Gas running out of Carb

[odie-in-az]

I bought an 1973 tx650 running. I began by reading my manual. I checked the idle mixture screw on both carbs and noticed they were open far beyond manual specs. I followed the manuals advise and screwed both idle mixture screws until they just seated and turned them 3/4 turn as the manual specified. Well, upon staring it back up gas began pouring out of my carbs. After trouble shooting I found out that if my left petcock is open then gas leaks out of the carb. If the right side petcock is open, and the left closed, then the bike starts, and idles with choke open, and no gas pours out. Before I screw anything up anymore can someone advise me what I'm doing wrong. I have never worked on carbs and this is my first time. I bought this bike to learn and I already have problems. Thanks for the help.

p.s. I did put some Lucas in the gas for treatment. This bike was stored for ten years properly from the buyer and has been ridden a dozen times with no issue since it was brought back to life.

 

[XSLeo]

Lets start with saying welcome to the forum.
It sounds like the float valves are dirty or the floats are stuck.
www.amckayltd.com/carbguide.pdf will help you get them figured out.
Remove the carbs, follow the carb guide to disassemble, clean, reassemble the carbs.
It tells how to tune the carbs to get them working at thier best.
Cleaning the tank and petcocks is a good idea too.
Fuel additives may help keep a clean carb clean but won't help a dirty carb much.
Tearing them apart and a proper cleaning is the best thing to do.
I might suggest reading through the XS650 TECH section found up at the top of the page. Also if you haven't already get a repair manual. It will save you a lot more money than they cost.
biker.net has them to down load but I like to have an actual book to read. I have collected all the manuals from 70-81 on Ebay. 82 up I have downloaded from The Garage Look under General Discussions, General Board, the first few threads are stickies so you can find them easy. They are links to all the Yamaha Factory Manuals.
Down load them all, they all have good info.
Leo

 

[odie-in-az]

Thanks. I'm a newb and I'm sure if I would have surfed all the threads I could have found one in this very issue. Thanks for the response and I'll give it my best!

 

[650Dave]

You might have some garbage in your tank, maybe a bit of rust even, and you might benefit from adding an inline filter for each fuel line from the tank to the carb. A bit of crud can prevent the needle and seat from sealing fuel flow properly. I have had this problem on several bikes, and the filter, while not solving the root problem, allowed me to go forward without gas pouring out of the carb(s). Dave

 

[odie-in-az]

You might have some garbage in your tank, maybe a bit of rust even, and you might benefit from adding an inline filter for each fuel line from the tank to the carb. A bit of crud can prevent the needle and seat from sealing fuel flow properly. I have had this problem on several bikes, and the filter, while not solving the root problem, allowed me to go forward without gas pouring out of the carb(s). Dave

Good advice. I will definitely look into this!