About two days ago I noticed my 1993 CBR600F2 was running poorly (rough) off idle up to about 4K rpm's, then smoothed out. Almost sounds and feels like the engine is missing??? My first thought is to replace the spark plugs and see if that is all I need to do. I was also wondering if going to a hotter plug might help (go from the CR9EH-9 to the CR8EH-9 plugs). I keep running across the do's and dont's of changing the plug heat but wonder if it really makes that much of a diference???? I do tend to let my bikes warm up on choke for a few minutes before I ride off.....could this be fouling the plugs? Never had any problems before with the CBR and have owned it 2 years now....although I have not replaced the plugs since I bought it......Hhhmmm....Any input will be most appreciated. Hopefully someone has had a similar experience. Thanks. Feel free to throw in your 2 cents!!!

JP

 

Keep in the same heat range, just get a nice shiny new set of plugs, as for letting your bike warm up, I always do it & had no problems, I've done so with all my bikes. I've had some serious problems with some of them, but never engine failure. I let it idle for a good few minutes, pulling the clutch lever in to warm up the plates. Your bike may just need a tune, but try new plugs 1st

 

I've had this problem with an F2 and it's probably related to E-10 gasoline. The ethanol in E-10 gas can cause things that weren't affected by straight gas to disolve and collect in your carb jets. Since the primary jets are smaller than the secondary jets, they are more prone to clogging. It might take a while to clear up, but if you run several tanks with seafoam gas treatment, it should clear up. Either that or spend $300 to have your carbs overhauled. BTW, I have no affiliation with Seafoam, but I tried a bunch of other products, some cheaper, some more expensive, and Seafoam was the only one that resolved this issue for me.

Hope this helps...

JRM

 

sounds like the primary jets in your carbs are clogged..if the engine has no problems reving from 4k to redline then the smaller primary jets are clogged..pull the carbs, remove thesmall jets andtryto look through them..if you cant then clean the jets out with a strand of copper wire from a speaker cable..

 

I'd suggest the plug replacement first although if they were fouled you likely would have issues at all RPMs.

I would run a cleaner through the system as the others mentioned. However, I ran two cans of Seafoam through my system this summer and it did not help. I wound up running a small bottle of the Lucas Fuel System Treatment through (1 whole bottle in the tank for a super concentrated blend) then I ran a few plain tanks of gas and then one more bottle. It smoothed out after than and idles fine now at the factory RPM range. It's probably been 10-20 tanks since I did that and all is still well and it's been firing right up in the cold weather.