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CBR650F Very Minor Throttle misfire issue (Occurs when commutting in the same RPM in 2nd or 3rd gears)

murali_db

2018
CBR650F ABS
Dec 28, 2018
Hello Everyone,

Last few days i faced a very minor issue, just want to know if any of you guys faced the same.

Issue : There is unnecessary revving in RPM, sometimes very mild increase, and revvs down suddenly once(slight revv down, probably 1k RPM) or twice in one short(20kms) regular commuting ride. I have adjusted the clutch play and Clutch Nut, thinking this might be due to clutch slip, but i have been wrong as this repeated even after the change.

Do you think this needs throttle cable to be checked for functioning and lubrication ? has any one faced the same ? Do i have to look anything else ?



P.S: Happens only when riding in constant same speeds , same gear and same RPM revv range for 4 to 5 minutes.


Thanks in advance
 

Brammers

2014
CBR650F ABS
Staff
May 30, 2014
Hampshire, England
This could be due to an intermittent short on the plug caps.

You don't mention water or rain, but is there any correlation with the engine getting wet?
 
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murali_db

2018
CBR650F ABS
Dec 28, 2018
This could be due to an intermittent short on the plug caps.

You don't mention water or rain, but is there any correlation with the engine getting wet?

Hi Brammers,

No not at all, even when i rode on a rainy day a month back it was perfectly fine. So there is no correlation with the engine getting wet.

One more question, what do you mean by intermittent short, can you explain it more verbosely please.
 

murali_db

2018
CBR650F ABS
Dec 28, 2018
There is a mild pull in the rear when I throttle up, very mildly slowing me down that a first time rider can’t identify.
 

miweber929

2014
CBR650F
650 Alumnus
Staff
Feb 13, 2015
Woodbury, MN
Riding Since
1975
I’d give it a tank or two more gas before doing much more troubleshooting. It sounds to me like it might be bad fuel.

Have you recently changed oil?

How many miles on the bike?

You’re sure it’s not better or worse since the clutch cable adjustment? Do you have any free play in the clutch lever?
 

murali_db

2018
CBR650F ABS
Dec 28, 2018
I’d give it a tank or two more gas before doing much more troubleshooting. It sounds to me like it might be bad fuel.

I had this issue initially when the Fuel was in reserve, later i filled up till 4 fuel lines in the fuel gauge and adjusted the clutch play. Felt minor issue later in throttle response and something pulling behind. However i did not feel much issues in my today's ride.

Have you recently changed oil?

Changed it before 50 days, when the bike was delivered to me, oil filter and oil was replaced.

How many miles on the bike?

2111kms on the odo till now, took delivery when it was 823Kms

You’re sure it’s not better or worse since the clutch cable adjustment? Do you have any free play in the clutch lever?

Clutch free play i have adjusted according to the manual, i dont think this is related to the clutch cable adjustment, however the shifting is smooth now.(Attached clutch free play image)
Clutchplay.JPG
 

miweber929

2014
CBR650F
650 Alumnus
Staff
Feb 13, 2015
Woodbury, MN
Riding Since
1975
Ok, thanks it that.

So it’s probably not oil or clutch related, you don’t have enough miles on the bike and the clutch seems to have some free play to it so we can, for now, rule that out.

If it acted up with a low fuel level, and got better with a fill up, I’d say you may have some water in the fuel tank or just some bad gas. You can deal with it by fully draining the tank and starting fresh, putting in a water displacing additive if you have that available or simply riding it as is as far as you possibly can then adding fresh fuel to dilute it as much as you can.

Run a few tanks of gas through, then see how it acts and report back to us here. We can move forward from there.
 

murali_db

2018
CBR650F ABS
Dec 28, 2018
Ok, thanks it that.

So it’s probably not oil or clutch related, you don’t have enough miles on the bike and the clutch seems to have some free play to it so we can, for now, rule that out.

If it acted up with a low fuel level, and got better with a fill up, I’d say you may have some water in the fuel tank or just some bad gas. You can deal with it by fully draining the tank and starting fresh, putting in a water displacing additive if you have that available or simply riding it as is as far as you possibly can then adding fresh fuel to dilute it as much as you can.

Run a few tanks of gas through, then see how it acts and report back to us here. We can move forward from there.


Hi,

Thank you very much on your suggestions, as i updated on last friday the issues i reported was not there on my last week thursday and Friday rides. Looks like your troubleshooting is 100% right : ) .

I took her to service on saturday, technician said those minor issues must be due to Fuel clogging as even small adulteration's in fuel matters it seems. I once filled 1 litre of gas in a very small petrol station as it was a emergency, i doubt that petrol station now, only after this incident i started facing these issues, first time issue occurred to me when i was in Reserve fuel .

Other thing was no throttle play at all, after setting it to 3mm the ride quality is far far better and reduced a lot of pressure from the palm, he also adviced me about the clutch play i adjusted, to adjust the Clutch nut in most cases and do only minor adjustments in the upper clutch cable adjuster (In my above screenshot i have the Clutch cable adjuster far more away from the lever).

All is well now, ride quality is awesome now. Thanks to everyone for your help.
 
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