Petcock Problem ???

Ok after some much needed work I am unable to start to motorcycle.
Sounds like it is starving for gas.
My petcock will flow under no vacuum in the RES position only, It will flow when under vacuum in the ON and PRIM position.
I don't think this is correct but would like some guidence.
Thanks
Brian

 

Without the motor running, fuel should only flow in the PRI pos'.
Test it by, running one line from the outlet to a can & another line from the vac port of the petcock, suck on this one & you should get fuel in the can & none in your mouth, if this is the case the petcok is ok & maybe you have dirty filters.

 

Thats How I tested. And can flow with vacuum on PRIM and ON. What are these filters you speak of ?
When I applied vacuum I did not get any gas through the vacuum line.
I just recently installed a new inline filter for the gas line and was able to see there is no fuel getting to the carbs.
Thanks
Brian

 

have you got the in-line the right way round (easy mistake) there is a tower filter on top of the petcock in the tank..........

 

also, it's the lever of the petcock that should point to PRI or RES

 

Yes its flowing the right direction. I had to change it yesterday when I started looking.
Never new there is a filter on the top. I will drain the tank and remove petcock to check that.
It has been removed all winter while the bike has undergone some cleaning and painting.
Thanks
Brian

 

I'm working on a petcock rebuild article, you guys are getting ahead of me...

If the plastic gauze "filter" (standpipe?) in the tank dried out with fuel residue in it, it's very possible it's plugged up. Not the most robust invention...

 

OK guys....just pulled the petcock off and no filter.
Air will only flow through the reserve not the Prime or on position.
Im at a lost and not sure what to do.

 

I am such an A**. My petcock is fine....I think the new fuel filter has some issues. Reinstalled old gas lines and will measure gas in bowls to verify the floats are functioning properly.
Thanks
Brian

 

Brian, did you decide you were reading the valve wrong then? You should have free flow in PRI position and no flow in RES or ON unless the bike is running and creating a vacuum.