04-07 Frame Petcock - Different to Earlier models

[galahs]

We all knew that the 2004 - 2007 Frame mounted petcock looked different to the earlier GS500's well I pulled mine from my 2005 today to have a look inside and the differences are major!

I'll put up some photos later tonight but I can tell you this from looking at it so far.


- The Prime setting does NOT have a smaller diameter passage like the older models.
- The internal fuel hose diameter for the inlet and outlets is exactly 10mm or 3/8" (The older model was 7mm)
- You cannot easily mod the petcock to make it a manually operated version in the same way as the old one. But it can be done.
- The whole method of how it operates is different from the earlier models

[galahs]

Wow. I have discovered an extremely simple way of making it a manual on and off switch, as well as retaining its vacuum operation status.

Virtually a 2nd PRIME setting that uses the ON fuel line not the reserve.

I'm so excited! 

[galahs]

Ok here is a picture of the petcock disassembled.

It was very easy to do. Just five screws hold on the vacuum diaphram, and two hold on the front cover plate which holds in the fuel selector. The Fuel selector is just an interference fit and pulls out with a little force.





Now how to make the petcock have a manual ON selection that does not require you to use the PRIME setting which is fed from your reserve fuel line feed.

Just simply grind off the little tab on the fuel selector cover plate. The benefit of doing this is you can now have the improved flow benefits of the Prime selector with the convenience of retaining a reserve.




The following images show which chambers are fed in each position of the fuel selector lever.




ON (Vacuum operated or closed without vacuum by a spring so can be used as a manual off position)






PRIME (Gravity fed on position that draws fuel from the Reserve Line feed from the petrol tank)






RESERVE (Vacuum operated or closed without vacuum by a spring so can be used as a manual off position)






NEW PRIME (Gravity fed on position that draws fuel from the Main Line feed from the petrol tank)





So with this mod you can operate the 2004 - 2007 GS500 with or without vacuum and have the function of the bikes fuel reserve. I really would recommend this modification to all owners who worry about the vacuum system may fail and/or to prevent high speed fuel starvation issues.

Benefits:
- Minor mod, no major change to the petcock
- Normal petcock function is retained
- Vacuum operation is now optional
- Allows manual operation of the petcock (PRIME MAIN / PRIME RESERVE / OFF )
- Maintain functional use of the Reserve system
- Can use the stock fuel hoses
- Only requires a screwdriver and a file or dremel
- Nothing to buy!

Negative:
- Make sure you turn the dial to the exact horizontal or vertical postion as required. No tab to help with alignment

Note:
If you decide to only operate in manual mode only, ensure you block the vacuum line from the carburettor and optionally the vacuum input on the petcock (to stop dust/dirt/crap getting into it)

[ben2go]

HAHA you're talking to yourself. 


REVISEDSince I posted this,pics have been added.Cool trick.Anyone know if the newer petcock will fit the 89-00 models?

MODS CAN WE MAKE THIS A STICKY OR ADD IT TO THE WIKI?THANKS.

[Chuck]

I didn't reply because I had nothing to add, except man, that's f'n awesome.  Some brilliant engineer cooked up the 4-way petcock, and they made him put in that stopper tab so it doesn't confuse people.

[galahs]

It's a great design!

The double ended sword however is the diaphragm needle valve.

Good that even if the diaphram tears, the spring ensures the needle valve is seated. IE. No flow on the ON and RESERVE position. Allowing for you to continue using the petcock as a manual version.

Bad that if using the ON or RESERVE setting whilst riding in high speed traffic and it tears, your fuel flow will instantly shut off. 

[dgyver]

Something that was actually improved on since the GS was introduced!

[galahs]

So I went and purchased some 8mm or 5/16" fuel line.

Guess what!

It fits the tank petcock perfectly, bot doesn't fit the frame petcock!!!

The frame petcock input lines are definitely a 10mm or 3/8" connection!


Two 10mm lines only just fit next to each other on the tank petcock as the two exits are so tight together.
They are a touch looser than I'd like but they should be fine if you clamp them on down hard!!!!

Far out! 

[kml.krk]

well.... there is something nice in 04s+   

[jgreth]

Question, if someone were to leave the fuel selector in the NEW PRIME mode and shut off the bike and forgot to switch it back to 'ON', wouldn't it just flow constantly and flood the carbs?

[Chuck]

Yes, if the carb float needles are not seating properly.

[galahs]

Yes IF

but the advantage of using the new prime is, if you forget turn the petcock to run (effectively off) when you stop, and the carbs do drain, you wont loose your entire tank of fuel leaving you with a reserve to at least ride home/to get fuel.

[Anakist]

Does anyone know how to make this fit to the pre 04 bikes? I am starting to get starvation on the highway and am looking at swapping to a new petcock to keep the vacuum operation.

James

[jeremy_nash]

way to revive an old thread.............anyway, I have an 06 petcock on my 89.  the newer petcock is too deep to fit with the airbox.  I took a piece of aluminum and made a bracket to drop it a little lower and further out

[Chuck]

A lot of us have dropped the airbox for a rejet, though.  So you could kill a few birds there.  Rejet, put a lunchbox filter, and a newer petckock.

[Unknown]

Hmmmmmmmmmm, interesting

[beRto]

 

Sorry. I was quoting for a related thread (http://gstwins.com/gsboard/index.php?topic=45687.0) and I mistakenly revived this one.

It's a great thread, by the way... I wouldn't mind seeing it as a sticky!

[gsJack]

galahs, the center brass shaded connection in this picture is for the main line feed (petcock ON position) as you indicate.  Can you tell me which tube it connects to on the tank shutoff valve on your bike?  Is the long tube on the tank shutoff for the ON position or for the RES position?  My 3 diagrams (89-00, 01-02, 04-06) and 2 of the 3 setups in the parts fiches indicate the long tube is for ON but as pointed out to me by beRto in a recent PM the pics and diagram posted Kerry show the opposite. 



Is this diagram which is same pic as shown in parts fiches correct for your 05 F model:

http://img.photobucket.com/albums/v443/jcp8832/04-06fuelcock.jpg

The parts fiches are incorrect for the 01-02 models which I have an 02 handy to confirm.  May have to go over to son JP's house to check out my old 97 for the 89-00 diagram,  my memory is slipping on that one.

I can see where there have been a number of revisions to the diagrams in the parts fiches since I made my diagrams and I'm posting revised diagrams under the same urls in my photobucket.  Will revise further if I have them backwards but that's just labeling and doesn't affect the pics.

All of the tank shutoff valve/filter parts numbers are the same for all years 89 to present

[galahs]

The long shaft on the tank shutoff is the reserve.

The brass petcock tube is connected to the short tube (main) on the tank shutoff 

Like you've mentioned in other threads about older models, the way to prevent mixing up which hose goes where on the 04 + GS's is that they do no cross over each other at any place.

[gsJack]

Thanks galahs, that completes the whole picture now I hope.  If anyone sees anything wrong let me know and I'll fix it up.  Seems our 01-02 models are the only ones where the fuel lines cross:

http://img.photobucket.com/albums/v443/jcp8832/GS500fuelcocks.jpg