speedo intermittent on & off???

[mocko]

Hi guys i bought my 172cup two days ago private sale' and as ive noticed the speedo just drops down as if its lost its connection then after a couple of minutes just pops back up to whatever speed im doing? Any ideas guys ive txtd the last owner as i was annoyed to ask what is wrong with it but just as i thought no reply hope you can help on this guys cheers

 

[twilliams6854]

It'll be the speedo sensor. Fitted to the back of the gearbox.

http://www.k-tecracing.com/show_product.asp?id=4188&appid=2