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What??
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Discussion Starter · #1 ·
Im having some trubble with my bike not getting fuel (i think). The bike is an cbr f2.

I was just thinking about how it works when fuel get to the cylinders. Is it just gravity feed and pushes the gas from the tank to the carbs? And then what?



Is the gas vacuum controled in the carbs to the cylinders and how does THAT work?




My bike has spark and only runs on starter fluid, it got gas in the bowls. Iv cleaned the jets..
 

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Have you checked the pilot screws? You maybe running way to lean so there's not enough gas to have it fire
 

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ShamanFighter
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the pilots are separate from the jets. they'll be more than likely capped off if not they may have d shaped screws or flat blade screws.

also what air box are you running. to get fuel into the cylinders you need air pressure
 

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Make sure the little passages at the opening of the carb around the outside aren't blocked off at all. Make sure your fuel lines don't have any air leaks or anything either.
If the carbs are dirty at all, a fairly easy way to clean them is to soak them in a pinesol solution.

The carbs are usually fed by gravity from the gas tank. Often times there is a low pressure, vacuum operated fuel pump since a portion of the gas tank usually sits below the carbs.

Fuel is sucked into the cylinders from the carbs on Bernouli's principle. As the diameter of the carb decreases, air velocity increases, causing low pressure, which sucks the fuel in.
 

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What??
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Discussion Starter · #8 ·
All plugs have clear sparks, but more like a redish than blue. All sparks are a bit black. The two right ones looks like this:


But there is only oil at the threads.

So do i need a new valve gasket?


Next up is to take a look at the carbs!
 

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Here to F stuff up
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first things first, you need to strip the carbs of all the seals you can short of separating the bodies and blast every passageway with carb cleaner and compressed air if you have access to it. http://cbrforum.com/forum/f2-tech-93/carburetor-cleaning-tuning-101-a-96888/


take those two jets out, blast and soak them, take the retard child d shaped screw out at the bottom of that pic, and blast through that passage, which is linked to the idle jet and one of the air tubes up top.



blast through all those air tubes also, as theyre all linked to fuel passages inside the carb body for the main, pilot and needle. also, what i did to get the float needles to seal better was took some q tips, dipped the ends in carb cleaner, and spun them with a power drill in the float needle seat to polish it and get some of the crud off and let the needle seal again. this will keep the bike from running pig ass rich all the time. also, like in the guide, take the needles out and give them a good cleaning along with the passages for them. thats really all their is to it. then the stock idle screw setting is 2 and 1/8 turns out, and give the carbs a good sync and a new set of spark plugs. also, be careful not to overgap your plugs. i made that mistake like a dumbass, and couldnt get the thing to even start. dont gap anymore than .035
 

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Here to F stuff up
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also, make sure you have the vacuum line hooked up for the petcock. those have vacuum operated petcocks, which are a pain in the ass. take that apart and clean it and make sure the diaphragm isnt torn or anything. if you want. you can switch the spring inside it to the other side to make it work just like a regular gravity fed petcock instead of vacuum. but that's really preference.
 

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What??
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Discussion Starter · #11 ·
first things first, you need to strip the carbs of all the seals you can short of separating the bodies and blast every passageway with carb cleaner and compressed air if you have access to it. http://cbrforum.com/forum/f2-tech-93/carburetor-cleaning-tuning-101-a-96888/


take those two jets out, blast and soak them, take the retard child d shaped screw out at the bottom of that pic, and blast through that passage, which is linked to the idle jet and one of the air tubes up top.



blast through all those air tubes also, as theyre all linked to fuel passages inside the carb body for the main, pilot and needle. also, what i did to get the float needles to seal better was took some q tips, dipped the ends in carb cleaner, and spun them with a power drill in the float needle seat to polish it and get some of the crud off and let the needle seal again. this will keep the bike from running pig ass rich all the time. also, like in the guide, take the needles out and give them a good cleaning along with the passages for them. thats really all their is to it. then the stock idle screw setting is 2 and 1/8 turns out, and give the carbs a good sync and a new set of spark plugs. also, be careful not to overgap your plugs. i made that mistake like a dumbass, and couldnt get the thing to even start. dont gap anymore than .035
Thanks i just saw this thread! Really good guide. Thank you.
 

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Discussion Starter · #12 ·
I guess the screw at the bottom is the pilot adjustment screw, which would have a D shaped head but star works much better for me..


The tip looks like this and i dont know if its ok or not.



The fuel filter is not original and is about 4mm in diameter, could it be to small?
 

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Here to F stuff up
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as far as i know, these bikes actually didnt come with a "fuel filter" in the regular sense of the word. they only have the sock in the tank. and for that screw, as long as the tip isnt completely smashed or galled up, should be ok. just make sure its clean and the oring on it is in one piece.
 

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Quackenbush Qustom
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i got an f2 for 150$ about a year ago and it was "blown up" thats whaat po said atleast. replaced the cam chain tensioner so it didnt sound blown up anymore and as far is its running issue it was the fuel line. it looked good but when the tank was put down the line was kinking. so if you let it sit for a while it would get an I.V. drip of fuel and eventualy fill the bowls enough to start then stall. after unkinking the fuel line it always started right up but didnt run "well" until i replaced the inline fuel finter po put in and flushed the tank. after that all good. then cleaned and synced carbs an got even better. always seems to be the small stuff.
 
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