Got a vf500f and need help with petcock/carb rebuild.

Hello Everyone. First post here and in some insight on this bike. I just acquired a 1985 VF500F that has been sitting in a garage since 2010. I took the gas tank off and decided to drain the gas through the petock. If I turn the tank feed to on or reserve no fuel comes out (including off). I took the petcock out did a general external cleaning but no luck. Is this normal with no vacuum connected or should I assume its bad?

 

The fuel petcock is vacuum operated i.e. it needs a vacuum to open the fuel flow. After that the manual tap allows you to select off, main or reserve. So yes, you need to apply a small vacuum to the petcock in order for flow to occur. A vacuum brake bleeder is great for this.

 

I'd advise doing a compression test on that bike before investing any more time or money into repairs. How many miles on the thing ?

I'd need to hear a VF500 run sweetly before buying; did you ?

 

Thanks for the advice!

Appreciate the advice, the bike was free from my boss. He just came over and dropped it off a few days back. He was actually on his way to salvage yard to toss the thing!@!@#!@! Luckily he decided to see if I wanted it instead. I did a compression test right away and all cylinders are around 170-180. I rebuilt a 91 GSXR 750 a few years ago so have a good idea to what to look for on a non running bike. Not saying I am an expert but I have a general idea. I followed some instructions and did a carb clean up and found that the carbs were rebuilt not to long ago. I cleaned them out and re-assembled them and mounted them back up. The gas tank had a fair amount of rust so today i just finished de-rusting the tank. So far Ive invested 35 for the honda oil and filter and just found the battery it came with was completely shot, after 2 days of trickle charging only showing 8v and when i start the ignition only 0.2v haha so thats another 50. Hopefully she starts for me in a bit when its done.

 

O and the bike has 24k on it, hopefully the valves were adjusted if not just something else to work on . I do need some more tips though. I found that the fuel pump has been disconnected and the tank just gravity feeds to the carb assembly. The diaphragm for the petcock has 2 vacuum connections but there is only 1 vacuum feed that was originally connected and I am not sure when connection it goes too. Probably should have took a picture when i disassembled

 

I am assuming which ever vacuum assembly is actually connected is controlling the valve opening in the petcock, just cant figure out which one it is.

 

The vacuum port is the one at the outer end of the vacuum diaphragm chamber. The smaller plain fitting that points out the back of the tap opposite the tap shaft is a vent only, not connected to anything.

 

Thanks man!

 

-With compression numbers like that, you might have a WINNER ! Good luck.eaceful:

Be sure to test charging system output when you get it running, and change the fluids.

BTW: a trickle charger is good for keeping a well-charged battery up to it's max during rest periods but for actually charging a low battery, you need a 1-2 amp proper charger.