Disable vacuum on petcock

[kurifu]

So for thos ewho sawmy last thread, looks like I have a fuel leak down the vacuum line on my petcock. I am not too eager to run out an purchase a new petcock yet, though I will do this soon, I am wondering if it is ok to completely remove the vacuum line in the mean time and plug the vacuum port on the 2nd carb (and on the petcock) and run the petcock in prime.

My float bowls are clean and the valves work well so I am not worried about overflow or leaks, and I should be able to use the "ON" position as the off position if I do this.

In theory this all seems like it would work well, and the fuel sender on the tank works so I am not worried about loosing the reserve feature of my petcock, of course when I have the petcock on prime, does anyone know if it is taking fuel from the reserv position or if it is coming from the on position in the tank.

I have a 1980 GS1000G if that helps.

Is it possible to get a petcock that doesn't require the vacuum and simply has an on/off/res position?

[fgh]

If its leaking out the vacuum I don't know if it'll matter what position its in. Yes its OK to plug the barbs for the vacuum line and run it. If the floats are working OK then you can leave it like that forever. It would probably allow fuel through in the "ON" position with the engine off. When its in "PRIME" it will be flowing fuel from the reserve portion of the tank. I don't know if you can find a standard petcock for your tank. LOL

[kurifu]

I can use silicon to plug the vacuum barb on the petcock, that is minor even if fuel is trying to leak when the fuel is in the on position and the engine off, what I meant is that there is not fuel coming from the fuel line when the tank is left in the on position, I know this is the case because my tank is disconnected right now and there is not leak, in fact not even from the vacuum port.

It is a very small amount if anything that comes out, and apparently only when the vacuum is applied.

[robertbarr]

Your approach should work fine, as long as there's adequate flow in the Prime position of course.

[gustovh]

If you are going to leave the valve on prime, you had better check the oil level each and every time you start it up. Gas in the oil is not a good thing.
V

[Dan Ruddock]

I have seen new diaphram kits on ebay for cheap to repair your old petcock. That is what I would do if mine leaked. Dan

[t3rmin]

Silicone won't work to seal the petcock vacuum port. Silicone is eaten by gas. Grab a rubber vacuum cap from the auto parts store.

[twistedwankel]

Get a new petcock.

I can use silicon to plug the vacuum barb on the petcock, that is minor even if fuel is trying to leak when the fuel is in the on position and the engine off, what I meant is that there is not fuel coming from the fuel line when the tank is left in the on position, I know this is the case because my tank is disconnected right now and there is not leak, in fact not even from the vacuum port.

It is a very small amount if anything that comes out, and apparently only when the vacuum is applied.

The repair kits they sell are only for the front side where the knob is. The rear side vacuum operated ON valve kit isn't available. The design is that the engine when running will open the ON valve and it closes automatically via a spring when engine quits.

Personnally I just gave up and bought a new valve after seeing what the kit consisted of which is useless. The first one worked for 23 years. Was about $50 from Bike Bandit and a factory part. In doing so I avoided a future problem with a rusty tank as the paint was gone under the original gasket and I fixed that at the same time. The screens that come on it are CLEAN and Straight too. I hate walking almost as much as I hate fires.

[Norseman]

+1 to above post by Twistedwankel. I just finished maintenance on my newly acquired Kawasaki KZ1000 where the PO had installed a fix-it kit on petcock. The bike sat for a couple of months, allegdly not on prime. It takes four quarts of oil, and I drained five and a half quarts of very thin liquid. Guess what that extra quart and a half was...

It's well worth the cost to replace the petcock with factory equipment. When it comes to fuel - no compromise or cheapness!

[t3rmin]

I swear I drained close to two gallons of oily gas from my new project yesterday (first oil change after fixing carbs). That explains all that blowby... sheesh.

[kurifu]

The intention is to replace the petcock, I just need to get by in the mean time.