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Discussion Starter #1
So i just bought a 92 cbr 600f2 rode it home filled the gas tank full. let it sit over night. and i walk outside and see my bike has a fuel puddle under it. found out the leak is coming from the exhaust! Right where the a/m muffler pipe bolts on to the pipe so i unbolt it and pull off the a/m pipe to find that my exhaust pipe is litterally full of fuel!!! Also i noticed my full tank of gas is obviously, completely empty! Please help me figure out why.

note that i found no fuel line or anything else was leaking, everything else is dry. the only place im leaking gas is from the exhaust.
obviously im flooding the engine and its going out the exhaust but why is it flooding?
 

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I had this same problem on my f3 , my carbs where dirty from rust in my tank , and the float levels where way out of adjustment. when the float levels are off the gas never shuts off thus filling your engine then exhuast with fuel.
 

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That's a lot of gas. Consider everything is now full of fuel so you need to replace the oil before thinking about running the bike. You should also squirt a little oil down the plug holes and under the rocker cover before starting. It will be smoky but right now there's no oil film in there which is bad news.

Mainly check the float needles for sealing. Float levels should not go out of whack as they're not really adjustable you have to deliberately bend a tang to change it from standard. (I think)
 

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Float needles and seats are leaking, bad. Hopefully you have not cranked it over yet, you need to get the fuel out of the cylinders before you crank it over or you can hydraulic lock the engine and bend valves. Remove the plugs and ground the plug wires and turn it over. Also, like Amorti previously said change the oil.
 

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Discussion Starter #5
So heres an update i pulled the carbs off and it seems like each carb is full of fuel, and each combustion chamber is full of fuel except for the ones that the valves are open on. obviously thats how the fuel got in the exhaust. so what i dont get is how all of the needles or all of the floats are bad. Like when a spark plug wire goes bad, it ussualy aint all of them it is only one of them and if its all of them then its a coil which supplies voltage to all of them, see what im getting at? But then again i know almost nothing about how carbs work. I have a feeling i just put the petcock in the wrong position, is that possible if not. where should i go from here? Do i tear the carbs apart and what im a looking for idk hope this update helped you else im screwed.
 

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Discussion Starter #6
Float needles and seats are leaking, bad. Hopefully you have not cranked it over yet, you need to get the fuel out of the cylinders before you crank it over or you can hydraulic lock the engine and bend valves. Remove the plugs and ground the plug wires and turn it over. Also, like Amorti previously said change the oil.


I have not turned the bike over i know about hydrolock. and i dont plan to until i have fixed it first so after seeing my last update do you still think its all 4 float needles and seats? and how positive are you? if so how do i chacge them?
 

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Discussion Starter #7
ok so i just tested my petcock. i put some gas in my tank. and put the arrow facing up(?reserve?) and its leaking/ pouring fuel out. then i put the arrow facing left(?off?) and it is still leaking/ pouring fuel out. the i put it in the down(?on?) position and it doesnt leak obviously because i didnt have the fuel level high enough(im not wasting anymore precious gas haha) so it could leak but idk. As much as i learned from good old youtube the petcock shouldnt leak any fuel out in any position without there being a vaccum which i did not apply and it is leaking fuel out. Also im assuming it should not leak out any fuel on the off position wether vacuum is applied or not.
So with that being said do you at least agree with me that i need a new petcock?
Also if my petcock is bad and i let fuel flow into the carbs because of it. Should the fuel still be able to flow through the carbs, into the cylinders, and then into the exhaust pipe? Or is something still effed up with my carbs?
 

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...So with that being said do you at least agree with me that i need a new petcock?
Also if my petcock is bad and i let fuel flow into the carbs because of it. Should the fuel still be able to flow through the carbs, into the cylinders, and then into the exhaust pipe? Or is something still effed up with my carbs?
It's true that if it's an F2 petcock, fuel should not flow without vacuum applied, so the diaphragm is probably shot, but if it's also leaking in the "Off" position, then something's even more wrong.

Once you get the petcock issue sorted, I would still at least clean the carbs to the extent that the floats, and their pivot rods and needle/seats are all moving freely, and not sticking, in case that is an issue as well.
 

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Discussion Starter #9
It's true that if it's an F2 petcock, fuel should not flow without vacuum applied, so the diaphragm is probably shot, but if it's also leaking in the "Off" position, then something's even more wrong.

Once you get the petcock issue sorted, I would still at least clean the carbs to the extent that the floats, and their pivot rods and needle/seats are all moving freely, and not sticking, in case that is an issue as well.
Alright i took off the float bowls and everything in there..the floats, needles, pins, seats, jets, the bowl etc... is surprisingly clean, no sticking of the floats or anything. So im not sure anymore if thats the issue. Im gunna clean them anyways, but could ther be anything else wrong that would cause fuel to flow thru my carbs? I havent took off the other side which has the springs and diaphram in it yet. so maybe theres an issue in there?.
I attatched some pics to show you how clean it was.
 

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Can't work this out in my head. Even if the petcock fails which it sounds like ours has, a healthy set of float valves should stop the problem you've had.

So I have to assume that at least one of your float valves isn't as good as it looks. Only needs one of them to be bad.

Replace the petcock first. If any of your float valves leak it will show up only when running. And if it hasn't done before then good enough.
 

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Discussion Starter #11
Can't work this out in my head. Even if the petcock fails which it sounds like ours has, a healthy set of float valves should stop the problem you've had.

So I have to assume that at least one of your float valves isn't as good as it looks. Only needs one of them to be bad.

Replace the petcock first. If any of your float valves leak it will show up only when running. And if it hasn't done before then good enough.
found out that the petcock i have on there now is not vacuum operated... still leaks though. So i think i would have a hard time find a rebuild kit since i have no idea where this petcock is from. possibly ordering a new vacuum petcock off ebay from china for $27 had to message them to get fast shipping for an extra $30. Which is still a good price.

I was wondering if one of my float valves do leak why are you saying ill only notice when running? couldnt i just fill the tank up with the bad petcock and see if it runs through the carbs again? also i checked the other side of the carb parts and everything looks clean and good in there also. Is there a kit i could buy that has all the parts in it such as the floats, pins, needles, jets, diaphrams, gaskets etc.. if so where could i find it? Ive searched rebuild kits for 92 cbr 600f2 and found nothing. except i did find jet kits for different stages but i dont think that includes everything im looking for. Plus if there is a rebuild kit will i need a stage 1 jet kit since my bike has a k&n filter and a yoshi exhaust muffer?
Thanks for all the help i really appreciate it! good karma is headed your way haha
 

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Alright i took off the float bowls and everything in there..the floats, needles, pins, seats, jets, the bowl etc... is surprisingly clean, no sticking of the floats or anything. So im not sure anymore if thats the issue. Im gunna clean them anyways, but could ther be anything else wrong that would cause fuel to flow thru my carbs? I havent took off the other side which has the springs and diaphram in it yet. so maybe theres an issue in there?.
I attatched some pics to show you how clean it was.

Have you checked the float heights?
Connect fuel to the carbs and see if they leak.
Then tilt them each way until they start leaking, then back to level and see if they stop leaking.
 

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Discussion Starter #13
Have you checked the float heights?
Connect fuel to the carbs and see if they leak.
Then tilt them each way until they start leaking, then back to level and see if they stop leaking.
Alright so i finished cleaning the carbs, put them back together, the floats are not sticking what so ever when moved, i connected fuel like you said and there are no signs of leaking, it only leaked when tilted upside down out of the breather tubes( im assuming that is ok). So as it sits right now the carbs may be back to working order. I will be waiting for the new petcock (paid $19.99 for it with $30 shipping off ebay coming from china)to arrive in the mail tomorrow or at least by monday at the latest. Once i recieve the petcock i will connect everything back together and see if the problem has been fixed. Thus letting you guys know incase anyone else runs into this issue.
 

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You bought a copied petcock from china? Not what I'd have done. That part relies on decent quality materials such as rubber seals and fitting together properly. It is also unlikely to accept Honda original seals when the Chinese ones do fail.
 

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I have been using the china petcock on my F2 since 6 months. no issues at all. The one sold by XF-MOTO have the vaccum line too. if you directly contact them and ask for out side ebay transaction u get a 10 to 20% discount too. Have been buying stuff from XF and very reliable and fast shipping
 

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Discussion Starter #16
Update: I have cleaned the carbs, cleaned the gas tank, installed a new petcock, changed the oil and drained the oil out of the filter, but reused the old filter since it was supposably new and looked new, and hooked everything back up the way it should. Now its time to start it up. I started it up and right away heard a tapping/knocking noise (more in between) not really sure where it is coming from, wether its in the block or the valve train. I let it run for about 10 seconds then shut it off. I noticed when it was running the oil light was coming on and off. So i have a feeling i either dont have enough oil in it or i did slightly dent the oil filter when trying to get it off but i didnt think a slight dent in the filter could cause such bad oil pressure. So now im worried. It didnt make the noise before the fuel leak problem so what the hell. On the oil dipstick it has an indent that idk is about an inch and then in the middle there is a line when checking the oil i had it filled up to the line, should it be higher than that? I put about 3.5-4 quarts of 10w40 motorcycle oil from castrol in it. Do you think its the filter? IDK im baffled! How does it run perfect before the fuel leak and then after i completely clean/ redo the fuel system and put it all back together exactly as it came off ( i have no doubts that i put it back together correctly) cause the engine to tap/knock and have an oil pressure issue? Please help if this isnt a simple/cheap fix im screwed!
 

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Update: I have cleaned the carbs, cleaned the gas tank, installed a new petcock, changed the oil and drained the oil out of the filter, but reused the old filter since it was supposably new and looked new, and hooked everything back up the way it should. Now its time to start it up. I started it up and right away heard a tapping/knocking noise (more in between) not really sure where it is coming from, wether its in the block or the valve train. I let it run for about 10 seconds then shut it off. I noticed when it was running the oil light was coming on and off. So i have a feeling i either dont have enough oil in it or i did slightly dent the oil filter when trying to get it off but i didnt think a slight dent in the filter could cause such bad oil pressure. So now im worried. It didnt make the noise before the fuel leak problem so what the hell. On the oil dipstick it has an indent that idk is about an inch and then in the middle there is a line when checking the oil i had it filled up to the line, should it be higher than that? I put about 3.5-4 quarts of 10w40 motorcycle oil from castrol in it. Do you think its the filter? IDK im baffled! How does it run perfect before the fuel leak and then after i completely clean/ redo the fuel system and put it all back together exactly as it came off ( i have no doubts that i put it back together correctly) cause the engine to tap/knock and have an oil pressure issue? Please help if this isnt a simple/cheap fix im screwed!
The oil light would concern me. 3.5-4 quarts should be correct, I would change the oil filter. Not seeing where you dented it, I would want to make sure you didn't damage the bypass valve. The bypass valve will open druring warm up, because the cold oil will not flow easily through the filter medium which causes a differential of pressure across the bypass valve. It will remain open until the oil temp warms up and the oil viscosity reaches a level that decreases the pressure drop across the filter to a level which allows the valve to close. If the valve was not opening properly it could cause the oil pressure to fluctuate, giving you the oil light, and reducing the volume of oil during warm up, especially to the top end, causing the tapping. I would change the filter, it's a cheap way to rule it out.
 
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Discussion Starter #18
Conclusion: So the knocking went away when i started it up again to take a video of the knocking. I was really surprised and releaved! When i changed the oil i left it drain for like 2 hours and then refilled it so obviously all it need was more time to circulate the oil through the system thank God!! So now that its running again... Problem solved: Main culprit rust in the gas tank( not chunks just alot of surface rust). The rust effed up my petock(which leaked any any position) and then clogged up my carbs (which caused the floats not to close and fuel to flow through the carbs through the cylinders and into the exhaust, and caused a sputter on medium-heavy acceleration). Basically I cleaned out the gas tank with 2.5 gallons of apple cider vinager then used baking soda and water to stop the acid corrosion from the vinegar, then replaced the petcock with one off ebay from china, then cleaned the carbs completely and i also cleaned and lubed my throttle since it was sticking. By the way thank you all for the help! I really appreciate it!

The before picture is what it looked like when i bought it a month ago for $1300 and the after picture is as of right now what it looks like. I put about $300 into it, which makes my total spent on it $1600. I still plan on repainted the tank since he half assed it and maybe putting in black vent panels to replace the steel mesh. What do you guys think i could get for it (its a 92 cbr600f2 with 17,487 miles)? I think i could at least get $2400 for it.
 

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