hi all, I have a 92 cbr and this is my first bike so I don't know a lot about bikes. was riding today when the engine cut out, started again after a few minutes, then done it again but luckily managed to get home! it felt like fuel starvation, so I have just taken the tank off (which is full by the way), but my question is when I turn the fuel to on should the petrol just flow out? because I couldn't get any to come out. I even sucked on the it to see I could suck some out but nothing, strange thing is I can blow into tank but not suck out of it. is this how is should be or this where the problem lies? thanks in advance for your help

Adam

 

Is there a rubber hose from the side of the petcock,
to below the carbs, going into the back of the engine?

If so, it probably uses engine vacume to operate the petcock.
So the fuel valve is "off", if the engine isn't turning over.

As opposed to a 3-way valve on the petcock.
Up-reserve supply/ down-main supply/ sideways-off.

Possibly, your fuel filter is partially clogged.
There should be one, on the big rubber hose coming from the bottom of the petcock.
Before it goes into the carbs.

Another possibility is dirty/partially blocked carbs.

The final possible, general cause is a regulator/rectifier (r/r) beginning to fail.
As it heats up it starts to "choke" the electrical current to the coils.
Coils can't fire the plugs and the engine begins to stumble.
After it shuts down the r/r cools down and begins to work again.

Do a bit of research on the above issues,
and get back with your results/further questions.

Hope this helps, Ern

 

i had the same problem with my 93 F2 it was the diaphragm in the petcock there is a simple fix for it you can get a rebuild kit a new petcock or bypass the vacuum portion of it totally if you do decide to bypass it be careful make sure to shut the fuel off every time you are not running the bike as fuel could leak through the and fill the cylinders so i was told i did the bypass on my bike (not saying that you should just that it is a option and it works so long as that is what is causing your problem in the first place) also if you do bypass you will need to plug off the vacuum line that comes from the cylinder #1 if fuel has sat in the bike for a period of time the it may be clogged like madhattr said. ethanol is known for gelling up carbs.... the stuff sucks imo. also the r/r are pretty common to "burn out" they can be tested at the battery to see what your output is with a volt meter if it is the r/r you can get a aftermarket one from e-bay for pretty cheap mine was burnt and that's where i got one if you do need one try to get one with cooling fins. hope that is some help to ya let us know how you make out or need more help good luck

 

Yes there is a thinner pipe going to the engine somewhere, but it also has the 3 way switch thing that you turn up or down or off. I think the R/R has already been replaced as it has cooling fins on it. I don't think it has a fuel filter, well I haven't seen one

 

So I have bypassed the vacuum bit by reversing the spring. Went for a quick ride and it actually ran better than ever. So I'm assuming either there is no vacuum being created or the diaphragm is knackered, although I could not see any splits and it worked when I sucked on it to create a vacuum. Will just have to see if it does it again with the bypass

 

glad to hear you got it figured out just dont forget to plug the vacuum port on cylinder 1 and to shut the fuel to off when not running the bike

 

It sounds like you might have it figured out, hopefully you can replace the petcock without too much cost, or repair the diaphragm assembly on the cheap! Just bear in mind, that with the diphragm always open, you might want to turn the petcock off when you're not riding, so that if you have any issues with stuck float valves in the carbs, intermittent or otherwise, you won't flood the engine with fuel, AND, you'll need to block-off that vacuum nipple on cylinder 1, as it will put things a wee bit off with it open.

Also, just so you know, your bike is not "missing something", regarding the fuel filter - the F2 did not come with an inline fuel filter, only the petcock screen in the tank... any F2 that has a fuel filter, is that way because somebody installed one.

 

Just bought a 92 also...also wondering about the fuel flow. Previous owner changed the jets, bigger I assume, ran great for about 1 mile of test then died. Hasn't ran since. Turns over great and with choke on I don't smell it flooding.