Valve Adjustments

[pedrocasper]

Greetings: First! The next few sentences will underscore my ignorance of the Boxer engine....but, like all things in life, I hope to learn from my more experienced compadres. So here it goes.

I recently changed the oil and did a valve adjustment on my "new" 1984 R100 w/33k miles. I am comfortable in my knowledge in testing and adjusting valves since I have done it on other bikes and cars. I even torqued the heads to the correct NM as described in my Haynes manual.

However, upon taking the bike out for a ride I heard some valve “ticking”. Both sides sang out the same “ticking” tune….so I either screwed up my adjustment equally on both sides, or the ‘ticking’ is normal. Any thoughts? Note, I expect even my assumptions could be incorrect.

[jmerlino]

Tappy valves are happy valves (or so I've been told).

[BubbaZanetti]

yep, mine got louder for a time whenever i adjusted them


i'm sure you found your exhaust had closed up a bit, but your intake was fairly dead on.......its the space you put back in the exhaust valves causing the tapping...........

[lkchris]

Ticking is normal.

Wear earplugs.

[20774]

What was the torque setting for the heads? And you got it from Haynes?? Life on the dangerous side ;-). I think the number is 26 ft-lbs for the head bolts...I tend to error on the low side, maybe 24-25 and call it good. I've heard of errors in Haynes, Clymer, even BMW manuals with conversion from NM to ft-lbs...best to compare several and get a consensus.

Kurt in S.A.

[pmdave]

The torque specs I have call for 35 to 39 Newton-Meters. The conversion to foot pounds is x 0.73756. My calculator says the specs should convert to 25.8 to 28.8 ft lb, assuming clean dry threads. I crack each nut about 180 degrees to break it loose, then torque. I also use a cross pattern, and if I find more than one loose nut, I torque in stages.

If those exhaust valves aren't ticking, they are burning. Ticking valves = good; quiet valves = bad. The original specs were .004 in and .004 ex, but later the specs were revised to .006 in and .008 ex.

The R100 motors had a tendency to burn/melt/wear exhaust valves. One of my kahunas felt this was due to the reduced mass of the cylinder head in comparison to the cylinder volume. Boring bigger holes in the same casting means less metal to carry away heat.

Over the years BMW tried various different combinations of valve and seat materials, and different valve seat angles. The specs they arrived at around 1986 seem to work, and late valves and seats can be retrofitted to older models. The 750cc and 800cc engines didn't seem to have the same problem.

With the original valves/seats/guides, my 1980 R100 could go through .006 exhaust valve clearance in 500 miles if run WFO pulling a sidecar over the mountains. I would adjust the valves on the road whenever they got quiet, sometimes every other day. The symptoms of tight valves are the engine quiet, and not wanting to idle (stalling) after a long, hot run.

pmdave

[Pierce]

It could also be rocker arm side play. There is no spec for the rocker arm clerances between the rockers and the head bolts(ends of rocker shafts). But I'm told by a seasoned independent BMW mechanic, to get them as tight as you can and still have free movement. I know it doesn't seem like much, but if there is enough play they can make noise. Pierce BTW, I just got through doing the same thing to my bike yesterday.

[Boxerkuh]

Always good practice... first looses the head bolts by 180 degree's, then torque them to specs.... Then adjust your valves... Do that every 2,500 miles and the airhead will run forever. As long as you hear the ticking you are okay... When it stops ticking it is time to adjust them again, because they tightened up... Recognize the sound and listen for it... as long as they are ticking you are going good! :dance Worry it you don't hear it. :doh

[20774]

My experience is that the head torque stays pretty much where it should for many miles. If it isn't then something else is going on, especially if you're many miles past a top end job. Personally, I'm a little reluctant to loosen and retorque the heads that often. IMO, you invite the possibility of pulling out a stud. I'd recommend just checking the torque, especially if you have a clicker wrench. Set the wrench for the 24 ft-lbs range and see if it clicks without any movement. If she clicks off, I'd say you're good to go. YMMV...

Kurt in S.A.

[lkchris]

It could also be rocker arm side play.

Not really adjustable on an '84.

[cjack]

Not really adjustable on an '84.

I think BMW suggests using thin shims there. Measure for something like .05 or so mm maximum. BMW parts supplies shims in the thicknesses of .25 to .50mm, one every .05mm for this purpose.

[Pierce]

Not really adjustable on an '84.
Well, yes and no. Technically no they are not, but a technique I use is to use a large c-clamp with sockets large enough to slip over the outside of the rocker arm shafts, placed on either end. Apply a little pressure with the c-clamp, essentially squeezing the ends of the rocker assembly enough so that there is little to no gap between the rocker and the block that the head bolt goes through yet still alowing free movement of the rockers. BTW, do this with the head bolts "loose". Then retorque the head. You can over do this so that there is no free play side to side and the rockers is hard to move. We certainly don't want to do that. The rockers on my 81 R100RT has some shims on the rockers to take care of the side play. Certainly some of you more seasoned airhead riders have heard of this technique haven't you?

[cjack]

Well, yes and no. Technically no they are not, but a technique I use is to use a large c-clamp with sockets large enough to slip over the outside of the rocker arm shafts, placed on either end. Apply a little pressure with the c-clamp, essentially squeezing the ends of the rocker assembly enough so that there is little to no gap between the rocker and the block that the head bolt goes through yet still alowing free movement of the rockers. BTW, do this with the head bolts "loose". Then retorque the head. You can over do this so that there is no free play side to side and the rockers is hard to move. We certainly don't want to do that. The rockers on my 81 R100RT has some shims on the rockers to take care of the side play. Certainly some of you more seasoned airhead riders have heard of this technique haven't you?

That's the way we did it...but it seemed that the blocks would want to slide back to where they were when they were tightened or maybe after the engine ran. In the very early /5 I think they had wavy washers. Then in the mid seventies, I think they had nothing and then when the needle rockers came out, they had the shims. If I had any of the earlier systems, I would buy the kit for the needle rockers if it's still available or make it up and use the shims. The kit used to cost around $375 list for all four rocker assemblies.

[The_Veg]

Or to put the answer to the original question a different way, it's better to hear them than to smell them.

[Boxerkuh]

Or to put the answer to the original question a different way, it's better to hear them than to smell them.

There you go... can't be better said!! :stick :bottle :bikes