Damn Seat Bolts!!!!

You probably need to add some information on the year/make/model of bike to get this help. If you go to one of the online parts catalogs, you can look up the part and it will generally tell you the bolt sizes. For example, go to Bike Bandit, choose OEM Parts, then make, year, model. Once there, choose the Body and Fenders selection and you should find the Seat.
https://www.bikebandit.com/

 

Regular PITA aren’t they?!

M6 x 20 socket button headed

https://www.namrick.co.uk/acatalog/..._Head_Screws__Grade_10_9_Zinc_Plated__36.html

32p each plus p&p! I fit shake proof washers under mine.....

 

I am so glad the seat on the current model locks on with the key instead!

 

For Sir with the fuller figure an 8mm upgrade? Suits you Sir!

6mm for Snake Hips