Allowed modifications

I am trying to understand the rules. The organizations that cover my area are AKRA and Dart. For the laydown enduro stuff how much engine modifications are allowed in classes like Yamaha pipe or A limited when running a KT100 or KA100 (reed). I’m talking about different carbs, porting, compression, custom pipe dimensions etc? Obviously the class description covers stuff like fuel type, pipe or not, maybe stock carb but if not mentioned can the internals, carbs, pipes be changed? Thank you for the help.

Yamaha pipe engines meet the same rules as they do in all other series. Ports are stock, minimum head volume, spec carb and approved pipe (there are several).
I may have missed it but I don’t believe that AKRA and/or DART offer an A Limited class. KART does. I’ve also not personally witnessed a KA100 in use in any class in road racing.

Thank you Rapid. You’re right AKRA does not show an A Limited class. Dart says they use AKRA rules and Dart classes shows A Limited. Weird, or I’m even further off.

So how do you know when the motors can be modified and not just spec. Does the word “controlled” offer a clue when it is in the class name. Or is it all just based on experience?

When the class group allows “stock appearing” does that mean the insides can be modded but stock pipes and carbs?

Controlled is a “controlled stock” class.100cc reed valve engine Ports must match a strict port diagram, head volume is spec as are carbs, runs gas and oil.
Stock Appearing is just that, engines must be stock appearing, typically 100cc reed, gas and oil, spec carb but porting and compression is open.

Thanks you!:grinning: