82 XS400 randomly dying, carb leaks gas if petcock left on

[eexist]

Just found this forum and I'm pretty stoked. I bought an 82 XS400 the other day and I am having a few issues. On my initial ride home the bike died randomly in the middle of a bridge..... Luckily it was later at night and there were very few people out and about because there was no shoulder. I have zero issues starting this thing up, even @ 30 degrees at the crack of dawn it instantly fires up.

Issue: Bike seems to randomly die, I will be going 35-40 mph and it will just suddenly shut off like I hit the kill switch. Once I was able to turn the petcock all the way on and it was able to start back up since I was going pretty fast. It looks like the previous owner installed a gravity fed petcock (both vacuum ports are capped off I believe) and told me to only turn it on 1/3 - 1/2 the way for cruising. If I turn the bike off and let it sit after a few minutes it will start leaking gas out of the air filters(the box is cut away, aftermarket filters attached directly to the carbs). After it dies it takes a few minutes for it to want to start back up again. When it dies the lights do NOT go out and the starter turns over fine. If I try and crank the throttle it sounds like it's really bogged down and wants to start but won't.

What should be the first thing I need to look at? Should I rip off the carbs and take them apart or is there something else I should look at. it doesn't seem like the kickstand switch would be causing it because there is no way for the kickstand to get down that far while riding. Battery terminals seem to be corrosion free and securely attached.

Thank you!
Karl

 

[rshutchinson]

Well, firstly you have a stuck float or bad float needle and seat on the carb that is leaking gas. That will be messing up the flow of the fuel into the cylinder as well since the carb bowl can't regulate the fuel level correctly.

I would take the carbs off and clean them. It's really a simple process and if you take care removing the float pins as to not break the towers off and use good fitting screwdrivers on the jets there really isn't much if anything you can mess up. Just take notice of what goes where and in what orientation. If you get confused, plenty of people here to help with how it goes back together.

Cleaning the carbs and opening the petcock fully may just fix your stalling problem but it doesn't seem to be 100% related as you say the bike dies fully as if you killed it. That seems to me like an electrical problem.

The kickstand switch could still cause that even with the kickstand not going down, that was a common problem on some GSXR's. The sensor and/or kickstand can bounce around and cause it to open the circuit. Something to look into, as well as the kill switch on the handlebar itself.

Also, when you take the carbs apart, take notice of what size jets are in it. Since you are using pod filters directly on the carbs it should have been re-jetted with larger jets to accommodate them.

 

[eexist]

Thank you for the info, I will pull the carb off tonight after work and get it apart. I'll check on the kill switch on the handlebars, would just taking off the kickstand sensor be a good option?

 

[rshutchinson]

You can, just make sure you always put it back up before taking off. I'd test it first by just connecting the wires together to have the circuit always closed and see if that solves it.

Never saw it personally but plenty of vids on youtube of what happens when you don't put it back up and drive off.