T-120 First Mod

[atomsplitter]

Today I fitted a Motone X-Pipe Cat Delete to the Bonny. That was 4 hours I'll never get back. To get the cat box out you have to remove the left frame rail. The top frame rail bolt (8mm Allen Key) is behind the gas tank so you have to pull the tank back about 4 inches to expose it. There's no captured nut on it so to get a box end wrench on the backing nut you have to pull the radiator forward abot an inch. Very fiddly coming off, a nightmare going back on. I ended up pulling both exhaust headers off because the bracket the cat box bolts to is impossible to remove with the cat installed. With both exhaust pipes out I was able to wiggle the cat box enough to finally clear the bracket. The cat box weighs in over 4 lbs, the x-pipe about 770 grams. I had to transfer all the fittings off the cat box to the X-pipe to begin reassembly. With the X-pipe in place (another overly fiddly process) bolting the headers back up is a fiddlers delight. The retaining collars that compress the exhuast flange against the exhaust donut in the cylinder head are two piece. You have to hold the header in just the right place to get both bolt holes to line up through both halves. It's also advisable to reinstall the O2 sensor plugs before reinstalling this flange because you can't get a wrench into the tiny space between the fins and turn the sensor. After getting the right side all bolted up and secured it was time to reinstall the frame rail. I had to put the flange nut for the top bolt in a box end wrench, then carefully manuver the wrench between the top of the radiator, a few cables and wires, then gently turn it sideways to face the bolt threads without spilling the nut out of the wrench. What joy. Once all the frame bolts were inslalled I went ahead and torqued them down, reinstalled the radiator top bolt and proceeded to reinstall the left side exhaust pipes. Same epithet inducing trauma as the right side. After everything was put back, torqued to spec and the seat back on I rolled it off my lift and out into my drive for a test fire.

The engine fired right up with a much deeper, throatier note. I left it idling for about 5 minutes while I put the garage back in order (had to take the ramp off the lift, roll the Rocket in, move the XS11 back to the 3rd bay, park my pickup back in the garage, etc). I then took the bike around the block to see how it responded to the throttle. The difference was noticeable. The lag between throttle input and engine response was gone entirely. The motor snapped to when asked and acceleration was very crisp. I got a few decel pops but nothing bad. The ECM will eventually adapt fully to the mod and the decel pop should disappear. If not I can always remap the fueling to enrich the last 6% of throttle opening. I think this mod will be very useful over the miles I'll put on this ride. Next up, the suspension bits arriving Tuesday.