Petcock / Fuel Flow Freakiness

[AdamOdes]

Getting the bike ready for winter and here I am flying the 'newbie' flag way up there!!

Bike washed, polished and waxed - check!
Pulled the battery - check!
Gas tank topped of with Stabil conditioned gas - check!

Shut off petcocks and drain carb float bowls - Krikee !!, the gas just keeps coming and coming and coming. What??

Both petcocks are in the off position (handle side of lever to 'off')
Fuel just keeps coming out quick like the petcock is wide open. Same result through each carb.

Am I missing something obvious? Could it be that both petcocks are broken?

Ran the bike for 10 minutes (@ idle) with the petcocks in 'off' to see if it would run out of gas. Just kept going and going and going.

What are the consequences of leaving the bowls filled with gas?

Thanks all and to those who ride year round in warm weather - Enjoy!!

[Materi]

Are you sure the 'cocks' are not in the "prime" position? The lever should cover the function (off, prime, reserve, on) you desire, not the other way around. I only ask because I had an old Honda where it was reversed, and I was confused by this when I was trying to get my bike running.

[AdamOdes]

lever position

Yes, this was confusing at first. I too was used to the honda method where the handle turned the petcock but the other end was used to point to the function.

On the XJ, the handle is covering the 'off position'.

Thanks for the thought.

[Materi]

Dang....sounds like your petcocks are probably trashed. Good news is it's a cheap and easy fix. Bad news is you have to wait for the rebuild kits to get here. In the meantime, you can disassemble them and check the condition of the rubber diaphragm, my guess is yours are torn or otherwise worn beyond functionality. If they are like the ones on my 79SF, in certain instances, you can turn the rubber over and they may regain some or even all function. Do a search on fuel petcocks for great advice on this procedure. You may want to put your bike in your sig so we can tell what you're working on. Winter sucks here also, and we will hardly be able to ride at all. Rather than "winterize" mine, I have grand illusions of a new exhaust system, steel brake lines, new fuze assembly,etc. I'm thinking if I start it every couple of weeks or so to work on it, I won't have to add the stable, etc... Hey maybe the streets will even be clear enough to blow a little arctic wind over "the breeze" and I. Good luck dude.

[John]

Add the Sta-bil anyway. The same fuel will be in the tank all winter, even if you do run it for a while. The treated fuel in the carb passages will prevent any varnishing between winter starts. The bike will run fine on treated fuel.

[skids]

Maybe the oring at the automatic shutoff diaphragm is not seating properly. Pull the vacuum hose off the manifold and blow into it to seat the diaphragm plunger and its oring. I suppose you have the octopus and I assume the mechanism basics are the same as the standards, although they (standard diaphragms) are located at the petcock and not in the octopus.

[skids]

I failed to mention that if your petcocks are in the off pos'n, at least one of them is not sealing properly. It is probably that holey rubber washer gizmo. Sometimes you can get by if you turn it over and rebend the wavey metal spring washer. I think it is also a good idea to sand and polish the contact surface of the petcock valve (handle thing) so that its rough finish can't lacerate the holey gasket. You might be able to get by with blowing into the vacuum hose for now to seat the oring better, but I would disconnect the fuel hoses from the carbs or you might find your crankcase full of fuel if it does not work!

Originally posted by skids
Maybe the oring at the automatic shutoff diaphragm is not seating properly. Pull the vacuum hose off the manifold and blow into it to seat the diaphragm plunger and its oring. I suppose you have the octopus and I assume the mechanism basics are the same as the standards, although they (standard diaphragms) are located at the petcock and not in the octopus.

[Materi]

Originally posted by John
Add the Sta-bil anyway. The same fuel will be in the tank all winter, even if you do run it for a while. The treated fuel in the carb passages will prevent any varnishing between winter starts. The bike will run fine on treated fuel.

Good point...I will add it.

[AdamOdes]

Great advice

Rebuilding the petcocks sounds like the way to go - heck might even be fun. Anyone have a favorite online shop to check out? BikeBandit seems popular. I like how they tied in to Yamaha's online parts dept. which provides you factory part #'s. Slick!


Materi, hopefully your winter upgrades will take your mind off the long cold winter season. Do any snowmobiling? Sometimes I think it'd be fun but nowdays, here in southern WI, we get plenty cold but very little snow.

AdamOdes

[Ken Talbot]

There's another possibility. If somebody before you had a go at rebuilding the petcocks, they might have reversed the 'on-off-res-pri' plates. I.e. - installed the right side plate on the left side petcock, etc. This would result in 'off' position actually flowing prime. When 'off', are your handles pointing forwards? What happens in all of the other positions?

One other thing, I believe there has been some mention of rebuild kits where the metal cylinder in the middle of the diaphragm is too short to actually press the o-ring against the seat to stop the fuel flow. Do you know if the PO tried to rebuild the petcocks?

[fredintoon]

draining the carbs

I have always winterised my bikes by draining the tank & carbs then sloshing a half-cup of 2-stroke oil around the empty tank.
OTOH my son fills the tank, adds Stabil then runs the bike around the block on Stabil-ised gas to make sure the carbs are full of it.
BTW both methods work.
By all means sort out your gas taps but leaving the carbs full of Stabil-ised gas over winter should be OK.
Fred Hill, S'toon.

[AdamOdes]

Mystery machine

Ken
Painfully, i'm finding out that many of the claims the PO made about the bikes history are untrue. The price of the bike was pretty low, so so far i'm still happy with what I have - although i'm confident there are many more mysteries to unravel.

The face plate of the right side petcock does have a dry cakey brown spot on it. Maybe the PO or the PO's PO had a leak and did some incomplete work on it.

The rebuild should take care of any missing, mismatched or defective parts.

We have a little one due to arrive any time now, so the petcock project will probably have to wait till spring. Let's all put our hands together for the good people who invented Stabil!

AdamOdes

[nashville_bill]

You might think twice about leaving a fuel source open all winter. If one of your float valves springs a leak, you will have gas in the oil and on the floor.

[Ken Talbot]

For winter storage, I disconnect the fuel lines from the carbs, and use them to connect the petcocks to each. This way, even if a petcock fails over winter, the fuel doesn't go anywhere.

[chevy45412001]

hey adam

i take it your oil pan is on? good. as for the petcock repair,i went with just buying the rubbers by themselves,as the rest of the kit was a waste to me. The price from yamaha was iirc 12.00 for both rubbers. I did not hear mention of leaving it like that would not be a good thing.Could possibly fill your crankcase with fuel,(don't ask how i know...lol ) So you should fix them asap.