carby problem -_-"

[aussie-zr]

alright lets keep this simple, 2000 zzr 250, carb floods with petrol tank on, take tank off and run bike, runs perfectly, any ideas anyone?

I remember someone showing me once that if you could blow air through one of the hoses coming out of the carb ( i cant remember if it was the vac hose or the petrol... ) that you have a blown/broken/f%&ked something or other... so i blew into both the petrol and vac hose, can blow through both no resistance, well theres a bit of resistance on the petrol hose but i assume it just cause im blowing into the fuel bowl and the air has to push through the fuel... so would i be right in assuming that being able to blow through my vac tube with 0 resistance is a) bad and b) the cause of my problem

any help will be appreciated

[aussie-zr]

Eerm just incase someone ever has the same problem... I pulled the carbs out, opened bowls, and cleaned jets and bowl etc, here's the interesting part... Whilst inspecting the float valves for ANY damage watsoeva (even tho inreplaced them 3 days ago) I started to think that these new needles were smaller then the original.. Even though they were specified to suit the zxr, so I grabbed the ones that came with the 20 dollar carb rebuild kit and compared and the cheap ones were slightly bigger orrr the right size, changed them over, and while I was in there I changed the pilot screws, only to find that the spring, washer and o ring was missing from both and they were both screwed in to about a quarter turn off tight, put new ones in with springs etc and adjusted to tight then two and a half turns back each, replaced bowl seals and went ova all tubes to check if seated properly, put carbs back in and.... Yes she runs beautifully now, no flooding no idling problems no nothing, I swear it's running better then when I just got her back from a mechanic the other day.... My question is, it was obviously the needles being to small and not seating properly causing the flooding but how was my bike even running for the last 4 months since I bought it with the pilot screws pretty much screwed to the limit, like to the point where the tips were sticking out just after the butterfly valves..... She ran fine and never had a problem with idling and all.... Can someone explain? I knew nothing about carbs before pulling mine apart and putting back together 315748393 times in the last two weeks so its a mystery to me..

[csmith12]

Dunno, but that is an interesting find. Change in weather? Full moon? Light reflect off Venus through some swamp gas?

Odd....

[Jinx250]

It's amazing that bikes will often run fine with the strangest settings. This is why carb tuning is part science, part black arts. And also why jetting is 100% bike specific.

[Motofool]

Check if the tank is releasing the pressure of the fuel that vaporizes inside.

The simplest test is to open the cap and see if the engine improves.

If the valves of the bowls are closing in a marginal way, it could be that the hydrostatic pressure (due to the height of fuel above them) make them leak when the tank is half or full.

Have you measured the actual level that the fuel reaches inside the bowls and have you compared it with the specs?

Just a couple of ideas to check.