Originally Posted by
FMS88
The BVV part in your pictures is an electromagnet. When energized it pulls on the metal disk of the BVV diaphragm. At the other end of the diaphragm shaft is a donut shaped disc. The shaft goes through the center of the disc. To access and remove the diaphragm and disc, the top, air horn portion of the carb must be separated from the phenolic mixing body. Chances are the disc has degraded so the float bowl is always exposed to atmospheric pressure and that’s causing the rich condition. Before you remove the disc, note the direction of the slightly tapered end. Fortunately the disc and diaphragm are inexpensive and available on eBay so consider replacing them even if they look okay.
Good luck with Douglas. Hope it doesn’t case you any problems.
Bookmarks