85' XJ700n Rebuild Issues

I'm going to work on cleaning out the rest of my tank before I get my carbs back. I talked to hogfiddles and I'm pretty sure he suggested Phosphoric Acid. I found another forum that has the steps to do it, I just wanted to run to past you guys since I trust you all more than some other random forum. Link below, its a few posts into the thread:

http://cx500forum.com/forum/technical-help-forum/20455-phosphoric-acid-gas-tank-cleaner.html

 

Nope. The file size limitations are the same for everyone. Upload to YouTube and link it.

 

Okay so I've been working with hogfiddles (the XJ Master Wizard) getting my bike back up and running. I've run into a few different issues and have been looking around the forums for the solution and I found it, but I don't quite understand how it works. I have a leaky petcock on the XJ700n and it leaks from the fuel line in RES and ON (sound familiar anyone? lol) apparently this is typical in these bigger bikes with the replacement petcock parts that I got when I got the bike 3 years ago. I've been reading about bending the metal disc in the petcock...but can someone post images of this being done because I'm confused as to the process I guess.

 

http://www.xjbikes.com/forums/threa...a-vacuum-fuel-valve-w-pics.25058/#post-213052
I read this and some other posts around the forum, but I haven't found one that really explains how to do the metal disc bending with the socket over it as well as I'd like

 

There was also something Chacal noted about the shape of the plunger and that something need to be modified, or squeezed into the bore tighter.... or something--- I don't remember what it is.. just a vague recollection hitting me at the moment. Hopefully he or someone will chime in shortly

Dave

 

Ya that's what I had found searching around, but I don't want to screw anything else up.

And as I was doing my wet set yesterday with the PVC rig, it all worked out, but for some reason the bowls wouldn't fill when I went to the second round of tweakage. I rapped on the bowls with a screwdriver, but the floats should have been in the lowest setting with the needles on top of the flange and everything should have been ready to fill, but when I set the tank to prime for some reason none of the carbs bowls would fill. I double checked the filter and fuel lines and nothing was plugged. I suspected the needles sticking, but since they were in the lowered position when I reinstalled the bowls it should've been good. (I didn't take the carbs off the PVC rack so I didn't have to keep releveling them every time)

 

And I was thinking that the plugs probably just fouled out since it's been running so rich/lean lately, so after I do the wet-set I'm going to clean the "arc-space" between the ceramic/brass and the spark-flange (very technical terms I know) with sand paper or steel-wool and then I'll get a better spark and maybe that will solve my cylinder issues.

 

NOTE: there is an issue with some of the XJ700 and XJ900 petcocks (mostly the XJ700 and XJ750-X version) where the o-ring seat for the diaphragm plunger was not drilled "straight" (perpendicular) to the mounting face for the diaphragm.......this is possibly why the original petcocks used a hollow o-ring, that would deform more easily to compensate for this (slight) mis-alignment situation......although this issue normally manifests itself as a drip-drip-drip type of leak, rather than a "pouring out" type of leak.

On the affected petcocks, we’ve found that it is necessary to slightly “lengthen” the plunger shaft distance, and the best way to do this is to use an appropriate sized deep-well socket, and place the plunger shaft/tip down into the well of the socket……so that the round metal disc will be sitting on the top of the socket opening, with the plunger shaft down inside the socket well.

Now, take a small hammer (or hammer-like object) and GENTLY tap on the tip of the shaft sitting above the disc, thus “dimpling” the disc in the center JUST SLIGHTLY and thus moving the plunger tip (with the o-ring) “closer” to the seat in the petcock body. This dimpling should BARELY make a concave surface out of the round. previously-flat disc.

As mentioned, some of these petcocks actually had their o-ring seat drilled slightly off-center (or cockeyed) in relation to the plunger shaft…….original plungers used a HOLLOW o-ring that could easily deform to make up for this slightly off-kilter orientation of the shaft vs. the seat. The replacement plungers use a standard, solid o-ring and this cannot deform as much as the original hollow o-rings do. By dimpling the support disc, and in effect “extending” the length of the plunger shaft, the solid o-ring can take up any tiny amount of slack caused by this non-alignment issue.

 

The fuel valve needles should not be sticking shut.... I put fuel valves with metal tip needles in them.