intake and carb base gaskets? Are you removeing the jets to clean them and the passage ways ?image.png
This picture shows the exploded diagram .
David I removed the main jet and attempted to clean the main jet and every passage way I could find several times. Intake manifold to cylinder gaskets were replaced + I carefully cleaned both mating surfaces. The carb base and carb gaskets were not replaced at this time but were replaced in 2019 time frame the last time I pulled the carb for cleaning. The carb gasket is probably a 10 minute job... could easily try that. Carb base requires disconnecting the engine and pulling it apart. I have not put a new carb kit in. Sometimes the coils go on the Vanguards. I have not put any research into this recently.
I forgot to mention yesterday that several times when I shut the engine off it backfired. It normally does not do this. The last time I shut it down, I let it idle for 30 seconds or so and the engine did not backfire.
The main jet is not the only source of fuel at full throttle . The emulation tube and the thickening tube are part of the idle and mid range circuits . If these are restricted it will lean out as well . On many carbs air fuel siphon passages pass through the gasket between the top and bottom . If the gasket is no longer sealing in these areas it can also cause lean out . If your float is too low , this also will cause lean . Baddly worn throttle shaft holes will lean .
I ordered a new carb gasket, carb to intake and carb to air cleaner gasket (I know this isn't part of the problem but I might as well replace it while its apart). I might try to check for gasket leaks with a can of carb cleaner. I haven't tried this but there are plenty of how-to videos.
CaseIngersollNE wrote: ↑Mon Apr 22, 2024 10:48 pm
Briggs can be very finicky and a pain. They to start they are extremely under fueled and run borderline lean when in good shape and from new.... It takes very little to make them unhappy as far as dirt and or bad fuel/water etc. We have most parts in stock including new OEM carbs, pumps, gaskets etc, you are close by you could also bring it by would be glad to check it out. Posting a video may or may not help.
Thanks Ryan. I may take you up on your offer if I can't get it resolved. We have an ultrasonic cleaner at work I could try cleaning the carb in.
I replaced the carb gasket this week and also shot some carb cleaner through the various holes in the carb while I had it apart. The pilot jet was nice and clean. Still lacks power. I tried adjusting the carb a bit. I left it a tad richer. Towards the end of the carb adjstment procedure, there is a step to hold the throttle linkage against the stop and adjust for 1200RPM. Previously I had used 1600RPM from a post on the old forum by Bob MacGregor. Changing the stop back to the recommended 1200RPM brought back some minor surging at idle. 1600RPM basically masks the problem. I also made some minor governor adjustments to make the engine idle in the 1750RPM range as per the service manual. Still lacks power. Spark looks ok with my spark testers. I pulled the carb cover off last night, opened the anti-fire solenoid and shot enough carb cleaner through the main jet that I filled the carb over the jet. I let it sit for a bout 15 minutes before cleaning out the carb. Seemed to run ok at mid throttle today putting on fertilizer but with some minor surging at idle. Sounds like I'm taking the carb off again We do have a new ultrasonic cleaner at work I may be able to soak the carb in.
Matt , did you ever check your float height ? If too low it will also cause to run lean .
Have you checked compression ?
Have you tried a different set of spark plugs ? I know they are long life but that doesn't mean they can't go bad .
Spark plug colour . What does it say ?
Maybe more than one thing is going on .
Away to prove or disprove lean condition to add a small amount of propane while under a load add some extra fuel and see if it improves . To do this , take a standard soldering bottle . Remove the flame tip from the valve and attach a piece of hose over the tube long enough to go into the breather while you are sitting on the seat . Get out and load it up , then crack open the propane bottle a little . If it is lean , it will come to life . If is something else it will run to rich like on choke .
DavidBarkey wrote: ↑Mon May 06, 2024 6:52 am
Matt , did you ever check your float height ? If too low it will also cause to run lean .
Have you checked compression ?
Have you tried a different set of spark plugs ? I know they are long life but that doesn't mean they can't go bad .
Spark plug colour . What does it say ?
Maybe more than one thing is going on .
Away to prove or disprove lean condition to add a small amount of propane while under a load add some extra fuel and see if it improves . To do this , take a standard soldering bottle . Remove the flame tip from the valve and attach a piece of hose over the tube long enough to go into the breather while you are sitting on the seat . Get out and load it up , then crack open the propane bottle a little . If it is lean , it will come to life . If is something else it will run to rich like on choke .image.png image.png
David I have not checked the float height. My float is all plastic. Some were plastic with a metal tab where the needle hooks on that could be bent to adjust the fuel level. The fuel level with the float removed is a good half inch high, above the main jet. The service manual does have a procedure to check the float height with the carb removed. I can do that when the carb is out.
@ the one on the left in the first pic is looking lean . I read somewhere that the Kohler and B&S twins have a lean bank and that the jet on one side is a half size larger and not to get them mixed up when redoing the 2 barrel carbs .
DavidBarkey wrote: ↑Tue May 07, 2024 6:28 am
@ the one on the left in the first pic is looking lean . I read somewhere that the Kohler and B&S twins have a lean bank and that the jet on one side is a half size larger and not to get them mixed up when redoing the 2 barrel carbs .
Yes the 21HP and 23HP engines had 2 barrel carbs with two different sized jets. I've only got one Jet.
I'm going to pick up a compression tester and do a compression test in the next few days. Not sure what I'm going to get since the vanguards have a compression release and apparently there is no published compression spec.
DavidBarkey wrote: ↑Tue May 07, 2024 6:28 am
@ the one on the left in the first pic is looking lean . I read somewhere that the Kohler and B&S twins have a lean bank and that the jet on one side is a half size larger and not to get them mixed up when redoing the 2 barrel carbs .
Yes the 21HP and 23HP engines had 2 barrel carbs with two different sized jets. I've only got one Jet.
I'm going to pick up a compression tester and do a compression test in the next few days. Not sure what I'm going to get since the vanguards have a compression release and apparently there is no published compression spec.
Compression test numbers were 138PSI right hand side from the seat, 136PSI left hand side. Both plugs were removed for testing.
DavidBarkey wrote: ↑Tue May 07, 2024 6:01 pm
Matt , what kind and brand of fuel are you using ?
It's got 87 octane in it right now. I had some 109 octane, ethanol free mixed in with the 87 plus some sta-bil fuel stabilizer over the winter. I've run several gallons through since the winter. I just picked up a fresh tank but have not run any through.
DavidBarkey wrote: ↑Tue May 07, 2024 6:01 pm
Matt , what kind and brand of fuel are you using ?
It's got 87 octane in it right now. I had some 109 octane, ethanol free mixed in with the 87 plus some sta-bil fuel stabilizer over the winter. I've run several gallons through since the winter. I just picked up a fresh tank but have not run any through.
DavidBarkey wrote: ↑Tue May 07, 2024 6:01 pm
Matt , what kind and brand of fuel are you using ?
It's got 87 octane in it right now. I had some 109 octane, ethanol free mixed in with the 87 plus some sta-bil fuel stabilizer over the winter. I've run several gallons through since the winter. I just picked up a fresh tank but have not run any through.
Does your carb have the anti-diesel solenoid ?
Yes it does and it moves in and out when the ignition is turned on and off.
Does it snap back hard when key is turned on ? Is it coming all the way back ? You have cleaned the jets so many times with out a lot of success , I am thinking there is something else going on . It is hard from the other side of the computer screen to tell what is going on. Another thought is that these things are jetted on the lean side to meet emission standards that the slightest thing can become an issue . I am wondering if you have a little ware in the throttle shaft adding a little bit of unmetered air leaning it out further . If you can get a rebuild kit with new jets in it and open them up one size with torch tip cleaners or number drills . Saving the originals in case it doe not fix it . This is something I have done in the past with carbs set so lean .
DavidBarkey wrote: ↑Wed May 08, 2024 8:37 am
Does it snap back hard when key is turned on ? Is it coming all the way back ? You have cleaned the jets so many times with out a lot of success , I am thinking there is something else going on . It is hard from the other side of the computer screen to tell what is going on. Another thought is that these things are jetted on the lean side to meet emission standards that the slightest thing can become an issue . I am wondering if you have a little ware in the throttle shaft adding a little bit of unmetered air leaning it out further . If you can get a rebuild kit with new jets in it and open them up one size with torch tip cleaners or number drills . Saving the originals in case it doe not fix it . This is something I have done in the past with carbs set so lean .
David I appreciate your help
The anti-fire solenoid does snap open and closed. It opens enough that I can try to squeeze the red tube on my carb cleaner can into the jet.
I have not removed the idle mixture screw or welch plug for cleaning.
I have also read that the vanguards typically run on the lean side and the slightest bit of crap in the carb can cause issues.
