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POP SPUTTER (new petcock)

timebombprod

timebombprod

Forum Sage
Got the new fuel valve fitted two days ago, let it sit to make sure no leaks were occurring, and installed the tank and lines lastnight. Went to start today and took me 15ish minutes of messing with the idle and prime setting on the valve to get it to idle by itself. I let it run by itself for about 5-8 minutes before it slowly but surely turned off. I primed it again, turned it back on and it was up idling smooth agagain, another 5 minutes about goes by and boom it shuts off again slowly but surely. I have never had this problem occur other than with the bad autolite plugs but it wasnt to where the bike turns off, and pops as loud as it does.

In neutral or clutch pulled in it can run through rpm no problem, but once under load it acts like crap, 3k pr about when the second jets turns on it's no go I'd literally be jerking around because the bike is constantly giving unstable power.




So two questions

1) could my fuel valve that I bought new be not working? This just seems unlikely to me but when I'd prime the carbs up itd sound pretty close to normal, and it shut off by itself slowly when not assisting with fuel passage.

2) could my fuel valve working properly show that my carbs aren't? Or that they're too lean?


That fuel dump is GONE!

Neighbor just walked by and said it sounds kinda like the ignition but he does have a big truck not a bike, and it has never done this problem before the new fuel valve.
 
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When the bike is on pri, it runs a great bit better but still doesnt have a smooth powerband, its rideable. It will run okay once the bike is primed enough, but it seems to like being primed too much.

I haven't brought the bike past 3k much because the one time I was seeing if itd just be able to go up through the band it was just completely not what you want,

Do all the jets get used when the clutch is pulled in or the bikes in neutral? If I've never had a working petcock and it threw too much fuel in the carbs would that make the bike run richer, I dont think this is the case but I'm just curious. What I'm getting to is tuning the exhaust for the bike it's never been properly tuned with the exhaust being fitted, it is one size up on the main which has shown great feedback, but the rest are stock. I wouldn't think this would make the bike run that bad but I also wouldn't know anything about tuning carb jets.
 
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Its laughable how rough it was, I'm laughing thinking about how ridiculous it was but still not happy that it was happening, I record when i ride I'm gonna see if it's clear at all showing the bike constantly jerk lol.
 
Pet cock can not put too much fuel to the carbs. The fuel to the carbs is regulated with the floats, needles, & seats. I'm not sure, but will think the pilot jets can supply enough fuel to over-rev an eng when it's under no load, ie. clutch disengaged, or in neutral.
 
How does the petcock cause the fuel dump (fuel coming out the emergency exits)

This isn't happening anymore with the new one but doesnt give enough fuel obviously
 
The pet cock won't dump fuel, all the pet cock does is deliver fuel to the carbs, possibly, not likely, flow too little, but can't flow too much. After the fuel gets to the carbs, first place it goes is thru the needle & seats, if the floats are set & needle & seats working properly, they stop the flow of fuel to keep them from over filling the carbs.
 
rphillips said:
The pet cock won't dump fuel, all the pet cock does is deliver fuel to the carbs, possibly, not likely, flow too little, but can't flow too much. After the fuel gets to the carbs, first place it goes is thru the needle & seats, if the floats are set & needle & seats working properly, they stop the flow of fuel to keep them from over filling the carbs.
Click to expand...

Well that's a bummer I guess, i was told I should replace my Petcock and there's no blame on anyone for suggesting but the thing is now is one of the petcocks is definently defective.

The old one seemed to work but the fuel dump would occur, and the floats worked fine and the needles and seats were good but I guess I'll go through them again.
This fuel dump would shut the bike off it didnt necessarily seem like excess fuel being thrown, and the bike would go perfectly fine and one time I stopped and put it on the service stand while running and the fuel dump happened and shut it off again.

Now the bike doesnt dump fuel at all but runs pretty bad, for some reason quieter at idle it seems, and it doesnt like to go through the revs at all under power. And it shuts off by itself when i dont prime it to keep it on.

What the heck

Could this be a fuel jet clog. I have a feeling I'm gonna have to rebuild these carbs myself one reason or another
 
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Update, the brand new petcock I just bought doesnt consistently work, I sucked on the vacuum line and first fuel came out the gas line, then i stopped thinking its okay, then the second time I test, doing the same thing just sucking on the vacuum line seeing if gas will come out the gas line, CLOG. Gonna mess with the fuel valve see if theres a chunk or bit of something in the filter or the passage. I knew something with this fuel valve was up.
 
Then before you take it apart I’d see about getting a refund or replacement. I’ve also read good things about the OEM style replacement petcocks sold by georgefixs.com.
 
cowboyup3371 said:
Do you have an inline filter or just the one attached to the petcock?
Click to expand...

Just the one on the petcock, i redid the tank very early in because it was completely rusted in and since there shouldn't be anything getting into my clean and sealed tank other than gas I just never added one back on
 
Rich82GS750TZ said:
Then before you take it apart I’d see about getting a refund or replacement. I’ve also read good things about the OEM style replacement petcocks sold by georgefixs.com.
Click to expand...

Thankyou for the recommendation! This is the second OEM petcock I've bought off z1 that isnt working correctly, I've heard plenty of good about them so this was very unexpected

What's the chance the two you order are both defective......if this one is and the last one I had isnt then I might have to run through the carbs, but what was happening and how my sparks looked made it seem that the old one aswell, is defective.
 
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One question before I go forward, when testing the petcock, is it supposed to give a constant stream of fuel just by a constant pull of air or does the air pulsate?

I ask this because I tested the old one, and it does the same, but also I pulled apart one real quick to see how it works, and I see the spring and gasket and see that it pulls in a pulse, releases, then pulls in again.

Now, the second one is defective! It does not release for atleast 5 seconds and sometimes wont release at all. But the first one, released the instant u release pressure meaning it has a consistent pulse.
 
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Suck on vacuum line & fuel flows, quit sucking & fuel stops. It's as simple as that. No pulsating nor nothing. When mounted on a bike & working properly, bike not running there is no vacuum so no fuel, crank the bike & it sends vacuum to pet cock & fuel starts flowing & keeps flowing as long as the bike is running. Turn bike off, vacuum stops & fuel stops flowing.
 
When vacuum to petcock the fuel it flows constantly, like water from an open faucet. With no vacuum there is no flow like water from a shut off faucet, not even a drip.
 
Okay then two out of two are forsure defective!

Is a manual petcock switch possible on these? I have to mess with the petcock more than i would with a manual one anyways. If it's not a good idea for these bikes I'll get another vacuum, but I'm gonna have to get the other one I'm done with z1 for now
 
I just noticed that the old one I have works only on reserve, its a constant flow of fuel but once on normal no fuel is passing through.
 
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