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[wkohn]

Originally Posted by cts1950

I have been watching this forum because I have a dtt II and have been using it for several years. I have recently upgraded my engine from 95 to 103. I have been ironing out the bugs and getting it's ride-ability improved. I was only getting about 35 mpg at first but I have been working on the air fuel maps to lean out the cruse range to 14.5-1 I am now getting 40 mpg in mountain riding better on the highway. One of my biggest problems was my home made true dual conversion similar to the fullsack. I could not seal up the rear pipe joint above the starter and had a minor exhaust leak. It seems that a minor leak is a major problem for a closed loop system. I was always ending up with extreme blm issues. I bought a set of v&h true dual headers and replaced just the rear header and it made quite a difference when I apply the blms I now get almost all 100s I could not get that before. I also had quite a bit of popcorn on decill the new header helped. I have been thinking about the 2 into 1 exhaust makes more power but is not friendly with the dtt system. I came to the conclusion with the large mufflers that I have the s&s ovals I did not have enough back pressure for the mufflers to work properly (over scavenging) and i made a new set of baffles to try to get rid of the sharp rap that I was getting and to increase the back pressure. I started with 2.125 exhaust pipe and cut 7 lengths of 1/2 emt tube. I also cut them all different lengths so their resonant frequency would be different. The long tube in the center of six outer tubes I cut to 16" each other is 2" shorter than the one before 16 14 12 10 etc. these I pressed into the 2.125 pipe. It has a Gatling gun look to it. This seemed to soften the rap and almost eliminated the pop corn. I think this helped with a reversion issue. I also noticed that the motor pulled harder at higher throttle settings. I have not had a chance to get it re-dynoed for a real look. My original numbers before all of the above changes were 105 torque 99 hp SAE. The torque was flat 2500 to 5300. My build is a se (jims) stoker crank, flat top forged pistons, ported heads , black diamond valves, woods bee hive springs, 85 cc chambers 10.1 cr ,compression releases, se 50 mm throttle body, woods 6hg cams, fueling super pump, delkron cam plate, and tp rocker boxes and roller rockers. 1999 base motor and ultra rewired with 2007 harness and instruments and hk radio.

Sounds like have gotten your AFR and Advanced Curve to where I want mine to be. I have a lower lift cam (HQ-0034G), 9.9 to 1 compression, 95", Gerolamy TB, B&E True Dual, K&N filter, and about 38mpg now. At one time I was getting about 47mpg on the highway. Wish I could get that again. Curtis has helped me in fixing some of the starting and drive issues. But now I need to get the mileage back up and keep the sparkknock away at the same time.