Anyone know any classes where you cannot tune the bike?

Does anyone know of any classes where you cannot tune the bike, new suspention, or internals only, but no engine modifications?

I want to race, but I want to race people on similar machine, not be on a stock machine and many many others are on tuned up high bhp things i have no hope of catching.

A good rider on a slower bike will do well.
Racing is about bettering your own performance.
When you have pushed the bike to its limit consistantly only then is it time to consider more power.
Im not talking crap,Ive been there done that and got the T shirt.
Go out and enjoy the track,dont worry about being beaten but take satisfaction that you are riding up to your potential.

I have raced before, done quite good, think i was top stock bike, had about 10 sec gap to people behind me, and 10 sec gap to people ahead, and all ahead where tuned bikes getting about 20% more power.

hense why looking for a stock class where people done tune, then can have a fun race with others, not have to spend 5000 to be on equal ish machinery, to then be able to race others in the class.

Triumph Triple Challenge = sealed engine