For those wishing to add an aftermarket exhaust or air filter, (or both), I wanted to provide an update on my efforts to dial in my AVL. Airflow to these engines in stock form is very restricted to meet the Euro emissions. Its been my experience thus far, that given the (relatively), large piston and long stroke, these engines yearn to breathe and the richer they run, the happier they seem to be.
The addition of the K&N filter and Dunstall muffler, without any jetting mods, revealed a bike that would barely run. My dealer was kind enough to make a house call and install a pilot jet one size up, a 120 main jet, (110 is stock), and move the needle setting one click down. For most motorcycles, this would be adequate. Not so the AVL, which showed little improvement in driveability, a high idle and an ash-grey spark plug, revealing a still lean condition.
The next step was to order three jets from our host, a 125, 127.5 and 130. The installation of the 125 was a noticable improvement, providing quicker throttle response and driveability, (I no longer have to crack the throttle every 10 seconds to maintain a given speed, it stays where you put it). After the test ride however, it still had a high idle, (no cracked or broken hoses and pulse valve hose is stell-braided), and the plug was ash-grey again - no dice. The AVL wants more still.
I bumped up to the 127.5 main last night after dark and haven't yet test drove. Each step up has been an improvement. Low-range torque has been phenominally improved and this motor has yet to be broken in so I ride it with kid gloves. All indications point to an impressive little torque monster at this point. Gas mileage be damned, I'm impressed with the power that can be released in these engines when you let them breathe.
I'll keep you posted.