i give up

[Quinn]

whats up guys, i am giving up. i cant get this frigin 79 running, it runs for 5 mins then cuts out . i have cleaned and rebuilt the carbs replaced the manifolds, adjusted the floats numerous times swapped tanks. i just dont know what to do . it starts up idles runs and gets hot then backfires a little and stalls out, it then takes a bunch of kicks to restart only to stall out again even quicker. it starts up every time after it cools down then craps out. the electrical system is good. has any one run into this before. when adjusting the floats i noticed a running difference, lean rich but no mater what level it is at it gets hot and dies, i am almost positive it is fuel related but i just cant figure out what. what level should the c clip on the big needle be at. the more i work on this the more i get confused and second guess myself, help. i almost want to just give up on thes carbs and buy new ones, but if i do that and it still dies out i will prob kill myself and my wife does not want that to happen . please help me

[jay760]

does it die after you take the choke off,have you checked the colour of the plugs,check the inlet manifolds for leaks.

[Quinn]

we replaced the manifolds last night, plugs seems fine i cleand them ff to, going to try to swap tanks again, although my tank is a 81 single petcock, so i just have to tee it off. it is prob something really stupid. but i must say this has been a great learning experience.

[oldskewl]

did you check to make sure you have a good fuel flow ? (not restricted)
check compression with a guage ?
is that points or electronic ignition ?
is it charging ?
did you try choking it ? ( not with your hands )

[mseriously]

Have you checked the coils? I had an old dirt bike that did the same thing...got warmed up and would die. It turned out replacing the coil did the trick. Was getting a bad reading using a meter.

[jay760]

When you cleaned the plugs off were they black,could be your chokes,do you still have a spark when it dies before it cools down

[drooling-bloodhound]

If you list your model ignition, carbs and exactly what you did it would be easier to help.

[StrayKaat]

I see some good ideas. Here's one.
When I bought one of my XS650's it would cut out and die. It did this every mile or two on the way home. After sitting for a few minutes it would re-start and go for what seemed like less distance every time. My buddy who was following me suggested we stop at a mechanics garage we were going to pass anyways. We stopped there and after what we thought was a very thorough examination he couldn't find anything wrong. After it happened a couple more times on the way home I noticed something. Yes I had checked the fuel level but had failed to notice the rushing air sound when I popped the gas cap until I was grasping for straws. After I noticed it I left the cap open and continued the last 15 miles home without a hic-up. I was going through the wind when it happened each time so I didn't notice any high heat issues.
I took off the cap and soaked it in gas overnight and blew through the vent hole with compressed air. The cap was full of light rust that had probably accumulated from sitting for years with condensation forming at the top of the tank. If I had been sitting still I might have noticed high heat from the lean condition that would have occured while it was slowly starving for fuel.

Definately worth a try. I would probably run it up and down the road in front of your house. These things are air cooled and need to be moving so they don't overheat. We all know that the head gaskets on the XS650 are the achilles heel when it comes to oil leaks so I wouldn't recomend overheating the bike running it in one spot.

Good luck and hope it's something simple!


StrayKaat

[skateboardkid]

If it's cuting out after a certain amount a time I don't think it's a fuel issue. Nothings changing in that amount of time unless you just run out.. Haha. It sounds like it might be a timing issue if the bike isn't idleing right from the get go..

[igya]

Coils expand when they get hot. When there's a break in an interior wire, the heat expansion separates the break, and when they cool down, the break closes up and.............................well, you know the rest of the story.