Bike dies when given a little throttle...

[KSAL]

So I've read though the carb guide a few times now and just don't really know what im looking for or where to start.

81 xs650
Stock exhaust cut open in the back removed baffles following how to on the site
Pamco
PMA
Batteryless w/ 40v 47,000uf cap http://search.digikey.com/us/en/products/B41456B7479M/495-4223-ND/2269432

So what is just confusing the heck out of me was last year I purchased the bike, put in the PMA and Pamco freed the exhaust and rode 500-1000 miles just fine no issues what so ever!

Let the bike sit over the winter and did some modding but nothing at all to the motor or carbs or exhaust! All frame, suspension, fork, and rewire and battery less. Anywho i got the bike running and made a short 5-10 mile trip with my friend and thought everything was great. I went to ride the next day and made it about 7 miles and it quit on me as i was coming down an off ramp off the highway.

I pulled in a parking lot and let it sit for a min and it fired up but when i went to twist the throttle a little it seemed to flood out and die. Brought it home by truck.

Took off the carbs today and cleaned them put in some new gas and it fired right up! GREAT.... wrong. as i let the bike warm up the idle got a little lower and again, i went to give it some throttle and it fell on its face, flooded out (or so i think) and shut off.

any ideas?? Thanks guys

 

[KSAL]

Can someone move this the the carb section. I don't know how i managed to post it here
Thanks

 

[retiredgentleman]

Does your fuel tank have rust inside? Do you have fuel filters?

You say you cleaned the carbs, but did you remove the pilot jet and confirm it is clear?

Rust/dirt may have got carried down into the carbs, and the pilot jet is the first thing to plug up.

 

[XSLeo]

You might want to test your charging ststem. If low output it can cause those syptoms.
Too high an output can hurt the Pamco.
I might suggest hooking a battery to just the igniton with the charging system unhooked from the ignition. If it runs ok on the battery the charging system is the problem.
With the bike running with the battery running the ignition you can test the output of your charging system.
Leo

 

[KSAL]

Well i think i figured it out.

I tested the charging system*an it is putting out 14.3-14.7 volts. so that was A Ok.

The petcock on the other hand seemed to not work in the ON position at all but turning it to the PRI setting worked just fine. Went out and rode probably 50 miles and it worked just fine. It did seem to idle kind of high but was great first ride of the year a little chilly though at 50-55 degrees.

 

[5twins]

Your bike is equipped with a vacuum powered petcock. In order to flow fuel in the "On" and ""Res" positions, you must have a vacuum hose connected to it. Usually, that runs off of a barb on one of your manifolds. With out vacuum power, the petcock will only flow in the "Pri" position. That bypasses the vacuum part and just flows straight through like a normal petcock. Check to see if your vacuum line is hooked up. Maybe it fell off one end or the other. If it is hooked up, maybe the diaphragm in the petcock went bad.

 

[KSAL]

Yeah the diaphram is broken, I had the vacuum line hooked up and was still getting nothing. Just decided to bypass that and run it on the Pri setting.

 

[5twins]

Be aware that the "Pri" position runs through the reserve pipe. You have no reserve now. When you run out of gas, you'll be really out with nothing to fall back on.

 

[KSAL]

Thanks for the heads up 5twins. I'll keep a close eye on it from now on until i get a new petcock