Some bad news. From looking at the exhaust valves through the spark plug holes while shining a light in the exhaust port, it looks like valve and valve seat replacement needs to be done sometime soon. The edge of the exhaust valve goes to a sharpish edge. Normally, there would be a slim vertical surface between the valve cut seating surface and the valve face. The edge isn't "tuliped" yet but it's on its way. I may try to get through the summer and tear it down this fall but, definitely, no long trips until I can get the heads worked on. I've read that there are only a handfull of decent shops that know what they are doing with these old bikes. Time to start saving my pennies. This is a known problem with early '80s BMW airheads especially the 1000cc models. The valve seat material was replaced with a harder material to compensate for unleaded gas but they don't conduct heat as well. The exhaust valves overheat and slowly deform. I've read that rebuilding the heads are about $600. (Ouch) I guess I'll pull the heads tomorrow and give Porter's Beemershop a call.
Tuesday Afternoon - The recommendation from the Beemershop is that I may be able to get another summer season out of the valves since I don't really put on a lot of miles but check the valve clearance often. When the clearance starts to change rapidly, then time to pull the heads and send them off for rebuilding. The actual turn around for the rebuild could be in as little as 3 weeks but since their machinist is out, they're falling behind. I did order a new exhaust crossover to replace the one with the broken clamp since they're prices are way better than other online shops and I'll start reassembly once all the parts come back in.
Today ia another wonderful, warm day with great visibility. I had meetings for most of the day but at least I had to walk between upper and lower campus to make them all.
Richard:
ReplyDeleteHope you get this sorted out before the riding season, or at least the decision to ride and repair next winter or to do it now. Or perhaps there is a new F650GS with your name on it, with the vintage bike for sunny days. Never hurts to have a spare bike laying around
bob
bobskoot: wet coast scootin
Thank you for visiting.
ReplyDeleteI think I can get another season of riding and do the valve work next fall/winter. As soon as my order of small parts gets here, I can start getting things back together well in time for the riding season. I don't think a new bike is in the cards. I still am enjoying the old one. Being able to do much of the maintenance and repairs and the simplicity is an attractive feature of these old airheads.