Forum bmwbike.com

Dear Mark and fellow riders,

Has anybody tried fitting valve stem seals to R60/2 and if yes where can you get them and what is involved?

My heads are ready for a christmas present and it might be a good time to do it during complete overhall.

Last question, do you have to change valve stem guides (only valves and seats) by goinng to unleaded fuel?

Thanx a lot and cheers

Tom Bohacik

If you are going to do valve work, it is most efficient to do everything that needs to be done at the same time. And I think all work should be done by a professional who is experienced in /2 head work. The only thing the average owner might be able to do, if the valves and seats were OK, is to lap the valves to their seats.

It takes a pro to inspect the heads and determine what they need. And it they need work, it takes a pro to install guides (seals) and seats, as there is precise measuring and machining required. And even a pro can do poor work if not given a good budget to work with, as was the case of my R60/2 whose heads were first reconditioned for the previous owner by Matthias Dobler in California. Story at:
http://home.insightbb.com/~aatherton/R60-2/R60-2.html

The problem with unleaded gas is that it can erode old valve seats, causing them to wear away (recess). This destroys the tight fit of valve to seat, and results in constant valve adjusting . The seats soon need to be re-ground to fit the valve, which reduces the amount of seat metal and eventually the seat may fall out and damage the cylinder.

The good news is that unleaded gas almost never hurts our old /2 seats unless the bike is ridden very fast for long periods of time. The main problems with unleaded gas occured in the early 1980s, on new R-bikes. If your valves and seats are good, I would recommend not doing anything except checking the valve adjustment more often, maybe every 1000 miles. If the valves continually require adjustment, that could indicate that the unleaded gas is affecting the seats.

I had the heads of my R27 and R60/2 completely reconditioned for unleaded gas by Bobs BMW in Maryland, and it is expensive. For my R69US, I had a local expert replace the valves and guides, but I retained the old seats which were good.

Retrofitting valve seals to the bike would require machining a groove in a custom guide that is long enough to clear the retainers...plus finding a seal that will fit....an expensive and time consuming job to achieve a result that is not required. These motors do not need valve seals as long as the valve to guide clearance is correct.

I forgot to mention the question on unleaded valve stem guides. The answer is that you do not need to get new valve guides for unleaded fuel...seats, maybe, but not guides. Your question may be related to seat replacement. The conventional wisdom is that since modern unleaded fuel omits the lead lubricant that kept the old seats from wearing too fast, that you need new seats for unleaded fuel. This has not be proven to me. Many /2's are out there with the original seats on unleaded fuel with no problem. I would have to guess that a major reason is that not many folks are putting serious miles on them any more. The more you run the motor, the more the seats will wear. If I was rebuilding the head anyway, I would replace the seats. If all was working okay, I would leave them alone unless the valve adjustment was changing too fast...needing tightening sooner than about 6,000-8,000 miles.