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Ok, I know right off there is a few of you unsavory types that were immediately intrigued by the thread topic......

This a pet peeve I have. Always employ the KISS concept (Keep It Simple Stupid). In this case it's the Suzuki engineers for creating a vacuum actuated fuel petcock. Not only is this device unnecessary and doomed to fail, as found on every Suzukish machine I've owned, it's down right annoying. Every time you remove the fuel line you have to clamp off the line with a hemostat.
It can also ruin your day as I have seen several times. Today was my day.
I pull the up-to-now trusty KLX400 out for a leisurely ride to work. I notice a slight fuel drip, uh oh. I have a sinking feeling I know what's wrong. I go ahead and hit the starter. Kerchunk at TDC....liquid lock. I drain the oil after work, good news no gas in the oil. Pull the spark plug and hit the starter. At this point my advice is to stand upwind (which I wasn't). Oh the joy of getting soaked with a shower of gas.

Here's what happens: With the fuel always on, the float needle can leak flooding the bowl. The fuel slowly migrates through the jets into the intake. When I cranked the engine it got a full gulp of solid fuel and couldn't get past TDC. Hopefully this is all that happened. I have witnessed the vacuum petcock fail on a brand new bike and fill the crankcase completely full of gas.

I'll be ordering a replacement manual petcock this weekend.

Right now I could use a Suzuki engineer. I can think of a prime location to stick his petcock.

Buy a Husky and don't light a match!

So, me bad, but I almost never remember to shut off the petcock when I put the bike away after a ride. Heck, my LC4 has sat for months with the petcock open and no fuel gets past the Mikuni. My float needle keeps gas out of the engine. So that is one problem. Could your float level be set too high? Might there be some dirt between the float needle and seat?

Although a vacuum petcock seems like a nice safety feature, that is only true if it works consistently and doesn't fail. Obviously this doesn't fulfill the latter requirement.

Yes usually the float valve should be the fail safe. I did a bunch of internet reading last night. Seems to happen even on brand new bikes, you never know when the float valve might not do the job. On the three Suzukis I owned, all of them had faulty vacuum petcocks, I had no problems until now. I figure it's not worth the risk, plus the annoyance of clamping off the fuel line whenever you remove the tank. The DRZ400e off-road model does not have a vacuum actuated petcock.

I called a Suzuki dealer to see what a replacement DRZ400e petcock would cost - $85, more then I was willing to pay. Internet threads suggested going to a Yamaha dealer and picking up a petcock for one of their off-road models.
Problem solved. Yamaha dealer found a exact match sans the vacuum part from a Yamaha ATV - a whooping $21.

Before I took the bike apart, I opened the float drain and ran some fuel. Afterwards there was no leak, so most likely I had a piece of garbage in the float chamber from winter storage. Glad it didn't happen a couple weeks ago in Arkansas.

Here's a tip that you won't need anymore with your new and improved petcock: I know mine and Mike J.s old DRZ are the same way...If you turn the petcock off and remove fuel line it gushes out like Niagara Falls. I simply leave the petcock in the ON position and yank the fuel line off. It doesn't leak a drop on me and I have done this many times.

KC wrote:Here's a tip that you won't need anymore with your new and improved petcock: I know mine and Mike J.s old DRZ are the same way...If you turn the petcock off and remove fuel line it gushes out like Niagara Falls. I simply leave the petcock in the ON position and yank the fuel line off. It doesn't leak a drop on me and I have done this many times.

Now that is just bass-ackwards! But good to know if you own a DRZ.

Stupid DRZ's!