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All 650Fs Cb650f won't start

Paul323

2018
CB650F
Feb 6, 2021
Riding Since
2019
Hello, I'm new to the forum and I joined because my 2018 cb650f won't start. It ran perfectly a couple days ago when I was driving it home but the next day when I was about to leave for work it wouldn't start. It kept cranking but wouldn't fire off. So yesterday I decided to pull the air box to gain access to the spark plugs and pull them. When I looked at the plugs they were wet with fuel from me trying to start it the day before so I cleaned them off and left them out overnight to let any excess fuel in the cylinders evaporate. Today I reinstalled everything and tried again but to no avail. The battery is fully charged, I hooked a timing light to every spark lead and every cylinder has spark. My next task is to take a sample from the bottom of my fuel tank to see if any water found it's way in but I was hoping someone here may be able provide some tips. Any and all help is very much appreciated, thank you.
 

miweber929

2014
CBR650F
650 Alumnus
Staff
Feb 13, 2015
Woodbury, MN
Read your manual and follow the flooded bike proceedure. If that doesn’t work I’d try replacing the plugs even though they seem to be working ok.

Let us know how you make out after that.
 

baugustine

2014
CBR650F
Staff
May 21, 2016
Ventura, CA
+ 1 on the fouled plugs. Did you recently fill up the fuel tank? Siphon out some fuel into a glass jar to examine it for contamination or water. Also an inexpensive spark tester will prove out spark quality. I am also assuming normal cranking speed (i.e. compression & valve timing are not off).
 

Paul323

2018
CB650F
Feb 6, 2021
Riding Since
2019
Read your manual and follow the flooded bike proceedure. If that doesn’t work I’d try replacing the plugs even though they seem to be working ok.

Let us know how you make out after that.
I'll try that next, thank you
 

Paul323

2018
CB650F
Feb 6, 2021
Riding Since
2019
+ 1 on the fouled plugs. Did you recently fill up the fuel tank? Siphon out some fuel into a glass jar to examine it for contamination or water. Also an inexpensive spark tester will prove out spark quality. I am also assuming normal cranking speed (i.e. compression & valve timing are not off).
Cranking speed is good, I won't have a chance to pull a sample from the tank until after work. I don't know if this is true for a motorcycle ecu but when I was working on marine outboards I was taught that open spark testers will mess with the the ecu on outboards that are EFI/DFI so I used a timing light instead to be safe. I'm stumped as to why it would start one day and not the next, it did drop to a really low temp where I live the night before though, would that make a difference?
 

baugustine

2014
CBR650F
Staff
May 21, 2016
Ventura, CA
Spark testers do not cause ECM problems. The coil trigger is a digital signal. The timing light only tells you there is spark, but no info on its strength. You need at least 3K cranking to jump the plug gap and light up a cold cylinder mixture. My gut tells me you are dealing with a fuel problem. Try some starting fluid into the intake to see if you get it to fire off.
 

Paul323

2018
CB650F
Feb 6, 2021
Riding Since
2019
So I got the engine running again, I followed the flooded engine procedure in the owners manual abs eventually got it going, now it starts no problem, my check engine light was on during my test ride but was off the next day when I took it to work so everything seems good now, thank you to everyone that gave advice
 

JAGDEN

2016
CB650F ABS
Feb 23, 2021
Riding Since
2020
So I got the engine running again, I followed the flooded engine procedure in the owners manual abs eventually got it going, now it starts no problem, my check engine light was on during my test ride but was off the next day when I took it to work so everything seems good now, thank you to everyone that gave advice
Hello Paul.

I have just installed a blinker relay for my bike, and in this case i have detached the Fuel tank. Now i got the same problem. My bike wont start, how didt you make the flooded engine procedure? Cant find anything in the owners manual.

Best regards JAGDEN
 
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