I finally got around to modding my carb. I've had the jetset from Lancer and an extra white space for over a month. I ground the spacer to 1/2 the thickness. I replaced the main jet with a 150. I went to adjust the pilot air screw but it looks like the screw was pre-boogered-up by the previous owner. I only ever heard it backfire after going uphill riding 2up. Maybe the rejet and spacer will fix that. It runs quite a bit smoother now. It doesn't surge at 65mph any more. I can shift 5-7mph sooner without feeling like I'm lugging it. I am a happy camper. WooHoo!