i just replaced the plugs last week ran like a mad man, then 2 days ago, it just hit a brick wall and like when i open the throttle it just dies. so i checked the petcock and no fuel was flowin, so i cleaned that out. ran for like 5 mins. took a s*it now. i was also wondering if on the bottom of the tank where the 2 nipples towards where the battery is, one just looks like a breather hose and one is just a nipple on mine with no hoses or anything? are they all like that or am i missing something? i want it to run so bad, please help!! i was reading the jets could be clogged, how to clean??? and where exaclty is the "fuel filter" on the bike, cuz theres nothing about the fuel filter in the clymer book!?! any help is good help. and i just wonder if it needs a new petcock. my dad said when i pulled away while it was runnin it smelt rich. buut i dont know how to lean it out

 

if there's dirt in the system and it was blocking your petcock then it could be that dirty fuel is clogging up other stuff... i dunno.

Maybe clean out the entire fuel system and the carbs/jets, that'll probably help.

Here's a nice write-up.
https://cbrforum.com/m_311016/tm.htm

you can check your jets while you're in there.

 

Ya start with the easier stuff... the fuel tank... check it and or clean it out, your fuel filter is on the petcock. did u see the mesh thing the size of a pen. See if that has resedew dirt or rust on it. if so start by cleaning the tank. Or if you think the tank is good then go to the breather tubes. And yes you are missing a small tube but it just hangs down im not sure what the purpose of it is. I dont think it is a big deal that you are missing it, just stop by a hardware store and find a 2 foot long rubber tube to replace it. make sure the breather tube is not clogged. I have not heard of that happening but check it out. Then if still not working it may be time to take ur carbs off and clean ur jets. And also Im not sure exactly what the symptoms were but if it is not running then it may be ur battery. Good Luck

 

I FIGURED IT OUT!!!!!! RUNS AWESOME!!!! ok. well i found there was NO fuel filter on the bike. so i checked all the lines for kinks and none found. so i checked the lines for build up. so much **** in the lines, it was disgusting (wish i had pics). cleaned out with 2+2 carb cleaner. found started a little better. so cleaned out the carbs found lots of **** in them. put an inline fuel filter on and fired her up. ran, but odd. only runnin on cylinders 2 and 3. so i traced the 1and 4 coil back and found the connector right off the coil was loose connections. fixed fired back up. AMAZING. but hey thanks for all the suggestions but if anyone else has problems like this check the bowls on the carbs.