Vacuum petcock to Manual conversion?

I know this is probably something that gets asked regularly. I just can't find something specific.

I have a 78 KZ650 B (I think) and the stock petcock has me worried. It's dumped in the crank case once already. I know they make rebuild kits, I just had a crazy Idea. Would it be possible to block the PR part of the valve and turn it into the off then remove the vacuum function?

So:
Reserve = reserve
PR = Off
On - On with out a vacuum

Has anybody tried this?

I'm not quite sure what you mean but it would be pretty easy to install a manual petcock and just plug the vacuum port on your carbs.

Based on what I've read around here, there can be some pretty strong feelings on either side of the manual vs. vacuum petcock debate but I switched to manual recently on my '81 650 CSR.

-Barry

I don't think it will work. The diaphragm plunger is what stops the flow of fuel, so you'd have to remove the diaphragm or the o-ring, but then there would be nothing to stop the fuel. The way PRI works is that it bypasses the diaphragm, engine running or stopped. With the petcock set to PRI with the engine running & assuming a full tank, there's still fuel flowing thru the main orifice in the petcock, but there's also fuel flowing thru the PRI orifice. Engine stopped, fuel only flows thru the PRI orifice as the diaphragm plunger blocks the main fuel orifice.

Installing a manual fuel valve is easy on the 81 650-CSR as it has a 34mm bolt hole spacing & there are plenty of options.
Earlier 650s are 44mm, so I think on those you might have to get a fuel valve & mounting plate. I've never seen a 44mm manual fuel valve.

No eBay APP ID and/or Cert ID defined in Kunena configuration

martin_csr wrote: Installing a manual fuel valve is easy on the 81 650-CSR as it has a 34mm bolt hole spacing & there are plenty of options.
Earlier 650s are 44mm, so I think on those you might have to get a fuel valve & mounting plate. I've never seen a 44mm manual fuel valve.

Exactly right, Martin. The OP would need something along these lines: