Bringing a 1979 XS650 Special back to life

[BostonBiker]

I just got my first bike...a '79 XS650 Special. It hasn't been run in about a year but is in pretty good shape.

Made my first mistake by not draining the old gas out of it before running it, had less than a gallon of old gas so my thinking was to run it through diluted by a full tank of regular gas...it run okay so I rolled with it, but after a few tanks worth my goodluck seems to have ended.

I can barely get it to start now and it when it does it seems like as soon as the engine is warmed up it stalls out...I know that I probably need to clean the inside of the tank because I can see that it isn't as clean as it should be, but what can I do to get the bike back running without doing something drastic and costly?

Would running something like Lucas cleaner through it help? I'm really just looking for some advice on getting an old bike running while trying to avoid removing the carb or taking it to a shop...I know that may not be possible at this point. I love my 650 and want to take it cruising again before the summer ends!

Thanks!

 

[kaboom]

I'm thinking a good carb cleaning is in order....Change or clean the fuel filter.....

Check for fouled plugs....bad wires.....

 

[stuntdouble]

I second kaboom, chances are that from the bike sitting with gas in it that the gas had turned to sludge and now worked its way into the carbs and gummed everything up. clean the carbs and if you know how you should probably rebuild them. definitely drain the fuel and give the tank a good douche. check plugs and wires and replace as needed.

 

[gggGary]

Too late to avoid cleaning the carbs. Dump all the gas (crap) out of the tank. Remove and disassemble the petcock, clean the screen, replace fuel, vacuum lines. Clean carbs watch for leaky floats. There are a lot of passages in BS38 anyone of them can make for poor running if clogged. Check your battery voltage. More than one carb problem was found to be electric. Always check alternator brushes on a new to you XS650. Do this all at once in your well lit garage or learn to hate a poor running bike.
Oh I see you didn't want to do what it takes to make an old bike run well. I am sure it will understand and self cure if you ad some "magic run" to the gas tank instead. Sorry but I have been there near countless times, the easy way out "almost" never is. I started working on a "used to run" 80 special today, I started with front brakes then a new battery and cleaning all electric connections I can get to. Tomorrow pull plugs, check spark, drain the gas, smell the oil (Leaky carbs break engines) Clean tank and petcock then do the carbs. anything else is a boatload of frustration. Even with all that my test run area is uphill from my driveway till I am pretty sure it is running good.

 

[Stone]

damn you made it through a few tanks of gas...i didnt even make it through half a frickin tank not to mention wiring was not the previous owners strong suite...

 

[XSLeo]

You say you deluted the old gas with regular gas. Thats two mistakes in one shot. Running old gas and using regular gas.
You should have drained the old gas and used it in a lawn mower you don't like. Refill with at least 91 octane, 93 is better.

 

[gentlemanjim]

Well its worth a try. Change the fuel filter and put in a big slug of Techron fuel system cleaner. If it ran ok for a while it may be just some minor crap in the carbs. I'm not saying the full monty is not in order, try this first - $ you'll be out about $8.00 and it will still due some good.

 

[gggGary]

I am normally a give it a try kind of guy but I am very leery of running a brass float carb till I KNOW they don't leak. I have opened up 5 sets of brass float XS650 carbs this year 3 had a leaky float. Running an engine with gas washing off the cylinder walls is not a good thing.