74 xs650 won't low idle and runs rough

[OwenD]

Hey Fellas,
I have been reading throughout this forum for about a month now and I haven't been able to find my issue listed. I have checked the carb guide and read through most threads. I am not very mechanically inclined so please break down your answers. I purchased a 74 xs650 with only 6,100 miles on it. Its a very clean bike. It was left sitting for almost a year with some gas in the tank which caused rusting. I have fixed the tank, replaced the oil, cleaned the points, and had an electric issues that wouldn't let the bike run. This too has been fixed. I have placed in-line fuel filters and cleaned the carbs 4 times (usually they seem perfectly clean but I still take them about and hit them with some carb cleaner). The bike will start with a kick or the electric starter and a little throttle. But sometimes when you shift into first it will die, not usually though. However after a minute of riding the bike won't maintain an idle and will die when coming to a stop unless you rev it. Also it lurches when going down the road if you give it more throttle it normally will stop. So it seems like it is starving for gas? Its at the point of playing with it I'm deciding on just getting a performance carb. Any insight will be great. Thanks again.

 

[XSLeo]

Dirty idle circuits in the carbs. With the float bowl off, air cleaner off, take out the idle mix screw.
Use spray carb cleaner in the hole the mix screw was in. Use the red tube Cover the area around the tube so extra spray won't come back in your eyes.
Spray should come out the passage above the pilot jet and all the tiny holes above the throttle plate. If not they need more work.
Spray into the passage above the pilots and it should come out the mix screw hole and the tiny holes above the throttle plates.
I use the wire quick tie off a loaf of bread, strip off a 1/2 inch or so of the cover. This exposes a tiny soft wire. Use this tiny soft wire to probe the tiny holes above the throttle plates an the passage above the pilots. Use it to probe the pilots as well.
It can often take many times of removing the carbs before you get all the crud.
Leo

 

[shade]

I found that I wasn't getting my carbs clean enough until I started blowing them out with a compressor. It took many cleanings to get them right, but at least you get better and better at it each time. Listen to the experienced guys on here, they know what they are talking about. How did you get the rust out of your tank, and are you sure it's all out?

 

[OwenD]

Thanks guys, I did take the mix screw out last week and it was pretty filthy but I will try the bread tie idea. As for the tank I used play sand and distilled water and shook it for about 30 minutes. That removed the heavy rust, but in the end I took the tank to a shop, however you could probably order an acid kit yourself and save some money.

 

[shade]

I've done 3 gas tanks over the past few years. The elctrolysis method worked great but the Krud Kutter (phosphoric acid) method was simple and very effective.

 

[fredintoon]

Hi Owen,
you don't need performance carbs, you need clean carbs and your symptoms say yours ain't.
Take them completely apart.
Except the butterflies and butterfly shafts, they are a right swine to remove and a stone bitch to replace.
So don't soak the carb bodies in any fluid that dissolves rubber.
You don't want the aggro associated with changing those butterfly shaft seals, eh?
Use a big ol' cafeteria tray to work on the carbs so you don't lose any of those little parts.
Spray carb cleaner through every hole, jet and passageway until each hole you squirt down blows out some place else.
Reassemble and test run.
Be prepared to do it over.

 

[Stoop22kid]

Check your intake boots and make sure they aren't cracked. That's what happened to mine and I was having the same problem. If they are cracked take some clean nail polish and cover the cracks until you can buy replacements