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CBR250RR Stalling Issue

5585 Views 7 Replies 6 Participants Last post by  Niks
Hey All

First of all wanted to say Hi and great job with the new look of the forums.

I live in Sydney and have owned a '99 MC22 (Australian delivered model) since September last year. I got the bike when I was on my learners and have got my provisional license since then. Have had great fun on the baby CBR :D

I've recently noticed an occasional problem where the bike will stall when the clutch is pulled in and the brakes are applied (such as when stopping for a traffic light). At other times the revs will drop very low and it'll *just* manage to avoid a stall, and at other times it will just drop to the normal idle RPM like nothing is wrong so it's a very occasional issue. I suspect it's a vacuum leak of some sorts but am unsure where to start looking :huh:

The bike was serviced recently with new oil and a filter and the 'vacuum plugs' were also changed, but this has not helped the problem. I also replaced the spark plugs a few months ago. I've currently resorted to setting the idle speed up to around 1800RPM (was 1500 before) as this seems to help avoid the issue.

Any ideas on what is causing this and how it can be fixed?
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Could be the clutch cable needs adjustment as it's not disengaging fully. Does the bike still want to move forward if your in gear with the clutch in?
Does it still stall if your in neutral?
As Tony says - adjust the play in the clutch lever

or raise the idling just a tad
I originally suspected the clutch as well - But it is adjusted so that it becomes fully disengaged when pulled all the way in. Also the bike does not seem to want to creep forward with it pulled in so I'm thinking it should be ok.

The Dwarf sent me a PM while this thread was locked, so I'll post it here so others can see:
The Dwarf said:
Hey Rav, I dont know who or why someone closed your thread.
First off Does the issue go completely when the idle is set at 1800rpm?
does it idle smoothly or does the tacho wobble?

If it does you will need to balance your carbs.

Try idling your bike and just pull the break, with full light on.
Does it stall then?
If so get a multimeter, check that your battery is at about 12.5volts.
If its under 12.4 get a new one.
Also check its making about 14v when reved to 3,000 if its not the reg/rec could be your issue.

hope this helps.
The bike doesn't stall with the idle increased. Sometimes the revs will drop a little below idle when braking, but nowhere near enough to cause it to stall.

In neutral, the revs tend to however a bit around +/- 100-200 RPM around the set idle speed (not sure why this happens). Pressing the brake when in neutral does not make any difference.

When I got the bike serviced about two weeks ago I believe they balanced the carbs and said the battery was at 13.5V, but will double check when I get home.

Thanks all for the help so far :D
I like the sound of dwarf's pm,

My first crash, my bike did the exact same thing, I cleaned and balanced carbs and bam! problem solved.

I am not sure about his electrical diagnosis though.
A mate of mine had a similar problem with a newer bike, it turned out that the negative terminal wasn't properly attached to the battery.
i had a similar problem where the revs would just drop below 1000 and just die....
i actually have my idle set at 2000, bit noisy coz i've got a aftermarket exhaust but the revs never drop low enough to stall the bike when i stop now and the idle is stable whereas it tends to go up and down if i set it lower than 2k
I have the same problem as Shifted. If I set it at I.5k it sometimes stalls
But when it's at 2k it's fine. I have a question though. I sprayed carby
Cleaner In the barbells today and now while riding and I pull the clutch I
Weather to stop or just idle. The revs go to 3k for a couple of seconds before it corrects its self. Could this be a vacuum prob or balancing?
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