Problems with my CBR 600 F 1993 - question

this is really helpful!

-when it does manifest the problem it dies after a few minutes. Sometimes that means I am still warming it up and the bike is parked, some others it means that I am already at the first traffic light…

-it does it both if left to idle and both if I am giving it some gas on and off.

-no electrical oddities I am aware of

-the bike does not start again at all. sometimes I had to wait up to an hour and in the meantime try several things (choke on/off, fuel tap on/off/reserve, throttle on/off). when it does start it is really random and don’t know what causes it to work again.

  • never tried to make it happen while idling, but will try! didnt think about it…

thanks Big Red!

Ah, this is useful - will it always eventually die if left idling and untouched? If so this sounds less like a mechanical issue, but could feasibly be temperature-triggered… Certainly it’s a useful thing to be able to tell a mechanic, who may be able then to leave it idling while he gets on with making tea or something, and can then measure the state of the bits and pieces once it’s cut out.

Do you have an immobiliser or an alarm fitted?

it doesn’t always die if left idling, actually most of the times idles perfectly! just today at work I turned it on again for a few minutes, no problems. But now I really don’t know what to do… should I bring it back home and then to the old mechanic again?
Or should I go to JapandGerman who already told me that if the bike doesn’t show any problem, they can’t do ****? :crazy:

btw…regarding fuel pump…

  1. my mechanic said (I asked him) that my bike doesn’t have one
  2. I just looked where it’s supposed to be according to a video posted here in this thread, and I am not finding it…
    sorry for dark pictures but since the bike is parked among other bikes didn’t have a lot of possible angles to take this pic.

now I am really confused! fuel pump or no fuel pump? :hehe:

I am no expert but looking at the pics I just uploaded and at this one (comparing pic of my bike I just took with yours) I think I really don’t have a fuel pump :doze:

Last year when I had starting issues with my CBR, I took it down to the OMC with a Haynes manual for an afternoon.
Worked very well for my whole weekend trip to Wales afterwards!
We worked our way through all the usual issues step by step, cleaned all the electrics and it seems to have done the trick. Can’t imagine how much that would’ve cost if I had taken it to a mechanic.
They also helped me fix my steering problem, can’t recommend enough if you can spare some time to fix it yourself.

I also had problem with the regulator/rectifier. Totally burnt and wasn’t charging the battery properly. Apparently a common issue, though my bike was super temperamental when the issue cropped up.

Hrm, this missing-fuel-pump thing is odd. I suspect there ought to be one simply because I can find people selling them and bits for them. But the symptoms don’t sound to me like those of a missing fuel pump (which you’d expect to manifest as fuel starvation issues).

If you’re interested in being able to work on the bike I’d second blu’s recommendation of the Oval, else I think you’ll want to find someone who knows early-'90’s CBRs well enough to say for sure whether or not you ought to have a fuel pump (and they might have an idea of what’s causing your issue). Perhaps in the apparent absence of such a local mechanic there’s a more appropriate forum (though do come back!) - I know Biker’s Oracle is often recommended for the more boring Hondas of the era, for example, and this isn’t the most technical bike forum out there (we’ve a stereotype to maintain!).

thank for the recommendation blu!

Unfortunately I don’t really have that much time to spare to do it on my own… plus with my expertise :ermm: I’d surely need more than a day…

the problem you had with the regulator/rectifier, what symptoms did you have? Was it something that happened even while you were driving the bike?
in my case either it starts and it goes well, or it starts, and a 3 min later, it dies. There is no in between…

btw are the regulator and rectifier the same thing?

Hi again Big Red S,

thanks for the support in this! It already helped me a lot, especially narrowing it down.
The thing with the fuel pump is weird indeed and I am gonna check on a cbr forum what they think… maybe will try to ask davidsilverparts too, he should have a clue I guess.

the Oval mechanic, I had been there months ago. they were nice enough, but I really don’t have time to solve it myself especially because I know that a) it would take a long time b) I wouldn’t trust my own repairs and prefer paying a professional for that… :Whistling:

I am however starting to believe that the problem might lie in the fuel tap. The mechanic said he cleaned it and everything but if I look at the symptoms it makes sense that it’s a faulty one.

day one: crank the engine, engine starts normally, warms up, off I go, no problems whatsoever.
day two: same
day three: same
day four: crank the engine, engine starts normally, warms up, dies at some point (either while still parked or just started), doesn’t start again at all (engine cranks but it doesn’t actually start). I do think that it just doesn’t get any fuel anymore even if I opened the fuel tap and it just starts and goes for a while on the fuel left in the carbs before I closed it.

what do you think?

I’ll keep you guys posted.

No, thanks for the problem! When the forum goes too long without a broken bike for me to wonder about I get into petty arguments about noise complaints :slight_smile:

Anyway, the very sudden death is all that makes me suspect it’s not the fuelling, but that’s not so hard and fast. The Oval will supervise you to make sure you do it competently if you like, but, yeah, you do still need to put the time in.

Does your fuel tap have a normal and a reserve setting? Does changing between those alter the symptoms at all?

haha makes sense :slight_smile:
when the bike dies, after that, I always try several things…reserve tap, on, off, choke on, off, middle… throttle on, medium, off… nothing works.

Regulator/rectifier is 2-in-1 component i believe and apparently you replace it every couple of years, just a known fault.

Bike one afternoon wouldn’t start and had to push start it. Over the course of a week and a bit it would either start fine or not start and i’d have to push-start it.
It would work fine but once of twice die at the lights or something (when there is no throttle and not enough power to charge battery at idle.
Eventually the battery died completely because there wasn’t enough charge due to my short trips.

Take it to a reliable mechanic and he/she will fix it for you swiftly. It sounds like the fuel tap is faulty or a fault within the fuel delivery. A decent mechanic will source the fault and fix it. Scorch is highly recommended on here, so is OMC if you want to get your hands dirty.

And we collect bikes now too, saving you a 14 hour stop/start trip to Watford :wink:

mmm ok :satisfied: tbh it sounds slightly different from my issue. haven’t had problems in cranking the engine and the battery is fine (I think…)

it’s the ‘swiftly’ that I am doubting…with these on and off problems I am afraid to end up paying a fortune and not even solving it… a little bit like shooting in the dark…

Hi Scorch :slight_smile:
if you see post above… I am afraid of how long and how expensive this could be. running out of funds for this bike… :pinch:
how does your pricing system work with picking up the bike? depends on the zone?

thanks in advance!

ps: not to forget… do you think this is a solvable thing without me leaving you guys a fortune? :hehe:

An hour or so on Thursday morning spent poking it while I drink my morning tea won’t cost you much :slight_smile: I’m a big fan of the kill switch theory, if your contacts are suitably grubby and corroded, then a bit of damp in the air could well be pushing them over the edge. I don’t see this as an expensive repair, more a moderate fee proportional to the head scratching I do. I’ll see you tomorrow.

Guys, just an update!

The majestic Scorch solved the problem (fingers crossed! :slight_smile: ) - it was mostly a lot of **** in the tank, in the fuel tap and in the carbs. Mostly gunk and rust.
Bike seems to be going fine now and I am super happy!

So, a well deserved shout out to Tim @Scorch. Super helpful, super professional, super efficient!

thanks Tim,


But you haven’t answered the original question on the fuel pump :ermm:


i hope you solved this, however i used to have the 92 model and had the same identical issue:

the problem is the vacuum diaphramm in the fuel tap, 100%

there is a security system in the fuel tap, even if the fuel is open it only comes down if sucked, there is a hose that goes from the left part of the engine to the fuel tap, when you start the engine it creates a vacuum that open this diaphramm, letting the fuel down.

with the years this diaphramm (or the spring attached to it) can be corroded and this will not allow the fuel to go to the carbs, so few minutes and the bike is dead!!!

it took me months to understand what the issue was, and it is so easy to solve:

you need to open the fuel tap and change the diaphramm and spring with a new one, online you can find the kit (it’s the same as the cbr 400 or vfr400)

however, there is also a quick temporary fix:

if you look at the fuel tap you can see a sort of breather little tube on the bottom part,

you start the engine normally and block this breather tube with your finger for few seconds, this will help the vacuum process and the bike will be fine (been doing this for few months before i eventually bought the kit and it worked everytime)

I hope you solve this issue, it was so annoying and i understand how you feel…