The vacuum diaphragm inside my petcock has actuates properly under vacuum.
However, I noticed something. Don't have my camera, so I'll try to explain it:
When the petcock is split and you're facing the diaphragm, there is an outer rim that looks like an o-ring. It's part of the rubber diaphragm.
When blowing INTO the petcock from the vacuum line, I've noticed a small gap between that surface. I'm not sure if I split the material by blowing into it (idiot move on my part), or if it's an intentional part of the design.
I don't know if this is a no-go issue demanding replacement, or if I can just replace and stop worrying.
I've been reading the other posts, including the one where Ben2Go has put the petcock under exploratory surgery. Haven't been able to find anything on it.
My reason for messing with it in the first place:
Kickstand sunk in the dirt. Bike fell over while it was running, and ran dry. Picked the bike up, wiped off the dirt, and gave it a once-over. Ran it around the block, and it died while coasting to a stop. Gas level is good, petcock was set to prime. Started it back up eventually, and noticed gas pouring out of the K&N.
Held the starter, couldn't get it to start. Finally noticed I wasn't in neutral, then got it started. No more gas leaking.
Ran it around the block, and it started bucking when under strong acceleration. Ran fine under normal driving.
This sucks. I'm stumped.
Fuel hoses are routed fine. I've checked and rechecked them.
I really wanted to ride tonight.
At a minimum, I would remove float bowls and check floats for proper movement. if the bowl screws have been replaced with socket head cap screws, you will not have to remove the carbs.
Floats should are fine, I just rejetted. Completely went through the carbs. Couldn't get the color out of the floats, but that's not gonna affect anything.
My tank is clean, so it's not a fouling issue.
I have noticed the intake boots have cracks, so I've got new ones on order. One of them is about half a millimeter to a millimeter wide, so that side's running pretty lean.
But, it shouldn't be bucking like that from running lean.
It acted like it just wasn't getting enough gas at high throttle, which is why I went into the petcock. It seems fine, other than that gap I was talking about. It should have been wide open, anyway, under high throttle. My high-tech "vacuum testing device" showed that it opened without a problem.
Quote from: wladziu on February 11, 2009, 04:35:11 PM
Floats should are fine, I just rejetted. Completely went through the carbs. Couldn't get the color out of the floats, but that's not gonna affect anything.
My tank is clean, so it's not a fouling issue.
I have noticed the intake boots have cracks, so I've got new ones on order. One of them is about half a millimeter to a millimeter wide, so that side's running pretty lean.
But, it shouldn't be bucking like that from running lean.
It acted like it just wasn't getting enough gas at high throttle, which is why I went into the petcock. It seems fine, other than that gap I was talking about. It should have been wide open, anyway, under high throttle. My high-tech "vacuum testing device" showed that it opened without a problem.
My project bike has cracks in the tubes connecting the carbs to the engine and it will barely run at all. I'm waiting on new ones which I hope will solve my problems and make the bike run again...
Don't know what the problem was, but it runs fine now! :woohoo:
Shortened up the lines coming from the tank, to get kinks out of the equation. Ran a magnet around inside the tank, to check for loose debris. (I'm sure that was a big help. :icon_rolleyes:)
Checked all the lines for correct placement. Checked the filler cap to rule out vacuum lock. Made sure there was no gas in the left carb vacuum line. Ran it completely dry to rule out flooding. Slapped the tank back on, and it ran fine in the garage.
Completed the advanced ignition mod while I was at it.
Rode to school and back, a few miles each way. Runs like a pissed-off squirrel. So, I don't know what the problem was. Oh well. Hope it doesn't come back.
Recommend the advanced igition HIGHLY, by the way.
If those cracks in your intake rubbers open up, you could easily fry a piston.