I have a 2008 1098 with 6,000 miles on what was a well tuned DP slip-on/ECU combo. I swapped the OEM style Termis for the new Termi (beveled) style and ever since my idle hasn't been the same. It was never I-4 smooth but since the change (nothing else was altered or adjusted) the idle, hovering around 1,450, would dip into the 950 range for an engine revolution or three before catching itself and jumping up to the normal 1,450 speed. The dip would happen every 10-15 seconds or so and made it sound like the bike was going to stall.

I hooked the bike to the VDST and set the TPS. The trimmer was set to 30 from the dealer. To test the fueling I decreased the trim to -25 (lean) which smoothened the idle at a low 1,150 or so and the bike would run for 10 seconds then stall. I could start it right up again, it would idle for about 10, then stall. Then I bumped the trim in the other direction. It is now set at +51 points and the idle shows a steady 1,350 as indicated on the dash (VDST shows it moving around, but about 100RPM on either side of 1,350), and there is no stalling. Occasionally the idle dip is apparent, but the bike is rideable where it was really tough before when RPMs were below 2K either at idle or moving slowly. There is a slight surge around 3,500 but above 4K is smooth.

Will a simple change from one set of Termis to the other require a bump in the trim of 21 points or did I just mask another issue?