(Read "Dumping the Gizmo" here first or this wouldn't make much sense)
Plugging the pipe from the inlet made the CBF run better, but not perfectly. There was still a slight stutter on occasions.
My plan was to dump the air injection control valve and install pipes from the breathers on the cam cover & gearbox. This, as it turns out, would have been a bad idea. I bought some 12mm fuel pipe to use as breathers but while on eBay I bought an air injection control valve for £13 (Honda price - £104) This could be fitted if the breather idea didn't work.
When the parts came I decided to put things back as they were with the replacement valve. The bike ran fine. Out of interest I checked how much air came from the control valve to the air box. I was surprised to find suction. The valve injects air from the air filter into the engine. Air is in turn pumped out of the engine from the gearbox breather. Installing a breather from the cam cover would have meant that dirty air would be sucked into the engine. The line to the inlet is a vacuum switch that closes the valve at high vacuum (ie when the throttle is closed)
|Air circulates likes this|