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Discussion Starter · #1 ·
Hi, i am having a rought time with a CBR 600 F3 that the owner says it stayed parked some 3 years (i bet this issue wasn't fixed before).
Carbs all cleaned up, shredded into pieces, new carb build kit,venturi membrane very good.
Carb set up like the manual (this one is #135 and #138 jets) and even tried to manually tune the carbs.
Carbs are balanced.
New fuel filter
EVAP solenoid working
Fuel pump working from the tank, and also with separate own tank or the fuel tank pluged directly into the carbs for free flow.

Problem? Bike starts very easily with choke (like every carb bike should do), warms up, revs, and now it gets interesting. after it warms up the revs slowly start to go down and dies. No matter how much idle you give it (until 2500 rpm) it slowly dies. If i give idle more than 2500 rpm the it starts to rev by itself.
On idle bike has a fluctuation of 200-500rpm sometimes.
I've tried to adjust the pilot as in manual (1.5turn) also above until 3.5 turn and also down to 1 turn still dies.
I've had a test drive with the bike, now at 2 turns, and it pulls like it should, so there is spark when it should be on full throttle and also at slow speeds.
The interesting thing is if i slow down to a stop light after some throttle, the bike revs until almost 5000 rpm. and it comes back or not.

I've done hundreds of carbs but this issue is not something i've related, so the ECU seems to work fine, the coils seems to work fine also.
I've thought that the Crankshaft pulse generator sensor could be damaged but that would mean the bike will not work okay when moving, but it does, runs okay.
I've thought that timing chain can be 1 tooth jumped but in that situation the bike will not work ok in moving of lack some power, but it pulls hard.

The only thing that remained to check would be really really tight valve clearence and when gets hot will have zero clearence left.

If anybody has any other idea will be more than welcomed. It starts to get on my nerves checking and double checking everything
 

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You likely are making this MUCH harder than it really IS.

When it gets to this point where it is starting to die, close the choke a bit......or spray some starting fluid into the intake.
If that makes it smooth out, then you are having a loss of fuel OR and excess of air.

Loss of fuel can be from a plugged tank vent or pinched fuel hose.
Excessive air can be from a vacuum leak or from not having a proper air filter on it.
 

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Discussion Starter · #3 ·
You likely are making this MUCH harder than it really IS.

When it gets to this point where it is starting to die, close the choke a bit......or spray some starting fluid into the intake.
If that makes it smooth out, then you are having a loss of fuel OR and excess of air.

Loss of fuel can be from a plugged tank vent or pinched fuel hose.
Excessive air can be from a vacuum leak or from not having a proper air filter on it.

Sorry, but i've stated it starts to die after it gets warm up, operating temperature (and above when Fan hits in) only if let to idle, or at a traffic light when stopping. Hundreds (literally) of carbs/motorcycles done, nothing like this issue.
Also if it was a fuel leak somewhere/or lean/rich mixture, it wouldn't ride that well when pushed hard to the red light, managed to ride it till 140km/h in the city and no problem..it pulls..and it pulls very good
 

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Sorry, but i've stated it starts to die after it gets warm up, operating temperature (and above when Fan hits in) only if let to idle, or at a traffic light when stopping.
The fuel mixture requirement changes as the engine gets HOT.
Also some vacuum leaks only happen as the engine components heat up and expand.

Obviously you don't REALLY know anything about how carb'ed engines work.

IF......you are going to ask for help, you should at least TRY to understand the answers.

Good luck.
 

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Discussion Starter · #5 ·
The fuel mixture requirement changes as the engine gets HOT.
Also some vacuum leaks only happen as the engine components heat up and expand.

Obviously you don't REALLY know anything about how carb'ed engines work.

IF......you are going to ask for help, you should at least TRY to understand the answers.

Good luck.
Sir, you don't have to be rude just because i'm not convinced by your talk, altough it's appreciated.

Not to mention that you advised to close the choke, how runs idle on bike with choke? choke is necessary when start up and a couple of minutes (maybe if very cold outside) otherwise bike idle should hold itself.
Problem appears after around 15min of idle.Who runs a bike that long with choke on?
Also leaking fuel i would probably seen it by having the bike running for so long.
I though posting so explicit issue description will get over the basic stuff.

To a complete rebuild carb and okay compression in the cylinders, it's impossibile to be 500% out of range of the mixture settings no matter how hot it gets, the bike it's standard.

I suspect a tiny tiny air leak somewhere not so obvious to find, this being the only issue that can relate to carb/mixture. And this only because it's starts reving itself if idle is set above 3000 rpm.

I'm posting as if someone had this issue before to hopefully, altough it's very improbably. It's very possible to have a bad pulse sensor (this especially and also had some bikes and cars with faulty) or coils(not so sure for riding okay and accelerating ok), that make the bike die after getting hot when idle only providing weak spark/signal.

Thank you for the kind help
 

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Problem appears after around 15min of idle.Who runs a bike that long with choke on?

Also leaking fuel i would probably seen it by having the bike running for so long.
I though posting so explicit issue description will get over the basic stuff.
SIGH.
I did NOT say to LEAVE the choke ON but to put it on a little bit as a test to see if it runs better.
I also said NOTHING about "leaking fuel".

Is English not your first language ?

I think you need help from a real mechanic.
I quit.......since this "discussion" isn't accomplishing anything useful.
 

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Discussion Starter · #7 ·
SIGH.
I did NOT say to LEAVE the choke ON but to put it on a little bit as a test to see if it runs better.
I also said NOTHING about "leaking fuel".

Is English not your first language ?

I think you need help from a real mechanic.
I quit.......since this "discussion" isn't accomplishing anything useful.
your first post did :) sorry if you don't keep up.
although the problem was not there, found out today the issue and is not fuel/air related :) sorry to disapoint you

also, you just keep being rude :) maybe you are mr. know it all :)
 

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also, you just keep being rude :) maybe you are mr. know it all :)
It seems that we have one single person here who has managed to create TWO accounts and is not contributing anything useful from either one of them.

SO......you have one more chance to straighten up and stop the BS.

Tell us what DID solve the problem or just leave quietly.
Anything ELSE that you do will result in BOTH accounts being deleted.
Understand ??
 

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Discussion Starter · #9 ·
It seems that we have one single person here who has managed to create TWO accounts and is not contributing anything useful from either one of them.

SO......you have one more chance to straighten up and stop the BS.

Tell us what DID solve the problem or just leave quietly.
Anything ELSE that you do will result in BOTH accounts being deleted.
Understand ??
sorry pal, rudeness will get you nowhere, i can point you that is a mechanical issue not a fuel/air nor electrical :) if you wanna get your head around this bike (bet you wouldn't figure out tho) i can send the bike in the US for you covering all the cost :)

now, leaving jokes aside, like i've said, you being a rude person assured not to find the issue in this particular case.

i just hope you will never encounter this issue :)

and by the way, there's no TWO accounts it's just a user name change

cheers mate!
 

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Grinding on the Administrators AND having more than one account are both forbidden actions.
BOTH accounts have been BANNED and this thread is closed.
 
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