I left it parked too long - now it won't run

[Titan]

I really screwed up. I haven't ridden in several months but did add Stabil to the tank when I drove it last. So, last weekend I got it out, started it up, and found that it runs very badly. I poured a can of Seafoam in the tank, went to a station and filled it up with Ethanol free gas, drove it around for about 50 miles, and it wouldn't clear up.  It's missing on at least one cylinder and possibly more. No power, and backfires like crazy when decelerating. I hoped it would unclog whatever is clogged up after sitting for a week. Went out just now, started it up and it's still screwed up. It starts easily and idles fine. But, give it a little gas, or a lot, and it's missing so bad that it makes the engine clunk.

I thought maybe a plug is fouled but I haven't pulled any of them. Wanted to ask you experts what you think is the problem. I'm not a mechanic so if it's more than plugs I'll be taking it to the shop.

[ValkISDan]

Most likely your carbs are gummed up and need to be cleaned and synced.

[Patrick]

Sounds like the classic varnished low jet syndrome. Was the Stabil completely mixed with the fuel and ran until it got thru the carburetors ? Regardless, completely mix the Sea-foam or B-12 with the fuel and run the bike for several tanks at low engine speed. Start out at around 2500 and keep lowering the engine speed until it'll run smoothly at 1500 or lower.
Also make sure all the vacuum lines and caps are in good condition.
If that doesn't work, then its time to get your hands dirty and do some cleaning.

[Titan]

Right now it basically has a full tank with a full can of Seafoam. It was only drive about 50 miles after filling it. Should I add more Seafoam or any other strong additive to try to dissolve it or just let it sit and idle with what's in it?

[old2soon]

First get all the old gasoline out of there. The old gas is part of the problem. Fresh gas and B-12 Chem Tool. RIDE SAFE.

[Grandpa dude]

since you had the stablizer in the tank, and then added seafoam... the chemicals might have had a fouling effect on the plugs... before you try to clean the carbs... change the plugs and if possible go to a bit hotter plug...and try to ride it hard... just a thought... remember, you got 6 of them, and the possibility of fouling is greater, especially since it sat.

[Titan]

since you had the stablizer in the tank, and then added seafoam... the chemicals might have had a fouling effect on the plugs... before you try to clean the carbs... change the plugs and if possible go to a bit hotter plug...and try to ride it hard... just a thought... remember, you got 6 of them, and the possibility of fouling is greater, especially since it sat.

I only added the sea foam after I drove it about 10 miles when I first started it up. So it was munged just from sitting. Good advice on draining the old gas. I hoped that filling it with new gas would have freshened it up enough to overcome the old. Im gonna go ahead and pull the plugs to see if any are fouled. My best guess is that one or more carbs got gummed up from sitting.

You know I'm really kicking my own ass for letting this happen! There wasn't a darn thing wrong with it and I know better than to do this. I have pretty much stopped riding and was planning to sell it. So I guess I just got complacent and didn't tend to it as I should have. 

[Patrick]

Don't let it sit and idle, ride it and ride it as previously stated. When adding the fuel cleaner, add the gas last so everything is completely mixed.

[Titan]

Well, it's not the plugs. They're in excellent shape.
I'm feeling like it's a vacuum line somewhere due to all the popping on deceleration. It even pops some when you're sitting still and gas a little. But the backfiring is terrible when letting off at speed and it's on both sides. Wouldn't a vacuum leak be more likely to be the issue than a stopped up carb jet?

Only visible thing I can see that I shouldn't be seeing is a connection directly behind the key switch. The clamp is easily spun around with the fingers. But I believe that's a gas line and a leaky gas fitting wouldn't cause all the ruckus.

[Patrick]

There is either a vacuum line or a vacuum cap on the back side of every intake runner. If they have not been replaced in awhile, it's overdue.

[Thunderbolt]

Might as well bite the bullet and take the carb bank out and clean the slow jets.  Change the small vacuum lines on the side of each carb while you are at it.

[Denny47]

I agree with Patrick. Also if you have any mice where you store the bike, they might have chewed thru a vacuum line or plug wire.

[heavyd]

Mine did that the first ride this spring when I was trying to limp it to the mechanic for it's yearly inspection. Made it about a km before my brain finally started firing and I remember to turn the gas back on. I neglected to mention that to my mechanic though. lol.