Suzuki Vinson Carb issues

I'm working on my brothers' 2002 Suzuki Vinson 500 . It sat for a few years before I got into it. I'm concentrating on the carb - I replaced orings, needle, etc. and soaked jets, bowl and anything that I could get off the carb that the solution wouldn't eat. I also removed the tank and flushed it with hot water - it's clean. The gas cap innards rusted away and the tank had a lot of rust and water in it before I cleaned it. I replaced the gas cap and installed a new fuel valve because the screens were broken in the old one. The bike will run but spits and sputters and backfires. If you "open it up" it falls on its face and stalls - but starts right up. Here is a link to an exploded view of the carb: Ohio Honda Yamaha Motorcycle ATV Dealer - J & J Motors - Kawasaki Suzuki Scooter Utility vehicle, parts, accessories, apparel
Can anyone point me in the direction of the problem? It may still be a "clean carb parts issue" . My problem is that the parts list doesn't identify the parts to a degree that I understand. If you said" look at the pilot jet", I'm not sure which jet that would be....See what I mean? It'll run very good if I remove the air filter and cover the opening with my hand and part my fingers a little for the air to get in. Any help is greatly appreciated.
Thanks in advance, Jim

It sounds like the carb is to lean of mixture. your start idle air screw is probably not set correctly. I would start there.

Your Friendly Neighbourhood Mechanic :)

I agree that you have a bit of a lean condition. I think that is because the jets are still partially clogged, you need to physically poke the jets out with a pin or something, torch tip cleaners work very well. Soaking the parts in cleaner doesn't always cut it. I would also take the pilot screw out completely and make sure that circuit is clean and clear as well, you can blow compressed air through all of the passages to make sure they get clear. Make sure to get EVERY passage in the carb, a clogged hole anywhere can hurt the performance of the machine. The parts list that you provided the link for has a # pointing to each part, and if you reference the list below, it will tell you what part is associated with each #, for instance, the pilot jet is #9, the main jet, #8. However, you don't really need to know what each thing is, the best thing to do is take EVERYTHING apart, physically clean each individual part, and clear out EVERY hole, then put everything back where you found it. When you are done, set the pilot screw (which is concealed by a plug BTW) at about 1 1/2 to 2 turns out from the fully seated position. Start the machine, turn the screw in until the machine begins to stall out, then back the screw out until you reach the point at which the machine idles at the highest RPM. If needed, adjust the idle afterward. The idle adjustment is labeled # 26 on your parts list. Good luck.

I have a 1996 king quad with simliar issues and carb is very similiar, mine will not idle and backfires a bit, have done carb rebuild, clean out pump and installed fuel filter, new gas, checked all ports with comp air, new plug, oil change. found petcock leaking into vacuum line, plugged off port, runs a bit better but idle is still an issue, tried setting the idle screw, but either is too low and stalls or too high and keeps engine rev, is there another adjustment that may be finer to tune it?

thanks

I put my thread post of the whole job.

I got a 2004 Vinson about a year ago, it had set for over a year and it had the same problem you described as well. After I used carb cleaner and Sea Foam it would idle and run a little bit, but like you said, "It'll run very good if I remove the air filter and cover the opening with my hand and part my fingers a little for the air to get in." I did the same thing and mine would run great, so I took a sponge applicator, the type that comes with car wax and partially covered the air intake snorkel under the seat and with a little adjusting on the opening with the sponge applicator my Suzuki Vinson will run like a scalded dog. I Know this is not a fix, but a work around, I'm sure some jet is partially plugged or the throttle valve (carburetor slide) or diaphragm is not working properly. Some day when I get the time I will pull the carb and fix it. Let us know if you find out what is causing the problem. There have been others with same condition.

My 2002 has a similar problem, It idles fine when it's warmed up but it's a pain in the butt until its warm. Very speratic idle. It will run up too around 2500 rpm then fouls the plug if I leave it to idle out of gear. The choke doesn't seem to make any difference. Other times it acts normal and it runs like a champ. Tells me it's a dirt issue.I'm almost positive its a carb issue. After the snow is melted the carb is certainly coming off and being cleaned! I was going to go as far as pulling the jug and re-ringing it but the compression is very good.( just over 1K miles.) Last compression check showed 180, engine warm. Last plug I changed looked NASTY! Way rich and possibly oil fouling as well. I'll tear it down as far as I need depending on my budget....wich sadly is slim right now. I feel your pain man.

My 2004 Suzuki Vinson 500 cc sat for 13 months. The carb was cleaned thoroughly and the gas was changed. It start right up but idles rough and backfires occassionally. Does anyone know how far to back off the idle screw and the how far to back off the air screw.

i had the problems that you are describing. on my 99 king quad, at first i thought it had to be the carb. then i found out that the diaphram on the Petcock was broken and leaking into the vacuum into the carb causing it to spit and rough idle. i notice i was sucking in gas because the oil sight went from middle to full after cranking and idling for a bit. also make sure its new gas. also check the choke cable and spring. don't completely seal the tank. it needs to be vented, or else you suck in gas create a vacuum in the tank and can't enough fuel when needed.

Originally Posted by novak6931 My 2004 Suzuki Vinson 500 cc sat for 13 months. The carb was cleaned thoroughly and the gas was changed. It start right up but idles rough and backfires occassionally. Does anyone know how far to back off the idle screw and the how far to back off the air screw.

First, I will point out that the pilot screw on a four stroke meters the fuel not the air in the pilot circuit. Therefore, it is more of a fuel screw than an air screw, but it is mostly referred to as the pilot screw. The screw is used for metering air to the pilot ciruit on a two stroke, that is where the term air screw comes from. This is pertinant because, turning the screw does the opposite thing on the different carbs. On a two stroke, turning the screw in makes the pilot circuit richer, turning it out makes it leaner. This is opposite on a four stroke, since you are metering fuel, turning the screw in makes it leaner, turning it out makes it richer.

Next I would ask what a thourough cleaning of the carb means to you? Did you take EVERYTHING apart and clean all the holes and passages? If not, then I would say that you need to clean the carb out again. If you did actually get everything out of the carb, and you just need to get it tuned back to where it is supposed to be, then... Start the enginge and let it warm up, adjust the pilot screw in untill the machine starts to run very poorly, then begin to turn it back out. Keep turning the screw out until to the point at which the machine idles highest. Once you have done that, you can adjust the idle screw to where you like it. Hope that helps, and good luck.