Bike will not stay running.

cookena69er2

cookena69er2

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I really hope you all can help me out here, this is my first motorcycle i have ever owned and i'm a newbie when comes to working on it. I have rebuilt cars from the frame up, so i'm handy with a wrench just inexprienced.
I own a 1980 XS400G. It has 11,000 miles on it. No motor work done to it that i know of.
It was running great for the last 2 months. Then last week i decided to put premium gas thru the ol bike. I got about 4 blocks away from the gas station, and it died at a stop light. It did not want to start again. After about 30sec of cranking on it, it finally started. When i took of it was spittin and sputterin, and wanted to die. Once i got it up to speed (4000-5000rpms) it ran perfect. I Tried to take it to work the next day and it ran alright in the morning, it was a little rough running in a few spots but it did alright. When i left work it was whole different story. I had to keep the rpms up around 3000 when i was at a stop to keep it running, and when i would try to take off i had to keep the rpms above 4000 to keep it running. If someone can help please. I miss riding. :(
 
From what you describe I'd say you got a load of bad/dirty gas. Do you have an inline gas filter? If so you could try changing it for a new one. Otherwise I'd suggest a good carb teardown and cleaning with the installation of an inline filter afterwards.

Another possibility is a coincidental (with the fillup) failure of the petcock. Try turning the petcock to PRI and see if the bike runs normal.
 
I do have an inline filter, i will try and replace that and see if that doesnt help. I tried running the bike with it on PRI and RES, there wasn't any differnce.
 
make sure the vacuum tubing from the gas tank is hooked to the carb but it does sound like something is going on with your carbs
 
I replaced the fuel filter lastnight and it seems to be running a little better. But not perfect. I also checked the vacuum line and it was good. So i guess i'm going to tear down the carbs and clean them. I have been wanting to put air pods on my bike so i guess this would also be a good time to put a jet kit in my carbs as well.

Does anybody know were to get a good jet kit for my bike?
 
My personal advice would be to get the bike running well before changing things like the air filters. If you switch them now while working on your carbs you won't have a baseline to work from when you do add pods. Once you get it running right stock, change one thing at a time to see what differences it made, FWIW.
 
Very good advice from chkm8. You ccould try simply pulling apart the carbs and very thorough cleaning first. There are a few threads on the necesary details but do not boil/soak your carbs in any cleaner for any real lenght of time unless you have already removed EVERY rubber/plastic piece or plan to replace it.
 
Wear goggles. Save gaskets and carefully reuse them. It's easy.

You can take the carbs out very easily on that bike. Remove air boxes first, then rear boots, then loosen carb boots and pop the carb loose. Detach cable to accelerator, and slip the carbs out from the frame.

Clean off the outside of the carbs FIRST. Degrease them with some liquid degreaser in a spray bottle. get the freeplay, springs and arms loose of grit and dirt. You don't need acetone or spray carb cleaner to do this job right. Just degreaser to start.

When the outside of the carbs are spotless, and I mean really spotless, get a cardboard box or pizza box and punch it with holes in rows and squares. Stuff the screws you remove in the same shape as they come off the carbs and keep left side left and right side right.

Remove the bowls first (they have a drain plug on the bottom) and soak them in pinesol for a day. take off gaskets before soaking. Any resin inside won't stand up to pinesol. I removed my resin with a boil in barkeepers friend. The resin is caused by ethanol additives gathering water in the float bowls. After they're soaked, to into them with the tiny flat head and unscrew the jets. Put them in a small glass jar of acetone or spray them with carb cleaner and blow them free with compressed air.

you are looking for clean air passages, with light shining through.

Those done, reassemble them and make sure the jets are in the right amount, with the correct number of rotations before putting them back on.

Now for the rest of the carbs. Carefully press out the emulsion tube (vertical and with rows of holes around ) from the inside upward. They pop up and out. The little holes need to be free and clear.

Clean out all the passages with spray. Wear goggles please.

Unscrew the tops of the needle and diaphragms. Carefully set aside the screws, the springs, and then slide the needle diaphragms up and out. Clean them off. Make sure they slide. No hole in the diaphragms.

Look at your floats, make sure they have no holes and no bubbles come off them in a glass of water. The crude way the floats regulate fuel flow into the bowls is how hard they press on the needle, so make sure that tab is the same elevation on both floats. It's crude, but it works.

Clean all passages of resin and gunk with a pinesol soak or a brush and solvent. Remove the sediment by hand if you have to. I needed a wooden chopstick and green 3m scrub pad to remove my resin/rust stains in my bowls.

You are dealing with vapor pressure inside a carb. Not liquid pressure, as in drops of clearly definable liquid, but with misty flows of gaseuos air. As in, it has to be clean of flakes/dust. Specs of crap will clog these passages, Tiny flakes of crap will clog these passages. Bikes don't burn gas, they burn the fumes coming OFF the gas, so it's really a thin misty flow through all these bits that's necessary. Keep that in mind for how clean it has to be. Small things can block flow.

After the passages are clear, the diaphragms are tested for holes, and everything is put back together, reassemble your now clean carbs. Reinstall. Don't be butt hurt if you have to go back in. There are many screws, passages, holes, floats and jets in a carb, and if you forget one bit, you'll need to redo it. It's part of the zen.

Ride safe

Drewcifer
 
Wear goggles. Save gaskets and carefully reuse them. It's easy.

You can take the carbs out very easily on that bike. Remove air boxes first, then rear boots, then loosen carb boots and pop the carb loose. Detach cable to accelerator, and slip the carbs out from the frame.

Clean off the outside of the carbs FIRST. Degrease them with some liquid degreaser in a spray bottle. get the freeplay, springs and arms loose of grit and dirt. You don't need acetone or spray carb cleaner to do this job right. Just degreaser to start.

When the outside of the carbs are spotless, and I mean really spotless, get a cardboard box or pizza box and punch it with holes in rows and squares. Stuff the screws you remove in the same shape as they come off the carbs and keep left side left and right side right.

Remove the bowls first (they have a drain plug on the bottom) and soak them in pinesol for a day. take off gaskets before soaking. Any resin inside won't stand up to pinesol. I removed my resin with a boil in barkeepers friend. The resin is caused by ethanol additives gathering water in the float bowls. After they're soaked, to into them with the tiny flat head and unscrew the jets. Put them in a small glass jar of acetone or spray them with carb cleaner and blow them free with compressed air.

you are looking for clean air passages, with light shining through.

Those done, reassemble them and make sure the jets are in the right amount, with the correct number of rotations before putting them back on.

Now for the rest of the carbs. Carefully press out the emulsion tube (vertical and with rows of holes around ) from the inside upward. They pop up and out. The little holes need to be free and clear.

Clean out all the passages with spray. Wear goggles please.

Unscrew the tops of the needle and diaphragms. Carefully set aside the screws, the springs, and then slide the needle diaphragms up and out. Clean them off. Make sure they slide. No hole in the diaphragms.

Look at your floats, make sure they have no holes and no bubbles come off them in a glass of water. The crude way the floats regulate fuel flow into the bowls is how hard they press on the needle, so make sure that tab is the same elevation on both floats. It's crude, but it works.

Clean all passages of resin and gunk with a pinesol soak or a brush and solvent. Remove the sediment by hand if you have to. I needed a wooden chopstick and green 3m scrub pad to remove my resin/rust stains in my bowls.

You are dealing with vapor pressure inside a carb. Not liquid pressure, as in drops of clearly definable liquid, but with misty flows of gaseuos air. As in, it has to be clean of flakes/dust. Specs of crap will clog these passages, Tiny flakes of crap will clog these passages. Bikes don't burn gas, they burn the fumes coming OFF the gas, so it's really a thin misty flow through all these bits that's necessary. Keep that in mind for how clean it has to be. Small things can block flow.

After the passages are clear, the diaphragms are tested for holes, and everything is put back together, reassemble your now clean carbs. Reinstall. Don't be butt hurt if you have to go back in. There are many screws, passages, holes, floats and jets in a carb, and if you forget one bit, you'll need to redo it. It's part of the zen.

Ride safe

Drewcifer
 
@Drewcifer you've got to take that set of instructions and put them somewhere where people will find them! I've read a lot about carb cleaning over the past few days and this was definitely the best write up I've seen. Thanks
 

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