I read a post ( Fuel Off Valve ) by SRchop16 concerning the stock fuel valves on the Z400. In that post, NormalZ gave a link ( Bypass the vacuum fuel valve ) to another helpful post. I have a 2006 Z400 and a couple people towards the end of the post advised that this procedure doesn't work on 2006 models. I have had problems with my 2006 stock petcock and I wanted to thank all of you that helped out. I decided to take my petcock off to clean it and look for a way to make the mod work on 2006 models. I was able to come up with a solution to the problem. The mod is as follows.....

1- Remove the entire petcock from the gas tank.

2- Remove the "vacuum line cover" from the back of the petcock. Be careful, there's a spring inside


3- Pull out the "vacuum line plug" being careful not to damage the square rubber gasket (disregard the yellow circle in the picture)


4- Cut around the "vacuum line plug" to remove the square rubber gasket. You should have something that looks like this.


5- Keep the square rubber gasket and set aside the "vacuum line plug" and the "vacuum line spring", these won't be reinstalled.


6- Plug the small hole on the inside of the "vacuum line cover" and the exterior "vacuum line tube" to stop gas from leaking in to the vent line. Before I pluged the inside small hole......


After the plug.....


I used this stuff from Advance Auto Parts called "Quick Steel" ($4.68). It's an epoxy that sets up in 1 hour and is impervious to chemicals.


7- After the plugs that you made are dry, reassemble the "vacuum line cover" with the square rubber gasket. Don't reinstall the spring or the "vacuum line plug" that was cut off of the square rubber gasket.


8- Vacuum is no longer needed on any position on the fuel valve. The "on", "reserve" and "prime" positions are all free flowing now. Keep in mind that running with the fuel switch in the "prime" position is just like running in the "reserve" position.

9- After completing this mod, you will no longer have an "off" position. To solve this, I purchased an in-line fuel shut off valve from Tractor Supply ($6.94). It's made by Briggs and Stratton (part# 5091). To shut off all fuel flow to the carb, I simply turn this in-line valve to off.



valve open....


valve closed...


I also hooked the rubber vacuum line back up to the back of the petcock and carb just to keep junk out of the carb. I also installed an in-line fuel filter and Tusk gas cap while I was at it.


Please excuse my dirty ride. I had to test this mod out. I have no leaks and no more vacuum problems. My ride runs good again.... and now I have "on", "reserve" and a real "off" position.

Great write up but for all your work and the money it cost you you could of got a new petcock for 20 bucks.I read that a raptor-660 works.I used an old petcock off an old oversized kawi tank that I have.

It takes about a half hour to do the mod (not including the dry time) and costs $12. Went to McDonald's with all the money I saved.

Pinned... Good write-up, explanations, and pics. Good job!

Other than the loss of reserve, what other advantage is there to just running on prime?

z

Some find that the fuel flow in the "ON" position is inadequate or inconsistent. Running it on "Prime" is the same as "on" on a standard petcock.

You have to run on prime if you get the FCR carb. Most popular carb option.

I havent tried it (yet) but I have heard that a 660 raptor fuel petcock will fit it.

i have a stock carb and i noticed my bike runs like sht on the ON part, doesnt get enough fuel...i just turn it on PRI and it hasnt failed yet....



in the manuel it says to never leave the bike on the PRI position when not running, i've forgot to put it back in the ON position a couple times and left it for about a week and nothing has happened, bike started up fine...



is leaving it on PRI actually that harmful to my quad?

If the needle valve is good in your carburetor, then you will never have a problem with the pri position.
Pri is reserve that does not shut off when the engine does. It is manual reserve.

so what is the real benefit to this mod?? just curious. thanks
dave

running in the prime is just like running in reserve so when your out there is nothing left but if you mod it you can run an fcr carb in the on position and still have the reserve so you dont have to walk back to the truck to get your gas can. and trust me i've had to do it and it sucks.

Search, there are several folks on here who use raptor petcocks.

I had a problem with the raptor petcock. The selector was rightup against the frame so I couldn't turn it. I just did a mod similiar to this and plugged off the vacuum hole. I run the FCR thats why I had to do this.

MYZ, what kind of problems were you having with your 06 and the petcock?? I have a 06, and it doesn't seem to want to start. I'm interested in knowing what your problems were......

Thanks!

My quad would die shortly after starting. Then wouldn't want to start again for a couple minutes. Turned out that the petcock wasn't letting gas go to the carb because of a vacuum issue. From what I've read on this forum, if your quad is hard to start from the get go, you may have bad valves.

Interesting! Mine wont start now, after a washing. I'm thinking starter jet, or even pilot jet....... My Z would start right up everytime. I'm ready to pull my hair out over this!!!

I have had the raptor 660 petcock on my wife's z400 for months, and it has worked perfectly, no issues whatsoever.

same here

A Blaster fuel petcock will directly bolt up. Not sure of the flow rate or any of that stuff , but thats what I run on mine with that FCR.

So will a Raptor Petcock.

I just tapped my stock vaccum side to 3/8" and ran a plug into it. Run on Prime.

This mod, and the thread, were made for the 2006 and up models. What you state (with your 2003) won't work for the 2006 and up - and that's why the OP went through the trouble to research, find a solution, and write up this article.

That's listed in the title of the thread, and in the opening paragraph, so I don't know how you missed that. Thanks for playing, though.

tom i think he means he didn't do the mod in this thread, just plugged the vacuum port and runs it on prime now. atleast its what it sounds like

That works, prior to the 2006 model. That's the whole point of this thread in the first place.

Here's the part numbers of them all - order the parts, take them apart, and check out the differences.

SKU: 44300-07G00
PETCOCK ASSY, FUEL MODEL K3

SKU: 44300-07G01
PETCOCK ASSY, FUEL MODEL K4/K5

SKU: 44300-07G10
PETCOCK ASSY, FUEL MODEL K6/K7

This thread was made specifically for the 2006 and up petcocks, nothing else. '03~'05 mods to the petcock won't work on the '06 and up. Because he was the first guy to invest the time, figure it all out, and make a damn good writeup - it got pinned. If specifically states 2006 in the title, too.

In answer to the question as to... why block off the vacuum line? A ruptured or non existent diaphragm allows a direct passage of raw gas back to the vacuum source. This would cause a rich fuel air mix if the vacuum source leads back to the carburetor or the air intake

Also, not being able to positively shut off the petcock with a secondary valve will cause gas to fill up the crankcase and oil resevoir if the float needle valve is faulty or should stick open. If that happens you have to drain all the contaminated oil and gas from the engine.

in step #3 of the OP's first post shows the yellow circle around the diaphram o-ring. If you just take off that o-ring on the end of the "plunger" it will flow fuel freely and you dont have to plug any ports or use fake metal. Thats all I did to my petcock when I installed my FCR a couple weeks ago, then I installed a shutoff valve just like the OP did. Good write up though!

I just use prime..
I also bored the fuel passages out to 1/4" for more flow.