Lazy Tachometer Response
Posted: Thu Mar 27, 2003 4:07 pm
I just purchased a 79 CBX with about 10,000 miles (16,000 km) on it. The bike seems to be in great condition with only one obvious problem. The tachometer is very unresponsive and inaccurate. The tach needle cannot keep up with engine revs as engine speed increases or decreases. I have checked and lubricated the cable and tach drive but the problem is no better. Is there any way to repair the instrument or must it be replaced? Any help from you gracious experts would certainly be appreciated.
Oils in the mechanism dry and harden with time and produce these characteristics. 
Had to replace the speedo on my 79 two years ago, because of the same illness. Sometimes, heating the instrument up carefully (in an oven) to try to melt the stuff out has supposedly worked. Although, I personally would not encourage it.