Jake,

Here in Ireland it is only within the last 25 years that the senior class was classified 351 - 500 cc, this was done to prevent the quick oriental 350's from beating the established 500's. There were many riders in past years who could not afford more than one machine and it helped financially to enter the 350 machine in the 500 class.

Some years ago a competitor was disqualified for using either a brand of petrol or a brand of oil which was not declared on his entry form