Running Rough?

Recently bought a 2002 CB500-2, it was serviced before I bought it, but I'm not happy that it's running right.

I've previously ridden a YBR 125 which ran very smoothly and was very forgiving if you were in too high a gear. Should I try and keep the revs above a certain level on the CB? The reason I ask is that there is loads of vibration at anything below about 4100 rpm.

I'm used to being able to ride comfortably at 30mph in 5th on the 125 but the CB isn't happy at that speed unless I'm in 3rd.

Don't want to spend on a garage if it's normal.

Sorry if I'm being a bit dim but I don't know what to expect.

Many thanks.

John

Rule of thumb for the CB, at 30mph, I'd probably be in 3rd, 40mph 4th, 50 5th 60+ 6th, and yes keep the revs over 4k for smooth running.

IMHO it tends to go better if you thrash it :)

As per previous comments, there isn't much below 3000rpm; the idle should be set at 1300, so it shouldn't take long to get above 3000....

Vibrations shouldn't be **really** bad, have you had the carbs balanced recently? This can cause rough running.

Do you know what the garage did when they serviced it before you bought it?

Do you know if the bike has been left standing for an extended amount of time? If it has then the carbs can get gummed up with petrol residues - this will not help the good operation of the machine.

This is my view of RPM vs Speed. It is approximate any any corrections are welcome


Ratio 3.46 2.23 1.75 1.48 1.28 1.13
1 2 3 4 5 6
1000 4.28 6.64 8.46 10 11.56 15.14
2000 8.55 13.27 16.91 20 23.13 30.29
3000 12.83 19.91 25.37 30 34.69 45.43
4000 17.11 26.55 33.83 40 46.25 60.58
5000 21.39 33.18 42.29 50 57.81 75.72
6000 25.66 39.82 50.74 60 69.38 90.86
7000 29.94 46.46 59.2 70 80.94 106.01
8000 34.22 53.09 67.66 80 92.5 121.15
9000 38.5 59.73 76.11 90 104.06
10000 42.77 66.37 84.57 100 115.63

Many thanks for the replies. AFAIK the bike only had a basic service before I got it.

The guidelines for speeds in each gear was really useful.

I'm going to take it to a local indie on Monday to have a quick look over, just to set my mind at rest and he'll check and balance the carbs if necessary.

Regards running rough, it might help to raise the idle speed. Turn the yellow screw hidden behind the engine block. If it was setup in the summer, now the weather hads dropped a few degrees it might not been ticking over quite high enough. Especially so if stored out doors, used for short journeys, not left to warm up before setting off.

Thanks for all the help/advice. Took it to the garage on Monday and he says it's all fine. Looks like it's just me not being used to it.

The revs/speed advice was particularly helpful and I'm adjusting my riding style to suit the bike.