I have a 2006 YZ250 that I got in 07. I ride lots of hard, tight and rocky single and 2 track. My bike has never overheated or boiled over before until now. I installed a Rekluse EXP 2.0 about 7 months ago. About 7 rides or so ago I was going up a long steep slick switch backed rocky hill and when I got to the top steam was coming out of my overflow. Let the bike cool down and then I put about 8 oz. of water to fill it up. I rode the rest of the day and had no problems. I pressure tested the cooling system and seen the water pump licking out of the weep hole. So I put in a new shaft (it had a grove in it) 2 new seals and a new bearing. Rode the bike for several more weekends and bike was fine. Then last Saturday the bike boiled over 2 more times again up 2 nasty hills. I needed to do a top end anyway so I took the head off and found a bad inner O-ring and my piston was very clean so I know I was burning coolant. I spoke to Rekluse and he said the EXP can make the bike run hot but it should not overheat the bike. So maybe the O-ring was slowly going. I am thinking of putting on a higher pressure radiator cap. Stock is 1.1 BAR (16 PSI). I could get a CV4 20 PSI or 30 PSI or a Tuck 1.6 BAR (23 PSI). Witch one would be safe to use or is it a bad idea to go higher than the stock 1.1 BAR?