What is the hose on number 3 caburator holder ?

I took off my xj 750 caburator for a long time so i forget where the hose is
It's on number 3 i don't know what and where to connect the things .I sure that is not a fuel hose but i forget its. Once i've to noticed spark plug
number 3 look pale white than the other i thought the hose is concerned.

 

That hose goes from the carb boot to the vacuum pipe on the petcock.

Dave F

 

Thank you guy . But i don't know its what for?

 

Petcock on an XJ is vacuum operated. It needs vacuum from the engine to open and let some fuel go down to the carbs bowls when the petcock is on ON or RES. Actually, this vacuum hose could be connected to any carb, but it is usually connected on carb #3.

 

Just a side note. I got a non vacuum petcock a couple weeks ago. Haven't got the bike done yet but don't see why it wouldn't work. Ill just plug he hole up like normal.

 

Non vacuum or manual petcock will work for sure. You just have to plug the vacuum bar of the carb #3, then make sure the petcock is ON when you ride and OFF when you don't, just in case your float needles aren't closing properly

 

yea iv left them on a couple time with my dirtbikes, woke up and could smell the gas in the kitchen lol. i have a shirt that says i love the smell of gasoline fumes in the morning so its fitting...lol

 

Could be waking uP to your garage burning down, lo

 

one can only hope, this house is full of asbestos and mold, and i think the paint is so old it still has lead in it...

 

Insurance against the Petc0k leaking and the Carb Floats failing and gas over-flowing or filling the Crankcase is cheap.

A Briggs & Stratton Fuel Valve Shut-off can be bought at a Hardware Store.
Mount it right next to the Petc0ck.
"Paint" the Hose Clamps with Black Nail Polish.
Paint the RED Valve with some Black Polish leaving the end of the Valve RED and the Shut-off virtually disappears.

::: Petc0ck With Aux Shut-off Valve On JX-750FM :::

 

Your spark plug color is a direct result of your missing hose. You are sucking in air from #3 carb boot. You may also be getting detonation on that cylinder also. You need to fix that quick. You can go to the local auto parts store and get vacuum hose for $0.cheap, or you can get vacuum caps for $1.cheap. If the cap, just cap the connection on the boot. If you go with the hose, you run from the boot to the petcock (the smaller connection) and you will want to move from PRI to ON. This will also allow your reserve to work.

There maybe problems with the petcock and carbs that would allow fuel to drain into your crankcase, so keep track of your gas mileage and oil level closely.

 

Thank all you guy.My petcock is still draining the fuel nomatter ON or Res But motor is not running.Shall i plug on a #3 carb boot?

 

Your priority should be to order a rebuild kit for your petcock or a new manual petcock then go buy and install a cheap fuel valve as per Rick recommendation if you are not planning to fix your petcock soon.

 

Thank you Quebecois59 .That's a great idea

 

you could follow this:
http://xjbikes.com/Forums/viewtopic/t=2 ... epair.html

 

The "Do-it-yourself" Instructional and Pictorial submitted by bigfitz52 is a comprehensive guide to rebuilding a stock petc0ck.

The Kit, alone, costs nearly $40.00

I believe it is a much wiser choice to invest in a Brand New Petc0ck.
The old one lasted almost 30 years.
You can expect a New one to do the same.

There is, at least, an outside chance that after rebuilding your petc0ck with an aftermarket kit, ... it might still leak.

 

Rick,

I'm curious. What makes you say that? I bought the kit from Len and rebuilt my petcock. I replaced all the seals and diaphrams. I check it periodically to insure it isn't leaking. I understand the chance that it might leak but outside of damaged parts, why would it leak? Knock, Knock, Knock...I seek light.

Gary

 

Original o-ring of the diaphragm-activated fuel valve in the original petcock was tapered. O-ring in aftermarket rebuild kit is a regular, round section o-ring. It wouldn't seal as well as a tapered one, specially when the seat isn't perfectly machined, which was sometimes the case of the original petcocks.

I'm pretty sure I have pictures that could help understanding that, I'll have to dig in my hard disc to find them...

 

"In addition to the shapes of the seals being substantially different, there are two more unseen differences. First, the stock seal is hollow while the replacement o-ring is not. And second, the stock seal is much more pliable than the stiffer o-ring used in the replacement part. These three differences contribute dramatically to the failure of the Maxim-X petcock rebuild kits... but they're not the only problem.
Even if the seals were the same, the plunger found in the K&L kits is also a little shorter than the stock plunger. The difference isn't much, but it's enough to prevent the o-ring in the kit from making a solid seal against the valve seat... but that's still not the only problem.
As it turns out, even if the seals were the same and the plungers were identical lengths, it's the machining of the body of the stock Taiyogiken petcock that's the fundamental, underlying problem"

Found on maxim-x.com site, created by Harald Pfeiffer.










I doN't know if all of these problems also occur with other petcock models, though, but this one is very well documented.

 

The bigger difference is that the original o-ring had a hollow cross section making it much more "compressible."

It IS true however, that not every petcock can be rebuilt; but it is generally more a case of deterioration of the valve seat area than a machining flaw.

Provided the petcock has a good, viable seat and care is taken to ensure the valve piston sits and moves squarely, a rebuilt petcock can and will function just fine. But it takes "upping the ante" precision-wise, to be sure.

 

Mr Pfeiffer also mentioned:

"I suspect that either Yamaha or Taiyogiken may have realized that the machining of the valve seat wasn't as reliable as it should have been and so to overcome the plunger and valve seat alignment issue, they simply installed a tapered, hollow, more flexible seal that would conform to the seat regardless of the small misalignment."

A misaligned valve seat can be seen before ordering a rebuild kit, by disassemblying the petcock plunger and look at the original hollow o-ring: if it is more compressed on one side compared to the other, the alignment is not good. That petcock would most likely leak once rebuilt.

 

The preceding posts by Fitz and Quebicois cover most of the issues presented with aftermarket Kits.

I've had too much trouble trying to keep people satisfied by putting a Kit they bought in an original Petc0ck.
On one occasion, not only was the Plunger too short, ... but the aluminum wafer that positions the Plunger was too large to fit within the housing.

In November of 2006, I contacted the National Sales Rep for TAYIO GIKEN Co., the outfit that manufacturers the Vacuum-operated Petcock's which are standard equipment on our bikes and other Asian-made motorcycle's, too.

After a lengthy conversation, where I explained the difficulty consumers were having with aftermarket rebuild kits not solving their problems (related to their petc0ck's breaking-down with age, leaking and causing a great many problems for XJ-Bike Owners and others) I asked if it would be possible to make a Bulk Order of OEM Rebuild Kits.

The answer was NO!

TAYIO GIKEN parts are protected by Patent and the Company is still under contract with YAMAHA.
Under NO circumstances are they allowed to sell or distribute Petcocks or Repair Kits to anyone other than Yamaha Motors Inc.

That's why I suggest buying a Brand New Petc0ck, ... which does not involve anything but taking it out-of-the-box and putting it on-the-bike.

 

Always learning. Thanks to all.

Gary