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Just giving an update since its been a couple days. All I can say is the bike is riding fine and doesn't have this stalling issue when clutch in and downshift for now. As stated this doesn't happen all the time and it only happened twice. Lets see if this happens within another 4k or so.

I have heard that CBR300R/F people are having the same problems as well... So, I guess it's common for this engine?
 

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my cbr250r went thru an engine cut-of phase
during first periods of ownership [used, almost new]
within which the only difference to later cut-out free
years was beginning using higher octane petrol
[shouldnt be a factor] and failing to go thru
the recommended start up procedure..

last motorcycles not, ecu managed, not fuel injected..
so i would start up as for carburetted hondas
including blipping throttle, and not allowing revs
to drop to the 1500 they will settle to, if allowed..

mine were typically after acceleration then shutting off
throttle and cluth in.. for eg, uphill, [under load]
accelerating then car in front hits brakes, causing
me to brake, throttle off, clutch in..
the situation i was able to replicate [once]
was accelerating up my home street in second
after entry turn, then throttle off, brake,
clutch in for final arc across and up before
backing into the kerb of my park..

this is the same report as previously here
on this long running subject..

at first i thought it rider error, being new to this
honda and after a break from riding, but that
was a false assumption [lifelong honda rider]..

the best i can make of it including from member
advice here etc, is ecu mangement of lean tending
fuel injection, including quick shut off of fuel
when throttling off, as part of fuel economy..

at least i was able to deliberately replicate that
in my regular home street ride..

one thing there being that i had to deliberately
and fully throttle off,, as after learning that
motorcyle, i was not shutting off throttle
completely.. only a small thing, but
apparently a factor..

if that was a general reality [for me] then it wasnt
a conscious thing, as in making allowance for
engine shut off.. my riding and throttle use
were more or less normal, nothing special..
in the replicated cut out, i shut throttle
fully, snapping it shut..

the cut out phase [not a consistent thing at all]
faded out after only two identifiable changes,
switching to 91ron no ethanol petrol,
and using startup routine as recommended
by members here [had no owner manual]..

which i did religiously thereafter including
with [replacement for 'black beauty'], a new
cbr300ra, which has only 500km up
but has started first touch every time
[like 250] and has never cut out..

repeating that start up [yet again]
dont touch throttle..
neutral, ignition on, wait til she cycles thru,
which you will hear, then press starter..
revs will go to 2000rpm, then slowly
lower to just over 1500rpm, then
finally settle on 1500rpm in a
steady 'heartbeat' [hear that too]..

then you can take off..
some like to wait til one bar
indicating coolant fluids are
up to that temp. some take off
riding easily til their bar/s appear..

seven threads from search 'engine stalls'
on cbr300r forum.. different contexts in some..

go to cbr300r forum enter 'engine stalls'
in 'search'..
 

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last motorcycles not, ecu managed, not fuel injected..
so i would start up as for carburetted hondas
including blipping throttle, and not allowing revs
to drop to the 1500 they will settle to, if allowed..
Yes, it is important to let the engine and computer to do it's thing on start-up. Let it sit and idle for at least 60 seconds while finishing gearing up.
 

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Yes, it is important to let the engine and computer to do it's thing on start-up. Let it sit and idle for at least 60 seconds while finishing gearing up.
I don't and my bike rides fine. I don't notice any difference in behavior whether I let the engine idle for some time or not. At the next light the engine will idle normally at 1.500rpm so there also doesn't seem to be a calibration issue. Besides the manual doesn't state anywhere that one should let it idle for a minute before taking off. No one would let a car idle for a minute before taking off so why should a motorcycle require it?
 

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Just throwing my experience with this shut-off problem in as well (owned the bike since new, no mods):

I had this happen first at 2700 miles, coming up to a red light. (right after that experience, I found this thread and realized I wasn't the only one to have this happen). Then it happened a few hundred miles later and again a couple hundred miles later, preparing to make a left turn on to my street. Last time it happened was about 4-500 miles ago. I now have 3900 on the odo.
 

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I don't and my bike rides fine. I don't notice any difference in behavior whether I let the engine idle for some time or not. At the next light the engine will idle normally at 1.500rpm so there also doesn't seem to be a calibration issue. Besides the manual doesn't state anywhere that one should let it idle for a minute before taking off. No one would let a car idle for a minute before taking off so why should a motorcycle require it?
This. If you feel anal about it, 5-6 seconds after start the oil has already reached the cams and head, so drive on off. No reason to sit and waste fuel.

Shutoff happened to me once in 23k miles, and never again. Never changed my riding habits (including clutch-in coasting and throttle cutoff) and did all I could to replicate it. I'm also running a Leo Vince Corsa exhaust so my bike runs even leaner than stock, and it's never done it again. This leads me to believe it's more than just a lean fuel decel condition.
 

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Nothing can happen with the fuel computer in the first 60 seconds since the O2 sensor is not up to temp.
It's running from predefined maps for cold start and probably "learned" conditions from the previous ride time. Nothing adaptive though from the O2 sensor, but it does have the TPS, ECT, and MAP sensors for certain instant start adjustments.
 

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The point is that letting it idle for a certain amount of time before riding off doesn't do anything magic to the adaptation. There is no adaptation possible until the O2 sensor comes up to temp which may never happen at just idle.
As was my case in point, for "predefined maps" and "prelearned conditions". But that the fuel is indeed still metered in a less precise way, erring on the side of safe and running a bit rich. Long term fuel trims aren't updated until the O2 sensor is heated and the engine is up to temp, and idling will not improve anything.

Which also goes back to my original point, that the stalling has to have more involved than just basic fuel metering to cause the decel shutoff. Almost wondering if the root cause is related to ignition.
 

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im not claiming any specific causative factor here,
just responding with experiences/conditions in
my cut-out 'phase'..

whateveritis, the greater the input
the better the over-view, the greater
chance of finding or knowing..

for me the idle period is only while revs drop
to 1500, which is about the time it takes for
helmet, gloves, mirror alignments and
a few steady breathes before away..

usually before first temp bar..
dont advocate idling for
the sake of idling..
 

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There is no other root cause other than a decel shut off program that resumes injection at too low an rpm. When all tollerences meet in a perfect storm (warm engine but cool oil which is splashed up by the decel) the bike stalls. Kawasaki fixed it immediately in the USA Ninja300's with an updated fuel ecu. Honda never acknowledged the problem. My bike only did it twice and never again in 17,000 miles.
 

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There is no other root cause other than a decel shut off program that resumes injection at too low an rpm.
Untrue. There are many factors that could cause this and many nuances we can't be entirely sure of, many of which I already mentioned. Engine temp, air temp, humidity, TPS readings, timing, etc. Since it was never formally addressed by Honda, all we have is speculation, especially since it's so hard to replicate.

When all tollerences meet in a perfect storm (warm engine but cool oil which is splashed up by the decel) the bike stalls. Kawasaki fixed it immediately in the USA Ninja300's with an updated fuel ecu. Honda never acknowledged the problem. My bike only did it twice and never again in 17,000 miles.
When my bike stalled, it was nearly at the end of my commute, after a 30 minute stint at 65 MPH on the highway. That oil was anything but cool, and oil temp has nothing to do with the fuel shutoff. We're also comparing apples to oranges, as Kawasaki did an entire recall on the 2013 ECU's, so who knows what the issue really was, as the ECU controls both fueling and ignition.
 

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All Honda had to do was increase the programming value of where fuel injection resumed after decel fuel shut off by 500 rpm. Problem solved. Good job Kawasaki for stepping up for it's customers and addressing their same issue right away. Too bad they couldn't just flash the ecu without replacing everyone of them just for a change on programming.
 

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I have not read all the posts on this topic as I do not have the problem. Has anyone tried resetting the TPS closed position setting?
This happens when resetting the ECU. Can't say if anything really helps or hurts or neither, since the issue happens so few and far between.
 

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just a head's up. i have had those random shut downs in last 32000 km but not so much that i would worry however off late while coasting or de-acceleration at low rpm it used to sound like the bike is farting. not exactly misfires but hollow fires.

i isolated the issue to Fuel filter which sits right below the tank. costs 350 INR ( roughly 5$) . ideal change is at 10k-12k miles. change if you haven't my issues is rectified also engine seems to be more smoother than before. the old one had crap filled in it. if done 10k 5$ ain't a big investment. give it a try either ways it will eventually be replaced. might solve the problem.
 
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