fuel petcock doesnt want to work

[Anonymous]

when i try and run my bike with the petcock in the ON position it bogs and i get no power. it runs fine when its in prime. but prime shoots gas out and then i have no reserve and ive allready ran out of gas twice.

[terry]

Sounds to me like you've got a vacuum leak mate, check the little hose from your carb (#2 I think from memory) to your fuel tap (petcock) and see if 1, it's connected at both ends and 2, if it's cracked and sucking air.

The prime position doesn't require vacuum to open the diaphram and allow the fuel to flow, so that's why it's probably running Ok in that position.

It could be that there is a blockage in your petcock, or maybe the fuel cap vent, but I'd try that little hose first before I pulled anything else apart. :twisted:

[KEITH KRAUSE]

Good advice Terry. Check/replace the vacuum line, also clean the gas cap vent as normal maintenance. To test the petcock diaphragm for proper operation, just suck on the vacuum line (carefully). If you get any fuel or you can't create a suction, the diapragm is failing.

[Anonymous]

petcock probs

I just finished a ignition problem only to find out my petcock is not working. I took the spring out to create flow and the bike still will not turn over. Is the lack of the spring creating a flooding problem? Do I need to re tweak the jet for such flow? Man I am confused??>>< :roll:

[Jethro]

I just finished a ignition problem only to find out my petcock is not working. I took the spring out to create flow and the bike still will not turn over. Is the lack of the spring creating a flooding problem? Do I need to re tweak the jet for such flow? Man I am confused??>><

Lack of a spring shouldn't cause flooding as the fuel level is governed by the floats. Besides, even with flooding you would probably get some kind of sputter. Do you get any spark at all?

[Anonymous]

Plugs are firing

I check to see that the plugs are firing and they are. I suck ( oh so carefully) on the vacuum part of the petcock and gas started to flow where it was supposed to. I hooked everything back up and she still won't turn over. I think there is not enough vacuum. If I made the hose shorter would this create a stronger vacuum? 8O

[Anonymous]

No, shortening the hose won't change the vacuum. Do you have fuel in the carbs? If not, you need to go to prime for about 15 seconds to fill the carbs.

[Anonymous]

Running!!!

After the ignition prob I placed the throttle control in the wrong slot. After placing it in the right position...Walaa.... Bike runs But battery does not recharge. Voltage regulator ???what do ya Think??? :twisted:

[terry]

Re: Running!!!

After the ignition prob I placed the throttle control in the wrong slot. After placing it in the right position...Walaa.... Bike runs But battery does not recharge. Voltage regulator ???what do ya Think??? :twisted:

I think you should leave your bike maintenance to someone who knows what they're doing Bill, "owning a ferrari doesn't make you a ferrari driver, and owning a tool kit doesn't make you a mechanic,either". :twisted:

[Anonymous]

Petcock

Culd some one give me some information on the 3 positions on the petcock (79 GS550L) and how the handle is positioned for proper usage.
Thanks

[QuaiChangKane]

"On" is for normal use, "Res" is for reserve, and "Pri" is for prime.

The reserve setting is for the bottom 1/2 gallon or so of fuel - it's pretty standard on alot of bikes, and comes from the fact that most bikes don't have fuel guages. So, if the bike stalls in the "On" position, you switch it to reserve and still have (hopefully!) enough gas to get you to the closest station (your trip meter helps to judge fuel consumption, too).

Since your bike's fuel petcock is vacuum-fed, the "On" and "Res" settings will not allow fuel to flow to the carbs unless the engine is running and creating a vacuum to pull fuel from the tank. The "Pri" setting is used if the bike's been sitting for awhile - some say more than a few days, some say two weeks or more - if the float bowls on your carbs have dried and the bike will crank but not start. This setting opens an additional air valve on your fuel petcock which allows fuel to freely flow into the carbs. Use this setting for 15-20 seconds, then put the switch back to "On" (or "Res" if it's low on gas), and crank the bike. Just be sure not to leave it on the "Pri" setting, or you will flood your carbs - this can lead to them overflowing, fuel contaminating your oil, and a whole slew of possible nastiness.

The nice thing about a vacuum petcock is that you can disconnect the fuel line from a full tank if the petcock is set to "On" or "Res", and remove the tank for maintenance (like valve adjustments and carb balancing) without spilling any gas. The petcock is a part that needs periodic maintenance, though - and some special care for yours since the tank was dirty. There's a screen inside that can get clogged, and a diaphragm that can leak. Just search the forums for "petcock" - there's alot of good stuff in here.

Be advised that replacement petcocks run $80 or more if yours goes south, and rebuild kits are getting harder to come by!

-Q!