Ekki91

Hi, I recently bought a 'Big One' complete exhaust and fitted it to my 2003 DT 125 with no problem at all. The bike runs like a dream; in gears 1-5 the RPM freely runs up to 9-10k, with the powervalve kicking in at 8500 rpm. However! If I'm in fifth gear and kick up to sixth I lose RPM instantly and the bike bogs down to 55-60mph, with the RPM sitting at 7000. For example: Fifth gear = 70mph & 10,000 rpm no problem As soon as I kick up to sixth gear = RPM goes down to 7000 rpm and regardless of the amount of throttle, the bike reclines down to 55-60mph. If I put it into sixth at 45mph (before the exhaust swap it still had some acceleration at 40-45) it doesnt even climb speed, it just sits at 45. I was told to up the jets one size but I thought I'd ask people who know what they're doing! Thanks in advance ## EDIT ## Also, although the seal is tight and it's not blowing, it sounds like the exhaust is blowing where its fitted to the engine, at high speeds/rpm there's a very loud vibrating noise which sounds like a very loud rattling/vibrating/blowing... whats that all about?