TOPIC:

I am afraid that i have to chime in on Nessism K&L complaints, I just rebuild the petcock on my Gpz750A1 with a K&L kit and of some reason it takes a long time until the petcock closes. I havn’t timed it but after the release the suction on the vacuum tube it spills out 5-6cl before it closes shut.

I have since I rebuilt it changed the spring (original part) but it didn’t do much difference. There is something fishy with the diagram or the o-ring as it take so long, we timed it on an other bike and it took 3 sec and less than 2cl before it closed.

/A

martin_csr wrote: Thanks. that's very disappointing. Have these problems been reported to K&L? obviously, the shims have.

When the master cylinder kit issue occurred I contacted Z1 Enterprises where I purchased the kit and they basically told me to pound sand. Very disappointing. That's when I took matters into my own hands and fixed the piston on my lathe. After that experience I didn't bother to report anything. Oh, and I've got a good size pile of brand new K&L valve shims that I'm now afraid to use. I was thinking about bringing them to work and checking hardness to see if I can measure anything different. Just haven't gotten around to it. It would be nice if there was someplace that we could send the shims for inspection.

Last thing, I just bought some new K&L float needles to replace those on some Mikuni CV carbs I'm rebuilding and the spring is pretty weak - it doesn't hold up the weight of the float. The OEM needle springs hold up the float no problem only they cost an arm and a leg.

I guess part of the problem is the price pressures from china. A year or two ago, Z1Ent stopped carrying the K&L fork seals. I asked them about it & they said the other brands are cheaper & people want cheap. doh.

That's a good point Martin. I think the whole online shopping experience is the main culprit here because we search for a kz "gizmo" & 64 matches return. Instantly i'm going thru the list for best deal, fastest or free delivery but we don't get the touchy, feely experience to compare quality of the side by side parts. So price rules until you receive the made in ROC part & see i got what i paid for.
Maybe there should be a simple Good, Better, Best rating for parts? I'd gladly pay more & know it'll work right the first time.

Well, my mail box was literally over-flowing with parts deliveries today and among them was the parts for the petcock rebuild. Yay!

Then I opened them all up and laid them out on the workbench and ran into a snafu:


Diaphram (A) is original. It fit through plastic part (B) and then into rubber cup-like piece (C).
The new diaphram doesn't have a part (C) but it does have a rubber O-ring. I guess, I can see how this would still work by replacing the (C) rubber cup part with a simpler O-ring, however, the shaft diameter of the new diaphram is larger than the original and so the new diaphram will not fit through the plastic plate's hole. If I slip the O-ring off, I can just barely get the tip of the new diaphram to fit into the plastic plate's hole.
I'm further confused by another issue which is not shown.
On the backside of the plastic part it is smooth-flat unlike the front side where there's a recess for the metal plate of the diaphram. The backside fits snug up to the body of the petcock but the petcock has a recess for that rubber cup (C) to fit into.
So, I envision that rubber cup seals fuel from the plastic plate and petcock body but with the new diaphram, there's nothing but that O-ring on the "backside" assuming I could press it through the hole in the first place. Thus, I believe that if I were to have assembled it, the plastic plate would leak around the perimeter because that rubber cup isn't there.

Maybe I should just consider that Suzuki part?
I looked back online and every single diaphram I can find, has this thicker shaft section with the small O-ring instead of my KZ's design.

Is the new diaphram supposed to separate? I noticed that it has two layers of rubber and they're separated by a fraction of an inch space. I can't measure it though. But it made me wonder; is this new diaphram supposed to somehow unscrew or pull apart of something and be installed sandwich-style to front side and back side of the plastic plate and then compressed together? This would seem to seal-off the backside of the plate against the petcock body.

At least the new air filter fit and my new fuel lines and vacuum lines fit.

On my 750 petcock the plastic part B fit between the different layers of the diaphragm. Those parts don't look like OEM though so good luck to you.

Your bike has what I call the hat diaphragm --- that rubber piece looks like a top hat.
The diaphragm plate hole is too small for the later diaphragms.

The replacement diaphragm is one piece --- the o-ring plunger is supposed to fit thru the hole of the later diaphragm plates which have a bigger hole.

I would get a replacement petcock or manual fuel valve.

Okay, so the the original petcock will only work with that "top hat" style plunger part then?
That is, if I replace the diaphram with [ This exact diaphram ] would it work or no?
All the diaphrams I can search for look like this style but that one includes the plastic plate already sandwiched between the rubber. I just don't know if that small rubber O-ring will function the same as the older style top hat plunger?

It's a shame, that people can advertise this crap as fitting my bike and then be totally wrong.

Or is the problem my petcock is not OEM? Is that what you meant Ness? In your list of parts above, the diaphram looks like this one but it's just a small picture, not a link to the actual part, so when I searched for that part number I found lots of these diaphrams and they all look exactly the same and pretty much all cost the same (within a a couple of bucks anyway)...

If the Suzuki one will work I'd go with that. Sellers will be more than happy to take your money if it fits or not.
Steve

I don't know, but I'd guess not. just a guess. someone over at the KZ650.Info site may know. there's a topic over there somewhere but I couldn't find it. doh.

So I just figured out how to "request return or refund" on eBay. Fingers crossed this works, unlike the parts themselves...

I just have to figure out now if it's better to try and rebuild this old petcock or outright replace it with Enhanced's solution above.

Did you try test fitting the new diaphragm to see if the plunger would block the fuel flow opening? test fit without the plate or cover. just curious.