Petcock Questions

Anybody have pictures of their petcock disassembled, and if they could post them.
Took mine almost all the way apart but dont'want tomess it up. The plastic block is loose but won't come out, unless I force it, and I don't want to wreck it.
What is behind the block, another diaphram?

 

How about an exploded view of the petcock from a manual.
Could somebody post that?
Please

 

http://web.mac.com/richardemassey/iWeb/ ... 830A4.html

 

Here's the holy grail of petcock repair:

http://www.maxim-x.com/petcock.html

Great pictures, writing, and everything he says about the problems with the petcocks (and the solutions) is right on. Although this site deals with the 700/900 petcocks, all of the basic info is the same for the 550/650/750/1100 petcocks.

The only thing missing is that not only is there sometimes (rarely with the smaller 550/650/750 petcocks) an o-ring seat bore alignment problem, but also that the bore seat itself can get scarred and needs to be restored during the rebuild process. The golf-tee "polishing" method works, although it is somewhat cumbersome to do.......

The plastic block (spacer plate) that you refer to has a gasket on both sides, and the side that is towards the front of the petcock normally "glues" itself to the petcock body pretty strongly over time, and you have to carefully pull up a tiny edge of the gasket and start "peeling" it off. Easy to tear the edges of the gasket, but that won't matter, as long as the tear doesn't go into the cavity area.

Note when re-installing that the weep hole in that plastic plate faces the rear of the bike. Also note that there are molded-in alignment pegs in the plastic plate (both sides) that the aligns the gasket and the plate with both the petcock body, and with the vacuum cover plate.

None of the above will make sense until you have the petcock apart and in front of you. Otherwise, I fully realize it all sounds like gibberish!

 

Here’s a thread with pictures of the diaphragm..........
http://www.xjbikes.com/Forums/viewtopic ... tcock.html

Here’s a thread with pictures of the tank filter...........
http://www.xjbikes.com/Forums/viewtopic ... tcock.html

 

Thanks guys,
That's what I was looking for.

 

Looks like it would be less expensive, and troublesome to just get an adapter plate and new petcock that has the off position

 

Well, yes, only downside is that you have to drill the hole in youir tank a bit wider to accept the larger filter unit on the aftermarket fuel valve. And once you enlarge that hole, there's no real way to ever "go back" if you ever so inclined to do so. Minor issue but one to be aware of..........

 

You think these require the tank to be modified?
adapter
and
petcock

 

Yes.
You'd have to "Open-up" the oval to allow the outside diameter of that new petcock in to the tank.

There are more than a few who have done it. You just have to remember to turn it on and off ALL the time ... otherwise, you be changing oil and filters alot.

 

A brand new Yamaha OEM petcock is only $62 from zanottimotor.com. It will last another 20 years, save hours of adapting/messing about and will cut the fuel flow automatically when the engine is off.

Fuel pouring into the crankcase and possibly pooling underneath the bike is just not worth the trouble or fire risk.

Go for a new one.

 

Fuel Valve:

fp17) Aftermarket Complete ON-OFF-RES FUEL VALVE. Not really a "petcock" in the XJ sense of the word. Yamaha designed their petcocks to be a very clever "automatic" fuel supply valve, meaning it has to have engine vacuum for it to function. Great idea (when it works) because it allows us to basically "set it and forget it". Bad news is that when the seals go bad, or as age wears the internal components, it can become a really bad idea, since it will leak fuel into the carbs when it's not supposed to, leading to flooded carbs, fuel in the crankcase, spun bearings, etc.

This true fuel VALVE is either ON (in either the standard "ON" or the "RES"erve positions) or it's OFF. And it doesn't depend on engine vacuum, just gravity. So it won't ever leak or pass fuel in the OFF position. That's the good news. The bad news is that you have to remember to turn it on or off manually (as in every time you start your bike up or shut it down) or, instead of blaming a faulty petcock for your resultant problems, you'll have to blame yourself!

Once installed, this unit fits and looks somewhat the same as an original XJ-series petcock, what with the chrome faceplate and selector lever. It obviously has no vacuum nipple, only a rear-ward facing fuel outlet, which means you will need to remove your petcock vacuum line from the #3 intake manifold boot nipple and replace it with a rubber block-off cap plug. This fuel valve uses the same size fuel line as original.

You also must use a adapter plate on the bottom of your fuel tank that this fuel valve screws into, and the brass-mesh, in-tank fuel filter (included with this valve) is actually larger than the opening in the bottom of the gas tank (just ever so slightly), so you'll have to grind the tank opening with a dremel tool or steel file to allow the filter to go into the opening. Our complete HCP630SET (below) includes a bolt-on grinding template so you'll know exactly how much metal to remove.

All-in-all, this is a both a great value and a fine idea. It forever eliminates the dreaded "leaking petcock" problems associated with 20+ year old factory petcocks for a price just slightly more than what it costs to rebuild a factory petcock. On the downside, you will have to remember to turn this unit off or on every single time! And, once you modify your tank (by enlarging the petcock opening), an original petcock will never seal up properly to it again (or, not without alot of effort on your part to "shrink" the enlarged hole!).

550/650 (except Turbo)/750 models:

HCP630SET34 Complete aftermarket FUEL VALVE KIT, contain everything you'll need to replace a factory XJ550/650 (except Turbo)/750 petcock. Includes the HCP630 fuel valve, the HCP99 adpater plate, the HCP632 mesh in-tank fuel filter, the HCP1281 tank grinding template, a single HCP81 intake manifold nipple CAP PLUG, and a single HCP542 cap plug PINCH CLAMP.
$ 44.00

HCP630 Aftermarket FUEL VALVE ONLY, as used in the above complete kit. Includes the HCP632 in-tank brass-mesh fuel filter.
$ 25.00

HCP632 Aftermarket brass-mesh FUEL FILTER for the HCP630 fuel valve, filter only.
$ 11.00

HCP99 Aftermarket fuel valve-to-tank ADAPTER PLATE, includes the plate, plate-to-tank mounting screws, screw washers, die-cut plate-to-tank gasket, and a packet of gasket sealer/thread sealant. This adapter plate fits all XJ550/650 (except Turbo)/750 models.
$ 17.00

HCP1281 aftermarket tank opening Grinding Template....a bolt-on thin aluminum plate that has a hole the exact size and placement needed to enlarge the petcock opening hole in the tank to accept the HCP630 fuel valve listed above. Takes the guesswork out of this critical task! This grinding template fits all XJ550/650 (except Turbo)/750 models.
$ 7.00


700/900 models:

HCP630SET46 Complete aftermarket FUEL VALVE KIT, contain everything you'll need to replace a factory XJ700 or XJ900 petcock. Includes the HCP630 fuel valve, the HCP2981 adpater plate, the HCP632 mesh in-tank fuel filter, the HCP3013 tank grinding template, a single HCP81 intake manifold nipple CAP PLUG, and a single HCP542 cap plug PINCH CLAMP.
$ 44.00

HCP630 Aftermarket FUEL VALVE ONLY, as used in the above complete kit. Includes the HCP632 in-tank brass-mesh fuel filter.
$ 25.00

HCP632 Aftermarket brass-mesh FUEL FILTER for the HCP630 fuel valve, filter only.
$ 11.00

HCP2981 Aftermarket fuel valve-to-tank ADAPTER PLATE, includes the plate, plate-to-tank mounting screws, screw washers, die-cut plate-to-tank gasket, and a packet of gasket sealer/thread sealant. This adapter plate fits all XJ700 and XJ900 models.
$ 17.00

HCP3013 aftermarket tank opening Grinding Template....a bolt-on thin aluminum plate that has a hole the exact size and placement needed to enlarge the petcock opening hole in the tank to accept the HCP630 fuel valve listed above. Takes the guesswork out of this critical task! This grinding template fits all XJ700 and XJ900 models.
$ 7.00


OEM Fuel petcocks: note that although these will physically bolt up to your tank, they are completely different from your original petcock in every way imaginable:

fp16) OEM Yamaha replacement Complete Fuel Petcock. Brand new unit comes complete with the internal filter. This unit fits and looks "somewhat" the same as an original XJ-series petcock, but it is a completely new unit and no component (internal) parts will interchange between an original petcock and these units. Surprisingly, these units are still made by the Taiyo Giken Company, who supplied the original petcocks on the XJ era bikes....

HCP626 OEM Complete Fuel Petcock. The vacuum and fuel outlet port nipples point directly out towards the back of the bike. This is the most useful orientation for these outlet pipes. Includes the in-tank filter and the petcock-to-tank sealing o-ring. Fits all XJ550/650 (except Turbo) and 750 models. NOTE: petcock mounting screws and their washers are NOT included!
$ 79.00

HCP625 OEM Complete Fuel Petcock. The vacuum outlet port nipple points directly out towards the back of the bike, while the fuel outlet port nipple faces backwards and at a 45-degree angle outwards. This is a slightly odd orientation, but it does allow for slightly more space for the fuel line to be routed clear of obstructions, especially when using an aftermarket in-line fuel filter. Includes the in-tank filter and the petcock-to-tank sealing o-ring. Fits all XJ550/650 (except Turbo) and 750 models. NOTE: petcock mounting screws and their washers are NOT included!
$ 65.00


HCP627 OEM Complete Fuel Petcock. The fuel inlet and outlet port nipples point directly out towards the back of the bike and tilted upwards at a 45-degree angle. Includes the in-tank filters and the petcock-to-tank sealing o-ring. Fits all XJ650 Turbo models. NOTE: petcock mounting screws and their washers are NOT included!
$ 118.00


HCP628 OEM Complete Fuel Petcock. The vacuum port nipple points directly out towards the back of the bike (rather than being angled as the original) and the fuel inlet port nipple is tilted upwards at about a 45-degree angle and is NOT angled towards the center of the bike (as original), nor is the fuel inlet nipple as long as on an original petcock. Surprisingly, besides these minor differences, these petcocks look exactly the the originals. Also, the changed inlet pipe orientation results in being able to install the rear petcock-to-tank mounting screw easily---on original petcocks, you basically have to almost hacksaw the screw off to remove/replace it or the fiber sealing washer! (a wonderful feat of factory engineering!). Includes the in-tank filter and the petcock-to-tank sealing o-ring. Fits all XJ700 and XJ900RK models. NOTE: petcock mounting screws and their washers are NOT included!
$ 91.00



All of this (and more) over at:

http://www.xjbikes.com/Forums/viewtopic ... t=120.html

 

XJXLEE ...

You hit the nail right on the head.
If the original lasted 25 Years and a New one is 62-Bucks ...
You are talking a whole: ...

20 Cents a Month for a Brand New Petcock that will still be working fine when you Will the XJ-Bike to your Grandchild!!!