Getting random bursts of gas than none

Hi, I've searched the archives and couldn't find an answer. Bike idles fine, while riding it will bog and then shoot forward really quick, be okay for a little while, then do it again, very random. It seems like it's starving for gas sometimes and then gets a big shot of gas. I took the carbs off four times, cleaned w/carb cleaner and blew compressed air through all the holes. Could something else be causing this problem besides the carbs?

Thanks,
- Dawn

fuel tank vent plugged maybe??

Fuel starvation may also result from clogged petcock often due to crud inside the tank. Look for clogged screen on the petcock pick-up tube inside the fuel tank. May remove tank and flush it out to remove loose grit, etc.

Would also assure the in-line fuel filter isn't clogged. Fuel should flow freely through the filter.

If fitted with a manual petcock, would unscrew the sediment bowl, and assure the removable round filter screen is clean and unclogged.

But the reported issue might not be resulting from fuel starvation, and might be due to a sticking advancer unit.

If not already done, might want to first use a strobe type timing light to verify proper function of the automatic advancer unit to assure it's not sticking. With engine running, should be able to watch the advancer move quickly back and forth as rpm's are varied by blipping the throttle.

Good Luck!

To check for a possible fuel cap venting problem as suggested by fixer 5000, could try a test run with the fuel cap ajar (slightly open and not snapped down).

This test assures adequate tank venting during the test.

If the problem persists while running with the tank cap ajar, it's probably due to something else besides a clogged tank cap vent.

Good Luck!

Good ideas are up on the board already. If I were you I would try them in the order of easiness. First run it with the tank open. Next take off the petcock and give it a thorough cleaning along with the tank. If niether of those work, set the petcock to prime and see if there is an improvement. If there is it means there is something wrong the vacuum lines going to the petcock or the petcock vacuum diaphragm. That is if you have a vacuum petcock. If none of these work I have more suggestions but before we go there what RPM is this happening at and at what throttle opening. does it only happen when you snap the throttle open or when you roll it on smoothly. I'm assuming this bike has CV carbs??

Might have an intermittent wiring problem such as a loose connector or internally frayed wire that's causing loss of continuous voltage supply to ignition coils.

For example, a short in the kill switch, or in the fuse connection where battery voltage is being sent to the ignition switch, or a short in the ignition switch itself.

Can test run with temporary wire from battery positive terminal direct to red/yellow wire feeding coil primary terminals, which by-passes the stock wiring, fuses and switches. But don't leave this hooked up while the engine's not running because that's like leaving the ignition switch in ON position.

Good Luck!

I know this sounds obvious, but make sure the fuel line has no tight bends or kinks. Ed

I checked the petcock, no clogs, i got another petcock off another bike, i'm going to switch them. Tried the tank open, no different. FirstI will check the wiring I did just replace a coil a few weeks back with a used one. I didn't realize that it could be a coil/wire problem.

Thanks for all your help.