Troubleshooting help

ght58

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I have a 1982 XS650 Special w/ 16,920 mi. I believe it is all stock. The bike sat for a good 4-5 months while I was traveling. The bike is sputtering and shutting off frequently. It idles all over the place, but usually drops very low and then shuts off. I've checked the battery and spark plugs - so assuming it's a carb issue, but I have no idea - I'm just starting my learning process of how to work on bikes and assess issues.

I've added 1/2 bottle of SeaFoam to the 1/2 tank of gas that was in there, let it sit for 30 min, ran it for 30 minutes adjusting the choke to keep it on, and then drove it around for a bit - it was still shutting off when I drove it around. I then added about 1/2 tank worth of new gas to the gas/seafoam that was in there already, and have ran/driven it for 15-20 min at a time on three different occasions this past week, and I am seeing improvement in the bike staying on, but there are still issues.

The bike starts up when I have the petcock set to PRI and the choke on. I'm having to keep the choke on for quite a while, but once I get the bike running, I can turn the choke off and the bike will continue to run as long as I don't sit for too long. However, if the choke is off, the bike slowly starts sputtering and will eventually turn off within 20-25 sec of sitting.

If I have the petcock set to ON, then the bike does a much more poor job of idling, staying on and will usually shut off very quickly whether I'm sitting, driving, turning, etc.

It's been very hot (100+) for several weeks now.

Any insights would be greatly appreciated.
 
Not idling well and running only on choke or both classic gunked up carb symptoms.

After you clean a few of them and find yourself using pics and compressed air and maybe even the torch you realize that any sort of snake oil you put in the gas tank is not actually going to clean out that tiny pilot jet or much of anything else for that matter.

also there is almost invariably a bunch of sludge or powdery do or algae or you name it in the bottom of the float bowl that's just waiting to suck back up into the pilot and clogged it again so you might as well take the carbs off and clean them for real
 
Welcome to the site ght58 ! When ya do your carbs ,pay close attention to every detail ,take pics of everything before you disassemble so you know how it goes back, most importantly, read up on all the carb stuff in the tech section! This should answer all the questions your gonna have! A lot great people here that know there stuff! Send pics of your bike if ya can!
 
I really appreciate everyones comments, thank you so much for taking the time to respond and pointing me in the right direction. I'll be digging deep in the tech section over the next few days!
 
Welcome aboard. Nice to see newbies.
www.amckayltd.com/carbguide.pdf is what you need to read. It was written by the carb guru's of this site. It explains step by step on how to tear down, clean, inspect everything in there. It then explains how to reassemble with making proper adjustments along the way.
I and others would recommend not buying carb kits. Most often all you need is a good cleaning. The inspection phase of the process will identify any worn parts. no need to buy parts you don't need. The stock gaskets are very robust and can easily with stand several tear downs if your careful with them. No dealers are needed. Spray can carb cleaners work well. Canned air works well if you don't have an air compressor.
On some kits about the only parts other than gaskets you can use is the float valve. Any needles and jets are most often not the right parts.
If parts are needed get genuine Mikuni parts. They are still available. Often the same price as the cheap knock offs out there.
Leo
 
Just wanted to give yall an update and poke fun at myself a bit...I spent quite a bit of time going through all of the recommendation above, reading the guide that was provided, watching videos on youtube, etc. I found one video that took me step-by-step how to dismantle the bike to get to the carbs, so I was following that and I saw the vacuum line off the petcock was just about cut in half hahahah. I replaced that before I did anything with the carbs. I turned the bike on and it idled beautifully. Rode it around for awhile and no issues whatsoever.

That's how you learn though. I'm looking forward to learning more and working on it. I'd like to give it a good cleaning and then will make a few cosmetic changes.

Thanks again for yalls help. Good reminder to check the easy stuff first!
 
Us back yard folks aren't the only folks that have issues. I was riding one day and stopped for gas. Saw Harley over by the air hose. The women was down on the ground trying to read the side of the tire for tire pressure.
I asked what the problem was and the guy mentioned he worked in a bike shop. I scratched my head and thought a guy works in a bike shop and has no idea how much air a tire should have.
I asked if he knew that the pressure on the side of the tire was not the pressure you used to ride on but the max pressure the tire was designed to hold at the max weight listed on the tire.
Now it was his turn to scratch his head and then said he didn't know that.
I was riding my Harley that day and told him what my owners manual said about tire pressure. With a single rider cold pressure should be 30 front, 35 rear. Hot pressure should be a bit more. 3 lbs on the front and 3.5 in the rear.
With passenger the front is the same but the rear should be 40 psi cold and 44 hot.
He said thanks and aired up his tires.
I just shook my head in wonder about a bike mechanic that did even know how to air up tires.
I should have asked where he worked so I would know where NOT to take a bike.
Leo
 
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