cbr1000fl
50000mi
as new
symptom : a devil to start when not ridden for 3 weeks+ eg after winter even on full choke
idle uneven unless very very warm
starts on the button when warm or ridden recently
seems to have difficulty to pull fuel into carbs
facts/ done:
no slippage of alternator shock absorber ( replaced for new )
battery fully charges and spins perfectly
new replacement carbs and clean inside
inline filter installed to stop gunk
petcock works
pulls like a train when warm
plugs and spark ok

note: if i bump it it wne cold it it will start 1st bump...

annoying to me...

look forward to hints...
regs paul

 

that's a bit of a dilemma,
everything that should of been checked has been,
you say she will start straight up off a bump start but not off the starter, this makes me think battery, do you leave her on a trickle charger when not in use (try charging the battery the night before you use her), it take a fair amount of battery to turn over and fire a cold bike,
im sure someone else will have more ideas.

 

indeed im flummoxed
the battery is a gel type and is full of juice and cranks quite fast
for my money its a problem of pulling in enough of the motion lotion quicker into the carbs
again if there is a whizz out there the input is welcome
pau

 

might sound a bit daft but what positions do you have on your petcock, I think the mk2 is vacuum (correct me if im wrong) as I have a mk1, is there a prime position on the petcock do you start it on prime or in the on position,
I had an old xs with vacuum and it did the same when left a while and I had to start it on prime and switch it over when she got going, its just a thought

 

I have a 1991 CBR1000F with only 6K miles on it, and it does the exact same thing when not started in 3 weeks or more. It takes me 3~5 tries on the starter button to get it to sputter to life (on full choke) and only responds to throttle inputs after a solid 5 min warm up. Carbs are clean, and I just rebuilt the petcock with a new seal kit. It acts like the float bowls are very low, and it takes three or four tries on the starter to open the petcock under engine vacuum to refill them. My theory is the ethanol-blend fuels in the US aren't very stable and the alchohol tends to evaporate quicker, leaving less than optimal fuel in the bowls that has to be blended with new fuel from the tank when it's started.

 

You need to check if the enrichner slide is pulling the enrichners out fully out. And like Brian states above, the quality of fuel these days suck. I did the stick coil mod, went up in the jets and installed a Li-ion battery. Last week It fire right up after setting since September. The jetting stopped the lean condition stumble also.

I think the stick coil mod and rejetting are a must to run the crappy fuel.

 

Crappy fuel is right. We've been lucky here until the last few months. Now we have joined the crowd, as all stations here have gas diluted with ethanol.

As for hard starting after sitting, my '91 does the same thing. After winter storage it takes several tries. I put it down to fuel evaporation from the bowls. Perhaps the jetting and stick coil mod is something I should consider.

During riding season it never sits long enough to worry about though.

 

I have an '89 model and have very similar issues: if left for even a few days when the weather is colder (never gets cold in Sydney smile...), it take a few attempts at cranking over with full choke to get her to go.

One thing I noticed is that she will start straight away with no choke, but will only idle for a few seconds, and will die with any throttle opening.

I wondered if others who have this same hard-to-start-after-a-lay-off "condition" have seen the same thing? What could it mean??

 

Had that issue with my 87 - pulled the plugs cleaned and gapped them - did the job
also I put her on the center stand and rock her a bit to get the floats to move, take her
out put some good fuel and your favourite carb cleaner in there and let her rip for
4 or five miles.

 

Gel battery type does not suit the application here. The gel ones are good at storing the energy for a very long time, that's why you have them in small scooters and electric bikes.

Starting current is just something different and the GEL type won't ever give it to you. First, change the battery (AGM type are the best, they produce starting 200amps!!!), secondly.. look at the starter. Take it apart, clean it, inspect it, don't overgrease it when putting it back together, don't overtighten the bolts, leave them almost loose so the starter rotates really smoothly.

The problem that occurs is that the starter consumes too much energy and weakens the spark. I know it from own experience. Sometimes it is so bad that you end up with no spark at all, and if the bike is sat and the battery might be a little bit weaker it can only get worse

You can do a little test here... when you guess it is not going to start, use a car battery to help her, if it fires up right away, then you have the answer.

The pilot adjustment is crucial for starting as well, I recommend using colortune sparks to sort it out properly.