Hi, my bike is a CBR 600 F3 made in 1996 with 53k km (33k miles) on the clock. I bought it a year ago, but only now I had a chance to take it on a first longer ride. It was 3h half on the motorway at 130kmh (80mph) and half in the twisties. During the ride I noticed quite a bit of vibration mostly felt in the footpegs around 7-8k rpm (regardless of road speed, clutch position etc - definitely engine related). Other than that it runs great.

Since I bought the bike I cleaned the carbs, I replaced float valves as they were sticking and the petcock as it was letting the fuel through on off setting.

I was wondering what is the best way to quantify the amount of vibration and I tried various smartphone apps to measure it. Frequency fits the rpms, but the amount measured was all over the place (from 10m/s2 to 25m/s2). I imagine a smartphone accelerometer held to a footpeg by hand is not the most repeatable way to measure vibration.

So I decided to put a cup of water on the tank and record a video of it in hope someone with another F3 could repeat it to compare if what I have is normal or not.

I've put the video here
https://youtube.com/shorts/JPw4KEa-Y8g?feature=share

The rattling that can be heard near 7k rpm is the cup bouncing on the tank from the vibration. It is as if the frame was becoming resonant at that rpm.

Could someone please record a similar one with their known good F3? (or view it and offer their opinion).

 

Check your engine mounts and make sure they are all snug. Maybe you have a worn plug and it’s crapping out at a higher RPM. The other possibility could be the carb isn’t synced. Did you sync the carb after cleaning it?

 

​​I checked engine mounts today. I couldn't get the torque wrench socket to check front mounts due to exhaust being in the way, but I used a spanner and an extension pipe to check by hand. Mounts appear fine.

BTW, did you see the video? Can you confirm what I have is excessive?

Can you feel any vibration in your F3 near 7-8k rpm? If you're not sure can you put the bike on the center stand (on pavement). Get the engine hot and put any object on the fuel cap on top of the tank. Then rev it slowly from 5 to 10k rpm and see if the object rattles a bit around 7-8k. It is not a huge rattle. I never noticed it before until I rode for hours in this rpm range.

The main point of me posting here is to find out if this is normal or not.

I cleaned the carbs without disconnecting them from each other. I pulled all the bowls, unscrewed jets and used carb cleaner and compressed air in passages. I didn't think there was a need to sync them after as I didn't touch throttle links. Plugs were supposedly new when I bought it 3k km ago. I'll swap them first if this vibration is definitely excessive.

 

I swapped plugs just in case, but I can't tell any difference. Old plugs looked almost new (0.85mm gap) and normal color.

I also got carbtune 2 meter so I'll do the carb sync when I have some time.