CB650F Erratic/Rough Idle

[bfoster80]

Don’t know if you can hear it in the video, but it almost sounds like a miss? Goes away when I give it any amount of gas. Does it cold or hot. Any ideas?

 

[Rafe]

Have you done anything to the bike recently? Any upgrades or routine maintenance?

 

[bfoster80]

Changed the oil, nothing else. Seems to be getting progressively worse too. And I am also noticing a hiccup sometimes when starting off and a bog at low rpm's under load.

 

[bfoster80]

Bike had 800 miles on it when I got it a couple of weeks ago, now has 1500.

 

[baugustine]

did you fill up the fuel tank at a new location (ie bad gas)?

 

[bfoster80]

Nope, been doing this for a few tanks of gas. Even tried seafoam.

 

[ducatiman]

Bike had 800 miles on it when I got it a couple of weeks ago, now has 1500.

been occurring since your purchase at 800 mile? If not, at what miles and length of time into your purchase?

(I'm thinking the PO was under the tank screwin about, dislodged, displaced something)

 

[bfoster80]

Honestly, I did not notice it at 800 miles, but I was so excited at that stage I might not have noticed it, lol. I think it had the occasional hiccup when idling, just feel like its getting worse. I am running 93 octane fuel, could that be it? I think I am going to take the tank off this weekend and look at the filter/air box.

 

[baugustine]

drain the tank and inspect the bottom for sediment, water, etc.

 

[miweber929]

Honestly, I did not notice it at 800 miles, but I was so excited at that stage I might not have noticed it, lol. I think it had the occasional hiccup when idling, just feel like its getting worse. I am running 93 octane fuel, could that be it? I think I am going to take the tank off this weekend and look at the filter/air box.

With that low mileage, we need to figure out what's going on and it should hopefully be fairly straight forward.

drain the tank and inspect the bottom for sediment, water, etc.

So, yeah, I'd say start there. If your bike has been sitting and has bad fuel in it it may just be getting diluted. I would also agree the airbox and air filter are good places but also look at plugs, plug wires, any sensors you see, anything else maintenance wise you can look at.

So it does not change at all with engine temp? I'm thinking fuel issue. No reason to run 93 on this bike, BTW so fresh 87 is just fine.

 

[bfoster80]

Thanks guys. I really appreciate the help.
But it runs funky during the high idle warm up, but never changes no matter how hot it is. I am thinking some type of fuel maybe air issue because I have the occasional hiccup when taking off if I do not rev the engine up and the occasional jerking/bog in high gears under acceleration from low rpm.

 

[bfoster80]

So as an update, I took the air box off and drained the tank this weekend. Everything looked like a bike with 1600 miles on it. Like new. I took the Intake Air Control motor and valves out and cleaned them, but no luck. But, I think it defiantly gets worse when the engine is hotter. I ordered a new IAC motor just to try. Could it be a bad spark plug? It runs fine at rpm from what I can tell.

 

[bfoster80]

Well finally got it fixed, I hope. LOL. I knew it was something simple since the bike has less than 2k miles on it. But it turned out to be a bad spark plug!!! Friday night I replaced the IAC valve/motor and that did not fix the issue. I was pretty stumped.
So I decided to grab my heat gun and check each exhaust pipe while it was running, the far right/passenger side cylinder was reading about 50 degrees cooler than the others (130-140 compared to 190). So I went to the local auto parts store, picked up 4 new NGK plugs and replaced them tonight. Man she runs sooooo much better now. What is really strange is the plug did not look bad in comparison to the others, but I dunno. It works great so far. Thanks for everyones help.

 

[skeletor]

good job!