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If I may, I'll add that certain steps (assuring the float system is in fact completed) have been omitted here. And would also like to add that various alternative methods do exist.

Pic of EX250 carb tuning components, I'm actually doing the set today.

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Discussion Starter · #42 · (Edited)
well this has to be said, and this is not a criticism of anyone but a general finding that newbies doing the carbs for the first time get info on how to do the job correctly what to check and what to test. they read the comments and answers pick the one they like, ignore the rest and do it their own way anyway.
no wonder they have to be done several times before success is achieved, all the info is here on the forum but no one seems to read it before pulling the carbs "to have a go", there is one way to do carbs and only one way, properly.
that is why @ducatiman is so good and has complete success because every set is done correctly and consistently.
cut corners, ignore steps, or miss something always ends in failure.
I have been on the forum over 8 years and in all that time it has never changed. guess it never will.
to be perfectly frank as a newbie (any newbie) unless your prepared to read and do the carbs properly the best course of action is send them to done where mistakes are not made.
Hi there. Firstly I am not new to this. My knowledge is 25 years old so I have forgotten a few things like tipping the carbs to set the float levels but i am not a "newb". I have an as yet undiagnosed problem with the float assembly.

Secondly I read every single article on carb tuning here before bothering because EX carbs have always been finicky. I have not bothered to reply to a couple of your posts because you are telling me things I read and have done before engaging this project. I ordered new float pins seals and floats to avoid all of this nonsense. I told you already I have 2 to 3 sets of stock needles and jets. Before i was aware of how bad the problem was I asked about potentially using the dynajet needles as I have the ability to change their height which typically would allow one to lean the mixture, at least for the middle of the throttle. But the mixture isnt the issue... The carbs are dumping fuel. This is 2 different sets of carbs with 3 different sets of floats and needles which leads me to my next conclusion...

All of the float needles have problems. The new ones from the kit i dont believe are good quality. The kit was the cheapest thing i could find and who knows what kind of imperfections might hang them up. I wont make that mistake again. The other 2 sets were factory original and sat in gas filled carbs for years and years. My last attempt set the floats at such a height they should not get fuel enough to operate and still it floods. Not believing all the floats bad and seeing no evidence they take on fluid, this leaves needles.
 

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ok so, for someone with 25 years experience. it seems you forgot 2 of the most important quick tests that would diagnose your issues, 1. requires two fingers a piece of fuel line and pair of lungs, fit the tube onto the fuel line hold the floats closed blow down the tube. instantaneous results. 2. a wet test for float levels once you know the floats are sealing by doing test no 1, where is the problem.
regarding the aftermarket needles sharpen them up and use as a metal scribe there no good at all in a set of EX carbs the stock needles have a special profile not copied on any aftermarket needle. believe me I've looked for some, the nearest is JG but is 5mm shorter so over fuels at WOT. JJ have the length but the tip is 0.5mm thinner so over fuels at idle. just saying not everything is as it first seems.
 

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Discussion Starter · #44 ·
ok so, for someone with 25 years experience. it seems you forgot 2 of the most important quick tests that would diagnose your issues, 1. requires two fingers a piece of fuel line and pair of lungs, fit the tube onto the fuel line hold the floats closed blow down the tube. instantaneous results. 2. a wet test for float levels once you know the floats are sealing by doing test no 1, where is the problem.
regarding the aftermarket needles sharpen them up and use as a metal scribe there no good at all in a set of EX carbs the stock needles have a special profile not copied on any aftermarket needle. believe me I've looked for some, the nearest is JG but is 5mm shorter so over fuels at WOT. JJ have the length but the tip is 0.5mm thinner so over fuels at idle. just saying not everything is as it first seems.
Not sure what your deal is friend but you dont pay much attention as I keep having ro repeat myself. My 4 years experience is 25 years old. Savvy? Obviously you can just put fuel to the carb without installing it. I thought he knew some kinda magic involving string or something.

I like your number 1 test. Never heard that before. You certainly didn't mention it before.

My experience with carbs as you seem quite intreagued comes from when I raced AMA supersport 600/unlimited southeast circuit. I didn't have a team so a group of us did all our own tech. The fundamentals of a carburator arent that difficult to understand. Putting stock jets with stock needles in stock carbs with new floats wasn't expected to encounter much of a problem. When it did I leaned on the best resource in existence for this specific setup. I am not exactly sure what it is I said that has your panties all twisted up but if I unwittingly offended you I am sorry. It was not intentional. There is little mistaking my intentional offenses. I appreciate your help but going forward I have little interest in your personal commentary about me specifically. I will still take any and all advice. Thank you in advance.
 

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hello there. no twisted panties here just an old grumpy git with 60 years experience at this [delete swear word] trying to help by replying to the same questions with the same answers infinitum that mostly seems to go over the heads of those who ask.
why do I/we do it if it's so much hassle well now and again it actually helps someone, finding out how much experience someone has of motorcycles helps to decide how answers are constructed what is obvious to some is a mystery to others. no offence is ever taken or given in the threads that is for sure.
I hope you get it running well soon as I do for all those I/we try to help on the forum, there is only so far one can go without repeating everything. the info is there what is done with it is an open question.
 

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Discussion Starter · #46 ·
hello there. no twisted panties here just an old grumpy git with 60 years experience at this [delete swear word] trying to help by replying to the same questions with the same answers infinitum that mostly seems to go over the heads of those who ask.
why do I/we do it if it's so much hassle well now and again it actually helps someone, finding out how much experience someone has of motorcycles helps to decide how answers are constructed what is obvious to some is a mystery to others. no offence is ever taken or given in the threads that is for sure.
I hope you get it running well soon as I do for all those I/we try to help on the forum, there is only so far one can go without repeating everything. the info is there what is done with it is an open question.
Well i guess what I have failed to get across is that it was my intent to rebuild these carbs that someone jetted back to stock as expressed over and over all over the forum. I didnt just dive in and start asking quiestions. I bought the rebuild kit months ago. I bought a second set of non working stock carbs 2 years ago. I collected multiple sets of oem carb innards. I jetted a lot of carbs back in the day and was succesfull at dialing them in on other bikes. My ex wanted this jetted. I had heard that was a mistake and it was. I had done my due dilligence but I honestly havent opened a carb since the mid 90s. When i first hooked the bike up and it ran on its own without choke I was quite excited. Sounded great. I did not immediately notice gas escaping the overflow. It was a short test. It didnt have coolant in it and I had a lot of electrical work to button up. Once conditions were right to tune it fired up but had telltale signs of running very rich. Thats when I wondered if needles would help. Then the third fire it fould out. I took the plugs out and cranked it over and gas sprayed out. Thats when i realized there was trouble in paradise. I didnt properly diagnose the problem because I wasnt expecting one. It was running... But the more it ran the worse it got. Then I saw all the gas from the overflow tube I had routed. Had I been more observant I would have seen there was an issue and not asked so many dumb questions.

But make no mistake... I did read and was trying to do it the right way. I was patient and not without experience. I have just never had this problem before and wasnt expecting any because... Its not exactly rocket surgery to clean and install the original stuff... I just managed to fail at it.
 

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But make no mistake... I did read and was trying to do it the right way. I was patient and not without experience. I have just never had this problem before and wasnt expecting any because... Its not exactly rocket surgery to clean and install the original stuff... I just managed to fail at it.
unfortunately this is often the case, despite carbs being simple and babies of the 80's they are in fact complex pieces of precision equipment. change any of the parameters or miss something and failure ensues, seen it so often it's biblical.
that is why pods and jet kits are a bad idea, now this can be done just the average joe doesn't have the equipment or skill level to accomplish it.
so one is only left with the option to use stock parts cleaned fitted and tested at every stage of rebuilding them. with added tests before fitting and final adjustments. that is successful 90% of the time.
leave out a step, miss something, not test something and the success rate is at best 40%.
now only you were there to know what was missed we do not. only by offering suggestions and asking some searching questions can it be established what went wrong and at what stage. my money is on a flow test when fitting the floats and wet test before fitting the carbs, either or both of these would have red flagged your issue.
it's unbelievable how many times this occurs on DIY carb jobs. and the main reason so many have do them over a few times. redoing the bits they missed the first time. no biggie just annoying assuming something is correct when it isn't.
 

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@yorkie comes up with a great idea in post #43; blowing into the fuel supply tube on upturned carbs. The weight of the floats will close the float needles, and if all is well should create a closed circuit.

Just last week I was getting a leak on some carbs on a EX250 I'm rebuilding and couldn't tell where the fuel was coming from. Took the carbs off, held them upside down, and blew through the fuel tube. I could hear air hissing at the tube that connects both float bowls together. They needed a replacement tube with better O rings. The float needles themselves were sealing fine.

From here the wet test confirmed everything was OK.
 

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Discussion Starter · #49 ·
unfortunately this is often the case, despite carbs being simple and babies of the 80's they are in fact complex pieces of precision equipment. change any of the parameters or miss something and failure ensues, seen it so often it's biblical.
that is why pods and jet kits are a bad idea, now this can be done just the average joe doesn't have the equipment or skill level to accomplish it.
so one is only left with the option to use stock parts cleaned fitted and tested at every stage of rebuilding them. with added tests before fitting and final adjustments. that is successful 90% of the time.
leave out a step, miss something, not test something and the success rate is at best 40%.
now only you were there to know what was missed we do not. only by offering suggestions and asking some searching questions can it be established what went wrong and at what stage. my money is on a flow test when fitting the floats and wet test before fitting the carbs, either or both of these would have red flagged your issue.
it's unbelievable how many times this occurs on DIY carb jobs. and the main reason so many have do them over a few times. redoing the bits they missed the first time. no biggie just annoying assuming something is correct when it isn't.
Air flows with carbs upside down. New parts ordered.
 

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took the carbs off, held them upside down, and blew through the fuel tube. I could hear air hissing at the tube that connects both float bowls together. They needed a replacement tube with better O rings. The float needles themselves were sealing fine.
had this issue myself @ducatiman pointed me in the right direction, apparently some aftermarket kits use sub standard parts (who would have thought it) turns out the supplied O rings for the fuel rail were not ethanol safe, 3 weeks after a carb clean (with the bike stood) and the O rings degraded and failed.
 

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had this issue myself @ducatiman pointed me in the right direction, apparently some aftermarket kits use sub standard parts (who would have thought it) turns out the supplied O rings for the fuel rail were not ethanol safe, 3 weeks after a carb clean (with the bike stood) and the O rings degraded and failed.
My fuel tube was original, but after 20 years was no longer working as designed. Scavenged the part from another set I had lying around.
 

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Discussion Starter · #55 ·
So if someone could explain to me... Fuel dumps in via the 2 holes at the top of the carb that the black plastic fuel line supplies. So long as there is gravity there is fuel (gravity petcock installed). The float needle blocks the fuel from exiting the middle hole on the airbox side but the pilot jet supplies the hole next door... What is to prevent fuel from exiting that? Dont get me wrong my carbs dump fuel from both and the overflow...
 

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I'm not sure I understand your question. However, fuel should only enter the float bowl via the jet that is controlled by the float needle, which is activated by the floats themselves. This is the same principle as your flushing toilet (the tank stops filling when the water level rises and raises the float).

CV carbs operate on a vacuum, so fuel is sucked up through the pilot and main jets by vacuum generated from air rushing through the carb body. Apologies for my crude description, but there are some great explanations and motion graphics out there on the internet to demonstrate this principle in more detail.
 

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yeah pretty much got it in one. for bit more detail.
photo 1. air jets one serves the pilot circuit. the other goes through the carb body to somewhere near the main jet. (been a while since I gave them a clean. (Gordon may elaborate if required)
photo 2. top ring float vale seat. btm ring idle jet fitting hole.
photo 3. vent tube ports. no fuel should get any where those they plain and simple vent holes. note how high they are above the bowl joint, (where the correct fuel level should be).

BTW. you have not had the fuel line connected to the vent tube have you. if so no wonder it floods how is the float going to control flow if the float valve isn't controlling the fuel flow going in.
 

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Discussion Starter · #58 ·
yeah pretty much got it in one. for bit more detail.
photo 1. air jets one serves the pilot circuit. the other goes through the carb body to somewhere near the main jet. (been a while since I gave them a clean. (Gordon may elaborate if required)
photo 2. top ring float vale seat. btm ring idle jet fitting hole.
photo 3. vent tube ports. no fuel should get any where those they plain and simple vent holes. note how high they are above the bowl joint, (where the correct fuel level should be).

BTW. you have not had the fuel line connected to the vent tube have you. if so no wonder it floods how is the float going to control flow if the float valve isn't controlling the fuel flow going in.
Lmfao... You think a guy with 25 years experience is gonna put gas in through the out door? I am offended.

Completely unrelated... Carbs are fixed.
 

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Discussion Starter · #59 ·
I don't remember if we ever ended up exporting sarcasm to your side of the pond but that was it. Im a complete knob. In fairness I havent done this in a long time. Havent seen the setup in a couple decades but... Yeah. Didn't work that one through. I owe you a pint.
 
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