i picked up a 1990 cbr & it is stumbling, missing, & hesitating when i rev it or try holding it at a certain rpm. when i close the choke it dies @ idle, even when its warmed up. i try adjusting the idle screw & dont notice the rpms go up or down. the bike has been sitting for all of last year. i have dumped the old fuel & already ran the bike with new fuel & a fuel/carb cleaner. after the refueling it has ran better but still not good enough. i am going to be pulling out the carbs & cleaning them the for the first time. i feel confident i can do it but what should i look for? is there anything you experts make sure you dont forget or spend extra time on? what should i be careful with? what do you recommend for a first timer? thanks all

oh yeah i already picked up the repair manual for the bike

 

Check out your fuel filter and the fuel cut out valve before you pull off the carbs. You might also need to have the carbs adjusted or "carb sink" done. Also try sea foam in the gas this is almost as good as carb cleaner and it is not as hard on the seals plus takes a good amount less time.

 

sea foam?

i replaced the fuel filter already. the tank is empty now. i can pull out the fuel cut out valve & spray some carb cleaner on it. should i try putting more fuel & the sea foam before I pull the carbs? or just pull the carbs & then get everything back together & try the sea foam when i crank it up?

 

Ya know i had the same exact problem...low power would die out after ya take choke off..i messed with the idle and tried to take some slack out of the throttle...it was a pricey fix but i couldnt of done any better myself....i took it to a dealer and bit the bullet....my 89 rips...its never been that fast since ive had it...sure they gave me new everything..sprocs chain plugs oil....syncd carbs...900 bux later...it was money well spent..so..that would be my fix...i just dont know enuff about moto's to tinker around with em tho

 

i bit the bullet & took it to a local shop on saturday. it looks awesome with them just cleaning it off & what they have already done with it. the smog has all been ripped out, carbs are taken care of, new plugs, new oil, brake fluids, & radiator coolant. they are going to balance the tires, replace the chain because of rust, & my fuel pump isnt keeping a signal. i asked if i should put a slip-on muffler & he suggested repacking the stock canister to save me money. wow i am wondering what this is all going to cost me.. . it was up to $380 but he isnt finished yet. i was thinking about k&n pods & a full race exhaust but i dont know how much money i want to put into it. any suggestions?

 

Did you get your bike back up and running? If so, what was all done and what was the final cost? Just curious, and it might help others out.

Just a note. From what your describing, it sounds like a clogged pilot (idle) jet. Same thing happened with mine. It would roll with the choke on, and would go full throttle, but would die off the line. I didn't want to "bite the bullet" so I got my manual out and dove in. First attempt got me nowhere. So I tore them back apart and was much more thorough. I cleaned everything real well with blasts of carb cleaner. You really have to blast out all the little passages and jets. Rarely will your main clog up, since it's so large, but that pilot jet is super narrow, and just waiting for blockage. After spraying everything with carb cleaner, I followed with a blow gun, drying everything out and using a lot of pressure to clear everything the cleaner missed.

Put it back on and she runs better than ever! But, she's not going anywhere right now. I broke a valve cover bolt off, and have had no luck getting it out. So it's going to the shop on this one. Yup, gonna "bite the bullet".

 

i am starting to have the same problem, so i will try to clean the jets tonight. let you guys know how it goes.

symptons:bike runs when choke is only at a specific spot(about 40% on) and anything else will kill it. the throttle goes up fine when the choke is in position, but it also backfires some too.

 

did anyone ever find a fix for this prob? dies when throttle is given?

 

i think we all pretty much bit the bullet. i took mine to the shop as well but they screwed me over. main jets were probably clogged, but they ended up leaving one unscrewed as a matter of a fact.

 

yeah when someone finds a fix for this let me know too. My 89 cane boggs down when I give it gas and is having the same problem even after I cleaned the carbs. Also my choke will not close all the way. any advice?