Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.
Posted: Fri Jan 02, 2015 3:26 pm
The JD kit should give instructions for the OEM exhaust. It's the triple taper needles that makes the difference. There are two needles-one for hot weather and one cold or high/low altitude if you look at it that way. They're about a half step apart overall. Do it you'll be satisfied with the great response over the entire rev range.
Exhausts on off road bikes aren't nearly as restrictive as street bikes. Especially the MX/SX racers. They rarely actually meet the noise restrictions when tested on the pre 2010 bikes. My '03 CRF has a custom made relatively open megaphone w/stock headpipe tuned for low-mid rpm grunt. It can climb serious hills from a dead stop at the base of the hill. And revs clean to 10K+. It's an awesome critter in the woods (flywheel weight/gearing too) but a bit boisterous when you turn up the loud switch. And the JD kit helped considerably with that tuning. I need to make a DB killer to tone 'er down a tad.
Exhausts on off road bikes aren't nearly as restrictive as street bikes. Especially the MX/SX racers. They rarely actually meet the noise restrictions when tested on the pre 2010 bikes. My '03 CRF has a custom made relatively open megaphone w/stock headpipe tuned for low-mid rpm grunt. It can climb serious hills from a dead stop at the base of the hill. And revs clean to 10K+. It's an awesome critter in the woods (flywheel weight/gearing too) but a bit boisterous when you turn up the loud switch. And the JD kit helped considerably with that tuning. I need to make a DB killer to tone 'er down a tad.