Valve spring height

[jimcarr]

Does anyone know the installed valve spring height for a 83 R100RS? My books do not give this information. Thanks.

[robtg]

36.6mm or 1.440"

[ME 109]

An interesting question, that makes me wonder the reason for the question?
The spring length would be dictated by the valve stem length and position of retainer
grooves?

Watchew upto Jim?

[robtg]

When valves, and seats are ground or replaced, spring height changes. Also, casting variations will cause differences in height. Shimming the springs is the normal fix.

[jimcarr]

Thanks!!! I had to cut the valve seats and the ex were worse off than I thought. I will have to replace them in a couple years. The factory book and my Clymer book only give free length. I think the installed length is more important.

[ME 109]

Ah-ha. So the adjustment of the rocker arms is not considered sufficient?
Is that due to the push rods fouling the tubes?
I haven't heard of shimming airhead valve springs. Not that that means anything.

[Rob Frankham]

FWIW,

If the exgaust valves have recessed sufficiently to have any real difference to the spring tension... which is what we are concerned about, right?.. then it is way past time the seats were replaced.

Rob

[vanzen]

FWIW:

The BMW manual valve spring specs 1981 –
Wire thickness mm (in.): 4.25 (0.67)
External coil diameter mm (in): 31.9 (1.256)
Relaxed spring length mm (in.): app. 43.5 (1.713)
Spring force in kp (lb.f) at test length mm (in.): 29 (63.9) at 37.6 (1.480), 70 (154.3) at 28.5 (1.122)
Winding direction: clockwise
Number of active spring turns: 4
Total number of spring turns: 6
& installed direction: green stripe on windings at cylinder head

[jimcarr]

Keeping the valve springs at the correct installed height will kep the correct pressure on the valves. Adjusting the rocker arms will do nothing for this. Yes they should be replace but with my current finances I will have to wait and plan on replacing the seats, valves and push rod tubes. I believe it will last about another 20K miles. (at least I hope so). This project was started for a smoking problem (rings) and as the valves and seats were replaced just 30K ago I was very supprised and dissapointed to see the seats were as beat as they were.