pet cock problem

I have an 82 xj750j. I just got it this spring. The problem is the pet cock pings and bangs with the engine rpm. The only thing I can come up with is the diaphram in it is bad not holding the vacuun from the motor. Does any one know where to find one. Seems like you can find one for any other yamaha of this vintage but mine is not listed. Is there one from another bike that will work on mine? Thanks for the help

 

Readin the posts there is apparently a repair kit?

 

Are you sure it is the petcock and not that the filer tube which attaches to it inside the tank has come loose and is pinging and banging on the inside of the tank?

 

Didnt know there was a filler tube inside the tank that attaches to it. What does the filler tube do. I havan't been able to find on inside there as of yet. It is definately worth a look though. Will get back with you in a bit and let you know. Thanks

 

Just another tought. Is the diaphram supposed to hold Vacuum? Mine seems to bleed off rather quickly. Thanks again for all the help.

 

nope not the tube. It is firmly attached. Any more options. I did notice that where the vacuum line plugs into the petcock there is a little disk in there. Is that supposed to be there? Appears to be used a s check valve as such.

 

I also noticed the little disc when I sisassembled mine. According to xjowners mailing list, the kawasaki repair kit is the one to get (I´ve pasted a post from the aforementioned list, summing up some other posts):

"Anyway, for what it's worth, I've tacked on a few relevant comments
from others below:
===================================================
>I'm missing too many parts on the existing XJ700XN petcock, and I'm
>open to suggestions: I've heard tell of a Kawasaki petcock that will
>"bolt on".
>What I've hear, and will look up, is that the -diaphragm- is replaceable
>by a Kawasaki part number.
>Patrick Geerlings posted on March 7:
>Order Kawasaki Partnumber (not a joke!!) 43028-1015 Diaphragm assy
>(4A) (should cost about US$10,-)
===================================================
>The Kawa Part Number is: 43028-1015 Diaphragm assy (4A)
===================================================
>The part# is 43028-1015 Diaphragm assy (4A). It's not a very expensive part,
>I only paid EUR9,- for it. When you order you'll not only get the membrane
>but also the plastic part that's between the two rubber membrane's
===================================================
>For US members I looked it up.
>Part Number: 43028-1015
>Description: DIAPHRAGM ASSY,TAP
>Price: $8.35
>http://www.ronayers.com/main.cfm
>They charge a flat shipping rate of $7.00 if you order just this one item or
>if you order an entire bike worth of parts.
===================================================
>order KAWA part number 43028-1015 Diaphragm assy (4A)
>and replace the original diaphragm for the kawasaki piece.
>It works better than any after market replacement kit.
>Mind that this part number only contains the diaphragm, not the parts of
>the petcock that are on the other side of petcock. (round rubber with four
>holes, washer etc....those parts can be ordered from the yammarobber
>though)
===================================================
>order KAWA partnumber 43028-1015 Diaphragm assy (4A)
===================================================
>My theory is that K&L have supplied undersized o-rings on the spud in
>their kits. I wasted $25 for my kit.
>Somebody figured out that a $10 Kawasaki diaphragm is applicable:
>#43028-1015 Diaphragm assy (4A)
===================================================
>For those of you that are interested, I managed to obtain a Kawasaki
>replacement
>part for my XJ650RJ.
>Part# 430281021 - This the Diaphram Assembly including:
>-Square Plastic body
>-2 square rubber gaskets
>- Metal Plunger with small O ring
>Source Kawasaki Bike is the KZ650-H2 '81-'82 H1/H2)
>Price: $16.26 Cdn Incl Tax
>-Source - Cycle World East, Toronto
===================================================
>it is just the diaphragm that is exchangeable. But that is the part that
>mostly goes bust.
>I found that the K&S replacement kit does not fit the X: the diaphragm
>doesn't seal off at all. So use a regular replacement kit for the parts that
>are located just underneath the fuel selector lever and the kawa diaphragm
>as a replacement for the original one.
>Cost might run up to about $35,- all in total.
>The part number of the diaphragm is 43028-1015
===================================================

Here's what I can summarize from all I've read:
1) The Kawasaki petcock part referred to definitely 43028-1015 with
Diaphragm assembly (4A)
2) Apparently the diaphragm assembly is what always fails and that
part is interchangeable with the Kawi part
3) Depending on who you talk to, there may or may not be additional
parts in the Kawi kit
4) Depending on who you talk to the extra parts may or may not be
interchangeable as well
5) Depending on who you talk to the kit can be anywhere from $10-$40
6) Everyone conclusively agrees the Kawasaki part is better

It's worth a try and I'll probably end up buying both the Kawi part and
the crappy K&L part just for some further comparisons just to see how
things compare specifically for the Maxim-X.

Sorry about the length of the post but I thought it could use some
summarization.


HAP
'86 XJ750XS Maxim-X, Waterdown, Ontario, Canada
Maximum Maxim-X: www.skylinc.net/~hap/maxim-x "

 

thankx for the help. Will try the kl first. I have a mic to get the o-ring diam, as mins does not leak right now. It only bangs around. I will let everyone know what I find. Looks like everyone wants to know the o-ring size. o-ring would be a lot cheaper fix than a whole diaphram.

 

To help with the troubleshooting, if it is getting gas with the petcock in the "ON" position then the diaphragm is good. The Kawasaki part # is for the diaphragm only. The K&L kit will have a diaphragm that fits but the oring has been problematic. The Kaw part# was given originally to help XJer's who couldn't find the K&L kit for their XJ.

 

The carbs do get fuel when the petcock is in the on position. Everything seems to work fine other than the petcock being noisy. It looses its vacuum and then makes a pinging noise throught the fuel tank. Sounds like a hollow sound when tank is at 1/4 and a lower hollow sound when tank is full. Very strange. More annoying than anything else. The vacuum leak cant be good for the motor either.

 

Greetings samsr

Another experiment that you might try is to pinch the vacume hose with some kind of clamp and put the petcock in the prime position. This will allow the fuel to flow freely while you isolate the vacume from the petcock. If your noise is eliminated then this would confirm your diagnosis.

 

it should hold a vacuum , or its leaking otherwise.....

 

Hi.

I bought a K&L petcock kit for my xj700 from Sirius, only thing that fitted was the diapragm the O rings were oversized and a waste of time. The vacum did not work, at least juice still flowed when the petcock was on prime. Have to say I was not at all impressed with Sirius. When I complained I had an e-mail back asking what part's did'nt fit and that was it heard nothing since.

Had a problem with an order from Motorgrid and they were very quick to put it right.

Mick Faighaigh.

 

I appreciate all the help. The noise does go away when vacuum hose is pinched. Guess I will be getting the diaphram. I all ready replaced the orings and such. will let you know what I find. thanks again.

 

ok , when you fit the new diafram check the hose for a no leaks too