At all the MX meetings I have gone to the bikes get washed and prepped between heats, I would like to know if this is really a necessity. Okes race an off road race for 6 hrs in the thick dust and the bike is fine so why wash and prep bikes after only 15 mins of racing - Am I missing something ??
Definitely makes a difference. Weight as Bull mentioned. When I raced track I fitted a newly prepped air filter for each heat. The dust is bad. In track literally each hp and second counts.
Enduro you obviously dont have the luxury.
But in the national off road events we used to fit newly prepped filter, clean chain and re lube etc in the de control section. If there are washing facilities we used to wash. Only race I recall though having it was TDR1000.
It feels really good to get on a clean bike, helmet, gloves goggles and whatever else you have for the second half of a race.