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Joe J
New member
Username: Jjconst07
Post Number: 8
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 09, 2008 - 08:16 pm: | 
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The 18 hp motor on my 98 Bigfoots carburator, when idling, smells so much like gas, like its running really rich, I dont get the smell as much when out driving, but I just purchased this Argo, and am still new to the vanguard motor and what makes it tick. I went to the service forum, printed out the directions on doing a basic carb clean, did that, after that, it still runs the same, very " half burnt gas smell " Also, when idling and you turn the throttle there is a quick bog down in the engine, then she'll take off like it floods for a second, my question is: is there an adjustment screw to change this? or am I in need of a full carburator rebuild? or is there some other trick that one of you knows about. I turned up the idle so it doesnt quit when at idle, but its up just high enough so when in gear, she will go a little instead of idling and just sitting still.Thats about all I have to tell you, please help? |
Jerry Nuss - Illinois MAX dealer
Senior Member
Username: Jerrynuss
Post Number: 617
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 09, 2008 - 10:57 pm: |
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Did you adjust the idle mixture screw? It is lower down towards the center of the carb on the pull start side of the engine. |
L.A. Philip Osborn
Advanced Member
Username: Roadwolf
Post Number: 147
Registered: 02-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 10, 2008 - 10:47 am: |
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Joe, Install new spark plugs, as they foul easy, engine runs so smooth, it is very hard to determine if it is only running on one plug or both, Hope this helps
Phillip Osborn LA |
Jerry Nuss - Illinois MAX dealer
Senior Member
Username: Jerrynuss
Post Number: 618
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 10, 2008 - 11:27 am: |
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Like Philip wrote check the plugs. I always check the plugs first especially this time of year and just naturally assume everyone checks the plugs. He is correct if you have not checked the plugs check them. I always have a spare pair handy. Good advice Philip! |
Joe J
New member
Username: Jjconst07
Post Number: 9
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 10, 2008 - 06:06 pm: |
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Thank You!
I will replace the plugs just to be safe, seems like good preventative medicine. It has warmed to a balmy -9 degrees here in in tropical Minnesota, so I believe I will try it when we at least get into some plus temps. After that if it still seems a bit off, I will try the idle adjustment screw. Thank You again. |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 10
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 11, 2008 - 12:59 pm: |
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My 2001 bigfoot does the same thing. I have tried everything. Mine seems to be mostly the back cylinder flooding. How can the back cylinder flood and not the front when they are hooked to the same intake? The spark seems fine. I have managed to compensate for this issue by running hotter spark plugs. I run NGK FR45. I have been running these plugs for 2 years and have had no fouling issues. It still burns rich at idle and bogs a little when taking off. I have wrote about this in the past and many other people have this same issue. If i can find my old post, I will post it again. |
Joe J
Junior Member
Username: Jjconst07
Post Number: 10
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 11, 2008 - 10:09 pm: |
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Thanks Mike, if you do find the old post I would love to see it and the answers you recieved. Tonight I took out the plugs and cleaned them, and like yours, the back cylinder seemed to be the worst of the two, it seems to run great, I hit the key and she fires up, but it drives you crazy when you hit the throttle and it bogs a little before it takes off.You say it still bogs, after installing the NGK's, did the bogging seem better, or was it the same ? |
Joe J
Junior Member
Username: Jjconst07
Post Number: 11
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 11, 2008 - 10:15 pm: |
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Jerry, if your still following this post, I was looking at the side of the carb for the idle mix screw, I didnt take off the little metal screen thing thats there yet, but is the screw your talking about a black looking thing that you can actually adjust by hand roughly a half a turn right or left? More towards the bottom center of the carb on the pull start side? or is it a screw more in the center of the carb that you would need a screwdriver to turn? I couldnt actually see the center without removing that shield thing and didnt have the time tonight. |
Jerry Nuss - Illinois MAX dealer
Senior Member
Username: Jerrynuss
Post Number: 619
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 12, 2008 - 02:10 am: |
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It is the black plastic piece. That is very restrictive so on some machines I use a pair of pliers and pull it off. There will be a metal knurled piece under it that you can turn. In your case if you are running rich you may not need to remove the plastic piece just turn it clockwise. The plastic cap limits the range it can be adjusted and they are normally a little lean from the factory. I normally take the black metal shield off and leave it off. |
Rogersmith
Advanced Member
Username: Rogersmith
Post Number: 361
Registered: 01-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 12, 2008 - 02:45 pm: |
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Yep leave it off for idle screw access. And when doing the carb cleanout, pull this screw and spring out and put cleaner and compressed air though it also. Screw it back in, seating it gently, then turn out.. oh 1.5 turns. Start engine and adjust from there. The fastest idle you get from adjusting this screw will be a little lean, so unscrew another 1/4 turn or so. Out,(richer) will help the acceleration stumble. But no more out/rich than necessary. |
Joe J
Junior Member
Username: Jjconst07
Post Number: 12
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 12, 2008 - 06:44 pm: |
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Thank You, I look forward to coming home from work just to read your responces, everyone is so helpfull here, I really appreciate it. I will play with that adjustment later in the weekend, I am taking the family up to our cabin, 5 hours north of here near Ely MN, there is no access to the cabin during the winter months, the 40 acre piece is within ( surrounded by ) Superior National forest, on the road we drive in on during spring, summer and fall, is now maintained cross country ski trails. We park at the boat landing and walk the half mile across the lake ( we only go up a couple times during the winter). This will be the first trip across the lake in the Argo,( 36 inches of ice ) and saturday night they are predicting 27 below zero. Since the Argo bogs a little but runs well, I wont attempt any adjusting till we are home safe and warm : ) Thank You again. |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 11
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 13, 2008 - 05:18 pm: |
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Joe, My machine still boggs a little witn the NGK's, but I know how to feather it on the start until it takes right off. What I'm finding on my machine, is that if i take off the air cleaner and make it bogg, gas blows out the top of the carb. My therory is there is an exhaust restriction on the back cylinder. At low RPM it has a hard tim pushing the exhaust out, and when you goose it, the exhaust is blowing bach thru the intake valve. The only way to prove my theory is to take off the muffler and run it for a minute. I haven't had time. Since i started using the NGK hotter plugs, it works, so it hasn't been a priority. but the root problem is still there. I've monkeyed with every carb adjustment there is short of rebuilding it. My machine has done it from day 1. |
Jerry Nuss - Illinois MAX dealer
Senior Member
Username: Jerrynuss
Post Number: 624
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 13, 2008 - 05:57 pm: |
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Have you adjusted your valves? |
Joe J
Junior Member
Username: Jjconst07
Post Number: 14
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 13, 2008 - 09:43 pm: |
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My Argo also blows the gas back when I take off the air cleaner, so it seems we have the exact same trouble.... fix yours and tell me what you did. ha ha
I have no idea how to adjust the valves, I would love to learn how, they seem fairly easy to get too.
I am all packed and ready to go north in the morning, Argos on the trailer, and we are getting 6 inches of snow here tonight, should be a lovely drive.
Thank You! |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 12
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 14, 2008 - 07:26 am: |
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Joe, We are not the only ones having this same problem. I have written about this a couple of times. I've had people email me saying that they are having the same problems also. The 18 horse vanguard is in many other pieces of equipment with no issue. Everybody who has emailed me has had a bigfoot. What is the differance between equipment and a bigfoot? I haven't heard any problems with the 16 horse vanruard or any of the conquest machines. Does Max use the 18 horse? I haven't heard any issues with those machines either. That's part my reason for the exhaust theory. Does anybody know if the exhaust system is different between a bigfoot and any other argo? |
Eddie L. Beddingfield
Advanced Member
Username: Argo2003
Post Number: 105
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 14, 2008 - 07:27 am: |
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Briggs Vanguard engines,pull the plugs and both valve covers off.Using a pencil stick it into first cyl..Roll engine to TDC,Then roll engine 1/4 past TDC by watching pencil traveling down.Adjust both valves to .005 clearance. You will need a 10 mm socket to get off valve covers,also a 12 or 13 mm wrench for the valve locknut,then a metric allen(forgot the #) to adjust valve.Do both cylinders (Note,Error on the loose side when adjusting clearance.) |
Joe J
Junior Member
Username: Jjconst07
Post Number: 16
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 16, 2008 - 07:08 pm: |
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Eddie, Thank you, it sounds a little scary but easy once you do it I dont understand the allen wrench part, but I take it that adjusting with the allen wrench will become apparent once I get the cover off. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 76
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 23, 2008 - 07:33 pm: |
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I ran into another Bigfoot owner today out ice fishing, I'm wondering if it's the carburator on the 18HP engines that may be at fault. Same issues, gas spraying back if you take off the air filter, stumbling on acceleration and blowing a bit of soot. I added some Seafoam to the gas, I'll give it another run tomorrow and see if it helps any. Next step will be a valve clearance check, not hard going by the above directions. One thing that did amaze me was that it started without any grumbling this morning at -5F. |
Joe J
Member
Username: Jjconst07
Post Number: 23
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 03:01 pm: |
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Erich
My Argo Bigfoot seems to be a little better after I put sea foam in the gastank, I have about 3 hours runtime since I did that. I also notice that it runs better as it has warmed up outside, I had it out yesterday in 20 degree weather, and it seemed much smoother running than when it was closer to zero out. I have only had it a month, and its been below average in temps here in MN. If you do check the valves and do any changes, please post it here, I would be really curious to know what you find and how it effects how it runs. |
Peter Trusty
New member
Username: Pete6x6
Post Number: 3
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 03:53 pm: |
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Joe What is sea foam? thanks Peter |
Joe J
Member
Username: Jjconst07
Post Number: 25
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 05:52 pm: |
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It comes in a metal can, you can buy it at most gas stations here in MN, any walmart etc. it cleans the carb, removes water from the gas, its supposed to be really good, you put the recommended amount in your gas tank like you were using "heet". It says you can pour it in the oil as well for other cleaning or something, I just put it in the gas tank, I do it in the fall in my boat motors as well, it also acts as a gas stabilizer. |
Marc Stobinski
Intermediate Member
Username: Jerseybigfoot
Post Number: 60
Registered: 06-2000
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 07:18 pm: |
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I have a 2004 bigfoot and my buddy has a 2002. The 2002 hesitates and sometimes stalls. setting the idle mixture rich helps but is not a cure. the 2004 is much better and only has the slightest bit of hesitation off idle. Has anybody checked if it a function of the governor spring position, since the throttle pulls on the govenor linkage not the carb. On the 2002 it seams like the throttle butterfly opens 100 percent when you crack the throttle. Both machines are at my friends house along with a Max and a ATTEX with 18 Briggs. When I have a chance i will post the spring and governor set ups of all the machines. |
L.A. Philip Osborn
Advanced Member
Username: Roadwolf
Post Number: 151
Registered: 02-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 08:06 pm: |
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Marc Great to hear from you.
Phllip Osborn LA |
Peter Trusty
New member
Username: Pete6x6
Post Number: 4
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 08:55 pm: |
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Joe Sounds like something good, I will see if I can get it locally Thanks Peter Trusty |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 77
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 24, 2008 - 10:37 pm: |
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Well I'll be darned, don't want to claim victory yet, but, the Seafoam does seem to have made a bit of difference, a little less hesitation and manages to keep running at idle...for now. I'm still going to check the valves this week, hopefully have the mindset to take a couple of pics. The possibilty of governor spring action may also be part to blame...we'll see the outcome. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 78
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 25, 2008 - 12:50 pm: |
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Well, took the above directions for the valve check, valve cover nuts are 8mm, when pulling the valve covers off, be carefull otherwise you'll loose the rubber backed washers down into the bowels of the engine compartment...almost lost one. Retaining nut on the adjusters are 13mm, the allen socket adjuster is 5mm. Checked all with a .004" feeler, loose, except for the rear intake, backed it off. A .006" feeler is almost tight. Unfortunately don't have a .005". This job took all of 15 minutes including the hand wash after. Started it up, still stumbles a bit, also beginning to wonder about the gas quality, I always get a bit of condensation blowing out of the exhaust at start up and for about 5 minutes. We'll see how it runs after this weekend coming. |
Joe J
Member
Username: Jjconst07
Post Number: 28
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 25, 2008 - 04:52 pm: |
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Nice post, I think I may be able to do that without too much trouble as well, but that didnt really fix your problem. The sea foam stuff should take care of any water in the gas. I hope it evens out for you and starts running better. |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 13
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 26, 2008 - 04:52 pm: |
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The governor spring position idea makes sense, but if your problem is like mine, the rear cylinder seems to be the major problem. How would the governor effect only one cylinder? I'm really courious about the max 18 horse motors. Do they hesitate when goosing the throttel? Do they blow gas out the top of the carb? Argo's have a 1 barrel carb. Briggs makes other vanguard's with 2 barrel carbs. Does max use the same 1 barrel carb as the argo's? This is a great discussion that I've been waiting on answers for the last 5 years!!!! Keep this thread going!! |
Jerry Nuss - Illinois MAX dealer
Senior Member
Username: Jerrynuss
Post Number: 639
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 26, 2008 - 07:36 pm: |
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Max does use the same carb. I have one and I am not experiencing any of the problems you have mentioned. |
Dave Evans
Intermediate Member
Username: Dozer
Post Number: 88
Registered: 01-2001
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 28, 2008 - 09:08 pm: |
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Mike I do not understand what you are describing, Please tell us again Dave Evans |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 79
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 28, 2008 - 10:14 pm: |
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Dave: He's describing the issues we (seems like a number of people) have with the B&S 18 HP Vangard engine. They don't idle well regardless of idle screw position, on accelerating, the motor bogs down, "stumbles" and quits or almost quits and blows raw gas back out of the carb. Unless the valve clearance is way too tight, I can't understand how it can spray fuel "backwards" out of the carb, doesn't make sense. I did the valve lash clearance on mine a couple days ago, almost within spec. Valve timing out maybe, missaligned camshaft? It's aggravating. I used to believe B&S motors were just about stoopid proof, but my faith in them has gone down the tubes. If I could drop a Honda 20 V Twin in there without any hiccups, I'd do it at midnight tonight, just to have peace of mind. |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 14
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 29, 2008 - 01:08 pm: |
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That's why I think my exhaust theory that I discussed before makes since. Think about this: the piston goes up on compression, comes down on power, comes back up on exhaust. If the exhaust is restricted, when the piston is coming up on the exhaust stroke, it will make compression. When the intake valve opens, the compression that was made, back feeds thru the carb blowing gas out the top of it. I think it is only happening on the rear cylinder because that is the plug that wants to foul and after running for awhile, i can touch the rear valve cover without getting burnt. If i touch the front valve cover, it will burn my hand. This tells me that the rear cylinder is not burning correctly. And, since the Max does not have this issue, it leads me to believe that the argo exhaust system on the bigfoot is causing some of the issues. The only people that i have heard of having these issues are people that have bigfoot machines from around 2000 to 2004. I would like to find out if the exhaust system is different on the bigfoot than the vanguard or responce, etc. I would love to remove my exhaust once and run it, but I'm afariad of burning a valve. I would like to hear from more people that are having this problem to try to narrow down the causes.
Thank's,
Mike |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 81
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 29, 2008 - 05:36 pm: |
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Okay, read your theory a couple times to digest it, if the rear exhaust was restricted, (causing excess back pressure and not allowing the full amount of new air/fuel mix in), would it not be right that the rear cylinder should burn lean and not rich(fouling the plug). Your comment that the front valve cover is much warmer than the rear runs true for mine too. I wonder if there would be any noticeable difference if you took the front plug wire off while running to see if the carb would still spray gas out. I don't imagine running the motor for a few minutes without the muffler would cause any damage, any comments from anyone? The miserable saga continues. |
Rogersmith
Advanced Member
Username: Rogersmith
Post Number: 364
Registered: 01-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 29, 2008 - 07:08 pm: |
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I wonder if the problem is spark, in this case the rear cylinder. That would be a wet plug and cold cylinder, and cause the wheezing out the intake.
I have a '97 argo 18hp and had no trouble at all making it run flawlessly, never hesitated, idled perfect. I had to do a few things to get it there. The carb changed internally sometime after '97, I've cleaned the bowl out on one, and seen them run bad, but not worked on them.
I would think if you can touch a cyl head and not get burned, it's not firing any. Wait a minute.. somebody refresh my memory on what the diode between the magnetos does. Allows key shut off? but if it's bad does it affect the ignition? Have to ask around. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 82
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 29, 2008 - 09:35 pm: |
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Well it's not "cold" per se, but noticeably cooler than the front cylinder valve cover(not the actual head). They both show a blue spark when checked. What I have trouble with: If both valves are closed after the downstroke(new charge of air/fuel drawn in) and the valves both remain closed all the way through compression and firing until the piston is roughly at the bottom before the exhaust valve starts to open and expell the burnt gas, where in *%#@* name does the pressure come from to "blow" or "wheeze" gas back up through the carb? I'm not a mechanic, but I've got a pretty good understanding of the mechanical ups and downs of these things, not the first motor I've threatened with a sledge hammer and got it running right. Bad valves maybe? Anyone know the spec for a compression test on these motors. This engine only has 101 hours, so it's not ancient. |
Bill Stock
New member
Username: Tripleguy
Post Number: 6
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 02, 2008 - 10:06 am: |
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My MaxII with the 18 Vanguard was doing that as well. Float level too high. Cleaned out needle jet seat and adjusted float level ever so slightly. Seems fine now. Good luck. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 83
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 02, 2008 - 02:23 pm: |
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Bill: How far did you bend the float? 16" maybe? Thanks. |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 15
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 03, 2008 - 05:40 pm: |
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I conducted a compression test last winter because I thought that maybe a valve was burnt. The compression was around 100 psi. Both cylinders were the same. Since the pressures were even, that doesn't seem to be the problem. The spark looks great on both wires. Think about this: If it was a carb problem, both cylinders would run rich since it is a one barrel carb that feeds both cylinders thru 1 intake. There wouldn't be a cylinder that runs right and one that runs rich. Like I said in eariler posts, I swithced to hotter plugs and it is definately better. It wont flood out and stall when idling any more. It just stumbles a little on take off. If it were spark, then there would not be much power on upper end. I have pretty good power when running wide open. Here is another reason i think it's exhaust: The oil smells like gas and the level seems to go up a little. If there is pressure on the rear cylinder during the exhaust stroke, it is pushing it thru the rings and into the crank case. I would like to put air pressure into the spark plug holes and rotate the engine until cylinder 1 comes up on exhaust and listen to the exhaust pipe. Then do the same for cylinder 2 and see if there is a difference in air flow thru the system. This may tell me if there is a restriction. Or I may just take the system off and run it for a minute. I would know instantly if it cured it. |
Joe J
Member
Username: Jjconst07
Post Number: 31
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 03, 2008 - 10:26 pm: |
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Soooooo close,I read this every day, and watching everyone go through their thinking process is entertainment in itself. I would never have guessed when posing this question that so much good info could come out of it, another week or two and I think someone will have an answer The only thing thats a bit sucky is Mike may have it pegged, and if you take off that exhaust pipe, and thats the problem, I will be screwed since just two weeks ago I finished the Argo exhaust heater, How the heck am I supposed to get in there and monkey with the exhaust now? Hmmm maybe another thread ha ha. That would be my luck. |
gregg g
Member
Username: Brushcutter
Post Number: 31
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 12:39 am: |
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If gas is BLOWING out of the top of the carb then it would almost certainly be a problem with valves.BUT be sure that your float is set properly so that a slightly flooding carb mixed with engine vibration doesn't appear to be gas blowing out the carb.Try a new needle and seat,carefully set your float to correct height then adjust idle mix.Fouled plugs "usually" mean bad plugs,weak spark,or flooding.On a low hour motor look at needle-seat first.What about coil to flywheel gap?Spark timing could be suspect in bog down but it would be rare,due to the way the coils are mounted,they would have to get loose and wallow the holes a big bunch to affect the timing and you would really notice this because the thing would probably sound like the pistons were swapping holes while running. Hope this helps. GG |
Joe J
Member
Username: Jjconst07
Post Number: 35
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 03:45 pm: |
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Today I took the carb apart again, and cleaned it really good, I removed the plastic piece on the idle mix screw, and played around with that, its wierd, it actually will bog down less at take off if I make the mixture more rich, which is exactly the opposite of what I was expecting, however, after you make it a little richer, then it really smells like half burnt gas, and everytime you shut the machine down, it backfires now. I have gotten to the point where I believe either a brand new carb, or maybe a carb rebuild is in order, the machine has 300 hours on it so maybe thats what it needs, its just the idea now, I will win this one no matter what is my thinking. Now my question is this, looking at that carb, it looks like it bolts from underneath, does anyone have any tips and tricks or how-to's on taking the carb off the machine ? |
Joe J
Member
Username: Jjconst07
Post Number: 36
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 03:49 pm: |
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Gregg
Thanks for the post, you bring up some interesting points. I am sure some of the gas blowback that occurs is from vibration but its certainly seems as though its simply dumping too much gas down the barrel and yes it does spray back out at you a little. How do you set the float ? |
Missouri's Max Dealer
Advanced Member
Username: Brandon_price
Post Number: 267
Registered: 01-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 04:21 pm: |
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I have had similar issues with the Briggs motor. Many times it leads you on the wrong track by making you think it is getting to much gas. More times than not, it is getting to much air and to little gas. Remember, a gas motor needs an exact air to fuel mixture of 14.7:1 to run correctly. To much or to little of either one will couse it to run poorly. An engine guru once told me that an engine blowing fuel out the carb is actually getting to much AIR, the exact opposite of what you would think. I've never confirmed that but it does seem to happen.
Most Briggs motors come with RC12YC spark plugs. The manual also recommends the RC14YC plugs, which are hotter. Those are Champion plugs. Get a new pair of those and install. Then richen the carb mixture screw by turning it counter-clockwise. I bet the motor will clear up pretty well within about 1/2 to 3/4 turn. Also, the Briggs does not have an accellerator pump on the carb like the Kohler does. Some off the line bog is normal as long as it's kept to a minimum. They are lawn mower/generator engines made to run at a constant RPM. |
Joe J
Member
Username: Jjconst07
Post Number: 37
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 09:36 pm: |
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That makes total sense, Thank you. Funny you bring up the 14 plugs, yesterday I was trying to find some ngk plugs that a former poster here had suggested, I couldnt find two of them without having to drive about 20 miles, so they gave me a champion plug, and they said it was actually one number hotter than the ngk, and the number on the plugs is RC14YC. and I will admit that did help a little. If my Argo is back fireing now at shut off, am I a little too rich ? theres a fine line in there where you cant really tell if your gaining or loosing? |
philip w.cox
Advanced Member
Username: Philipatmaxfour
Post Number: 492
Registered: 01-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 12:29 am: |
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Joe-Have you tried reving your Briggs to about half throttle and holding it there while you shut it off? That is what the manual on my wife's Briggs powered ,zero turn lawnmower says and she does it faithfully and no backfires. I forget and it backfires! Seems wrong? |
Joe J
Member
Username: Jjconst07
Post Number: 38
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 10:44 am: |
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I will try that today, my lawnmower has a 22 hp briggs, and that thing backfires since the day I bought it from the dealer, I will try it on that too. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 84
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 05:49 pm: |
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I think Missouri's Max Dealer may well have hit the proverbial nail on the head with the last line, those motors are meant to run at a constant rpm and don't have an accelerator pump, that's why they bog and snort gas. I had another older 8x8 with a Kohler twin, that motor ran like a jewel. |
gregg g
Member
Username: Brushcutter
Post Number: 32
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 09:44 pm: |
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Joe
Float height depends on engine # as follows: all engines except series 290400,294400,303400:parallel to mounting surface.On above series with fuel pump:1/16" below bowl surface;without fuel pump:3/32"above bowl surface.All adjustments are made with carb held just past vertical so that needle valve is closed.This info from the HAYNES SMALL ENGINE MANUAL.Hope this helps. GG |
Joe J
Member
Username: Jjconst07
Post Number: 39
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 10:15 pm: |
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Thank You Gregg, I will check out what number I have next time in in there tinkering.
Erich,I think your right, Missouris Max Dealer makes a good point, It still doesnt explain why some motors do it and some dont, but that said, maybe the bog I feel when I accelerate isnt that noticable to some, I dont know, and now for what may seem like a really dumb question so bear with me. Why cant a person install an accelerator pump ? or can you ? |
gregg g
Member
Username: Brushcutter
Post Number: 33
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 09, 2008 - 10:39 pm: |
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Mike
The intake valve should never be open during the exhaust stroke.Your valve timing would have to be way out of sync for this to happen and the engine would not run under these conditions.As far as the exhaust pipe restricting flow here is something to think about;the exhaust valve will begin to open at bottom dead center of power stroke,remaining so through the exhaust stroke and again be closed at tdc of intake.Although it happens way,way faster than I can type,it is still a process.Undoubtedly,removing the pipe will allow more airflow but I wouldn't think that it will change the gas blowing out of the carb problem.Has anybody tried cleaning the crankcase vents just for kicks?I don't think this will matter,but stranger things happen every day.good luck. GG |
Mike Wegener
Junior Member
Username: Wags4x4
Post Number: 16
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 10, 2008 - 10:21 am: |
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Greg,
I realize the intake valve will never be open during the exhaust stroke. What I'm saying is that when the piston is coming up on exhaust stroke it is making some compression because a an exhaust restriction. Even when the exhaust valve closes, the compression will still be in the cylinder. The intake valve opens immediately after the exhaust valve closes and when it opens the compression is back feeding thru the carb causing gas to blow back. Now this is just my theory and I know you guys wont believe it until I disconnect the exhaust and try it. I have learned to deal with it and have been getting by for 5 years by adjusting the carb to get it to run as smooth as possible and running hotter plugs to burn the rich mixture. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 85
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 10, 2008 - 11:36 am: |
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Joe J: Unless I'm off the planet on this one, accelerator pumps are an integral part of the carb and are linked together with the actual "gas pedal" so to speak. When you give it some gas, the linkage will depress a little plunger in the carb that shoots in an extra amount of gas. Otherwise all of a sudden, you open the butterfly valve to increase engine speed, it lets in extra air to get more fuel/air mix, but, it takes a second or two for the vacuum to form and suck in the extra gas from the carb and that's probably what causes the stumbing. I have tried gentle acceleration and lo and behold, no more stumbling. I guess that's one of the refinements of electronic fuel injection, instant exact amounts for what the engine needs based on load and speed. |
Dennis F. Saskowski
Advanced Member
Username: Sasko
Post Number: 170
Registered: 07-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 10, 2008 - 09:13 pm: |
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Guys, that is always a problem with carburated lawn mower type engines.Unlike carbs on wheeled machines (ex: motor cycles).We don't have transmissions to stay on the power curve for changing conditions. Our accelerator pumps only juices it up just to keep from stalling like explained by Erich.Yes both valves do stay open at the same time in a internal combustion engine ,it's called valve over lap, most evedent when acceleration is desired at a lower speed and load that the cam is not dialed in for its working rpm range.Most often what happens is that fuel is spits out of the carb(exhaust pushing it out the intake track).Now all is needed is a accelerator pump that can be dialed in to our application.Missouri max also hit it, maybe too much air.Maybe a bigger squirt of the acceleraor pump is needed. In the meantime do what Erich suggested. |
Erich Kelter
Intermediate Member
Username: Fisherman
Post Number: 86
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 10, 2008 - 09:47 pm: |
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Dennis: Thanks for the explanation regarding the valve overlap, I wasn't aware of that. So anything short of changing the cam to prevent this, I'll stick to gentle "feathering" of the throttle and live with it. |
gregg g
Member
Username: Brushcutter
Post Number: 34
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 10, 2008 - 11:10 pm: |
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Mike
An old friend of mine who was an enine machinist/builder once told me "air flow equals horsepower:doesn't do any good to let it in if you can't let it out." If he were still alive I would ask him about this.If you know the max cfm of your carb then you can through highly secret and complex mathematical computations protected under death threats by lunatic engineers figure what size your optimal exhaust would need to be.I see what you are saying and it sounds like you've got yourself a letting it out problem.Take the exhaust off if it will not get into stripped threads or anything nasty like that.I guarantee that you will notice a difference,but don't run it like that for very long.I think that some of the guys in kart racing would know exactly what to do about this and there are several books out about small engine performance tricks but I don't have any. GG |
gregg g
Member
Username: Brushcutter
Post Number: 35
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 11, 2008 - 09:49 pm: |
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Hey guys
Today I put the question to the guys in the shop where I work.Combined mechanical experience of the 4 engine builders present at the time:over 74 years.The unanimous answer-check float,needle and seat;one did mention an accelerator pump.Valve overlap-nah. |
Tristan Van Zalinge
New member
Username: Tvanzalinge
Post Number: 1
Registered: 02-2014
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 18, 2014 - 12:22 am: |
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What elevation are you at? I only ask because I was having a similar issue and I researched it a little bit. Seems where I live I needed a different fuel pump. Apparently and this is straight from argo, when you live above 5,000 feet you need a fuel pump that will apply at least 3 psi of pressure for the carburator to function properly. I am not sure how that works but I can say it worked for me. |
Tristan Van Zalinge
New member
Username: Tvanzalinge
Post Number: 2
Registered: 02-2014
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 18, 2014 - 12:24 am: |
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Sorry it's off of the subject but does anyone know where to find an argo bigfoot 6x6 cab that won't break the bank. Thank you. |
Jeff McBrayer
Intermediate Member
Username: Beemer
Post Number: 80
Registered: 02-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 19, 2014 - 11:16 am: |
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Go to your local lawn mower shop, its just a Briggs Stratton carb Jeff |
Shop Talk: Tech Tips and Q&A section