Just found an '85 R80RT ... I guess I'm old enough to appreciate them now. Anyway, my question is ... was the head alloy problems of the 81 to 84 airheads (valve seats?) solved by '85? Not that it's an issue now ... cause I've already got it.
The updated seats were installed beginning in 1986. R80s had less trouble than R100s in this regard, so I wouldn't worry.
Alloy problem? The problem was/is the valves and seats. Some people had major problems with Valve recession, while others did not. I think that the majority did not have major issues. Myself included. My 1981 R100RT has "those heads". It presently has over 365,000 miles on the original valves. Still no problems. I have had this bike since new and have ridden the heck out of it, 2 up touring, 1 up back road carving and commuting 120 miles a day almost year around for over 12 years. I have had numerous airheads of that era. Only had problems on a couple that were abused before I got them. Did a valve job on them and had no further issues. Basically, my recomendation is to not worry about the valve issues that people go on about. You have purchased an old vehicle that will need at least a little work. As all engines get higher milage on them, expect to have to do a valve job eventually. Big deal. Not really. Get it done and get on with riding the heck out of it. That is what they were built for.
If you want to go into details ... there is THAT. Thanks for the input ... This one only has 20K on the clock. I think I'll be fine
I don't know anything about all this motorcycle nonsense but that sure is a cool Coke machine P.S. 74,000 miles on my '85 heads and they're still making the same God-awful noise they always have
Seats were too hard for a lot of the valves, and valves would erode to a razor's edge w/in 30K. The intakes seem to manage fine, but the exhausts will need new valves and guides fairly frequently. Seats can be reground until they start to pocket the valve, then should be replaced. Changing out the seats is best left to a jobber well versed in BMW twins. I've seen replacement seats drop out of the head pretty frequently, and often with disastrous results.
MAN DB, it sure is rare to hear the other and real side of the '81-'84 valve recession issue here on the idiotnet. I am not saying that those years don't have more than their fair share of valve recession but MANY go MANY a mile with no problems whatsoever. I have seen about every airhead model made have valve recession! They all do it to some degree.
I have seen many a '81-'84 head take way longer than 30k miles to start valve recession. Of, course, I have seen a Mcmillion more than that never start it at all but . . . . In my experience, you never know whether or not it is going to be the seat giving way most or the valves and that includes all the other model years that I have seen valve recession in as well. And then there is about a third of the time when they both have given way evenly. If the valve has tuliped very bad at all, I would replace the seat even by odd chance that is still looks salvageable. Chances are when you pull that same seat you can see plain evidence of exhaust gas getting under the seat and that is a sure sigh of compromised heat transfer from the seat to the head and that is a problem if not sometimes THE problem. I agree that the recession issue never included the intakes. That awesome stock cast iron intake seat will last almost forever IF no one cut's/grinds deeper than just kissing them. They almost never need anything more! It's a shame to see them replaced with something half as good or ground down to nothing for no good reason. I also agree that replacing seats is best left to someone GOOD at it. I would say that 9 out of 10 seats I have seen come out were just put in there not that long before!
Actually found two ... I won't even tell you how much I paid for both of them. The other *might* be of interest to you ... '74 R90. http://www.facebook.com/album.php?aid=89355&id=1024893379
Because the issue is inconsistent across the year range; I have to wonder if BMW was using more than one vendor for valve components during the period. I've noted that the large valve models (RS etc..) are more likely to have exhaust valve issues, while low compression models (G/S etc...) generally do not. Even with exhaust valve issues, 100K with only minor interventions is still a reasonable expectation. These are old bikes. Probably a lot of other variables to consider; Owner maintenance intervals, driving style, fuel selection, lubricant choice, etc... I'd echo the advice not to worry about it too much.
I have always gone by the concept that if oil consumption is low to none and you have good compression, gas mileage and performance, then leave it alone and ride it. Check you valve clearances regularly, change your oil and filter often, use quality oils and fuel. Don't go looking for a problem that may not be there, because you just might create one worse than you started with. If any of the above starts to change, then check things out. Oh, and it does look like you have a tranny issue with that bike. But it will probably just polish right out with a little elbow grease.
I feel the same way about the '74 model year. Ahem! (Got a tac, seat, and Krauser rack (and/or bags) you want to get rid of?)
I think BMW uses more than one vendor when they can for a variety of reasons. I think the issue is mostly due to metallurgy that about any vendor could suffer. I have seen many a different brand suffer the same problem. Here in the states, the most effected models are low compression. I tend to think that the problem is independent of CR but I have seen more issues with lower compression models than higher compression models myself. Typically speaking, higher compression lowers exhaust temps. Diesel engines are a perfect example of that phenomenon. That's my thinking anyway.
