Boxerworks.com

Hi, it's 368xx miles, but unknown how many were on unleaded fuel. After 20+, I don't remember the initial issue, but suspect it was the valve recession first causing trouble. Heads get sent out 7/30, not going to look any further until they return and I put some miles on it. The seat recession just ...

Hi, and THANKS for the reply. I'd been riding this several (`3) thousand miles, can't know about previous owner. Neither of us aware of valve seat consequence. So it might be a matter of deterioration of the seats. Stupid truth, get the heads upgraded to unleaded tolerant fuel and see what happens. ...

Hi, Much thanks to you both. The eroding seat makes total sense. That said erosion accelerates rapidly would explain my problem. Engine gets to temp, valves recede & not close, readjust simply lets it repeat. I'm thinking, pull & send out the heads. Then reassemble with a fresh gasket set. F...

Hi, new to forum, not BMWs. Bought a '74 R90S in '87. Had it worked on by someone who I thought knew more about machines than me - Big Error. Anyway, after this "service" The valve train developed a strange behavior: after ~5 miles it starts to sputter and backfire through the intakes. In ...