BeemerShop Custom Sized BMW Motorcycle “Airhead” Exhaust Valve Seat
Sold individually, an order quantity of one gets you one valve seat. They are NOT sold in pairs.
One of the advantages of overhauling so many BMW heads for such a long time is that we had opportunities to see our work again years later to observe how our parts were holding up. Sometimes the heads would re-visit our shop for dual plug machining, or exhaust thread repair, or valve size changes due to changes in cylinder size to give a few examples. Since our valve seats are custom made, we’ve been through a few seat manufacturers, trying different seat alloys and eventually settling on a USA made product that has given us consistently high quality seats with very stable dimensions and excellent wear characteristics. These seats have withstood the test of time so you can be assured of their proper application and durability.
Please note; valve seats are sold in oversize because the seat pockets don’t stay round and need to be bored in a mill until the pocket is true and you achieve .008” interference fit before you install the new seat.
709365285 has an OD of 1.709” and fits R75 and R80 all years (38mm exhaust valve).
709420285 has an OD of 1.709” and fits R90 and R100/7 1977-1978 with 32mm carb (40mm exhaust valve but small OD seat).
800420285 has an od of 1.800” and fits R100 models with 40 mm carbs from 1977-1984 (40mm exhaust valve with large OD seat).
820420300 has an OD of 1.820” for badly distorted seat pockets that require extra machining.
In our experience it is rare that the R50/5 or R60/5/6/7 need to have their exhaust seats replaced, there never seems to be any valve seat recession with these low output models. We do stock them if needed however, call for pricing.
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