Manual conversion for early GT-series petcock

[jabcb]

Stock early GT550 petcock with 3 outlets shown in the reserve position. (Minus the filter bowl.)

Typically the inlet filters have fallen off on old petcocks that I’ve removed.
This is bad because these filters are before the vacuum mechanism. The filter bowl is after the vacuum mechanism.
Without these filters, crud in you gas tank can get into the vacuum mechanism & cause problems.

So I’ve been using JB Weld to glue the filters in place. Just don’t apply too much because it needs to fit in the tank opening.

GT550-PetcockMod_1923 by jabcb, on Flickr

[jabcb]

Pic of the modified petcock with purpose shown.

The passages are approximately the size of an M6 screw.

Based on what’s available at the local hardware store, I used a 1/4” set screw & tap.
This set screw needs to be recessed a bit, so make sure that it fits prior to mixing the JB Weld. The set screw is a bit loose without the JB Weld.
I put a good bit of JB Weld in the hole & on the set screw threads. (A little extra won’t hurt & you only get one chance to get it right.)

Make sure the set screw is recessed & meticulously clean up any JB Weld.

GT550-PetcockMod_1919 by jabcb, on Flickr


Pic of the modified filter bowl.

These passages are also approximately the size of an M6 screw.

Same procedure as the other set screw.
But you won’t be able to run the tap in very far. Use a really short set screw. It’s ok if it sticks out a bit.

GT550-PetcockMod_1920 by jabcb, on Flickr

[jabcb]

Modified petcock in the ON position.

Just flip the retaining plate over & install as shown.
You might want to apply a smidgen of grease to the spring & mating surfaces if the petcock operates too stiffly.

GT550-PetcockMod_1924 by jabcb, on Flickr

[jabcb]

The three positions for the modified petcock.
I’m going to apply a dab of red Testors model paint to mark the off position & a dab of green for ON. It's easy to forget that it's a manual petcock & what the postions are.

GT550-PetcockMod_1924 a by jabcb, on Flickr

[jabcb]

Surprisingly easy & cheap mod. Another forum member mentioned this is a post some time ago. He did this to several of his bikes with good results.