The air box is secured to the top of the transmission. Inside are components for the crankcase rebreather system and for the Pulse Air System which is a passive system designed to reduce emissions to meet the US standards in the early to mid-1980’s.
Air Box With Pulse Air And Crankcase Rebreather Components-And Some Leaves
NOTE: The picture was taken when I first saw the bike and the air box cover was missing. Leaves are not part of the crankcase rebreather or pulse air system inside the air box. 🙂
The Pulse Air System is a passive system with no active motors or moving parts. It sucks filtered air into the exhaust manifold in the heads to help burn any gasoline and to ensure CO emissions are converted to CO2. That said, according to Bob Fleischer’s information on the Pulse Air system, this increases the exhaust gas temperature and likely exacerbates wear of the valves and seats and could contribute to warped heads. The original valves and seats in 1983 had problems with valve recession due to excessive wear from the metallurgy BMW used to try and compensate for unleaded fuel.
For these reasons, I’m going to update the Pulse Air system and modify the air box so the valve train stays nice and cool. I will purchase a smog kit from Rubber Chicken Racing Garage that has all the parts needed to complete this upgrade.
Here is the documentation of how I do this work and a short YouTube video summarizing the procedure.
After I removed the wheels and the handlebar, I’m ready to remove the front suspension: the front forks, the steering stem nut, top plate, steering head bearings pre-load adjuster nut and the steering stem with the attached lower triple clamp.
Bike After Wheels Removed And Ready To Remove The Front Suspension