4 & 6 or 6 & 8 ?

[Ray from Indiana]

I've been setting the valves on my R100 at 4 & 6 thou since I bought it. Lately I read something about setting them to 6 & 8.

What are the masses setting them to?

[dougie]

Last time I checked mine were at 3 thou and 7 thou.
I hear a nice soft ticking.
I use GSPD's method ( 1 flat, 1/2 flat on the adjusters).

[Deleted User 62]

I've been setting the valves on my R100 at 4 & 6 thou since I bought it. Lately I read something about setting them to 6 & 8.

What are the masses setting them to?

The factory handbook says 6 and 8, but the aftermarket manuals are now recommending 4 on intake. They can be tighter, and thus quieter, but you may want to check your valve clearances more often.

[SteveD]

I can't remember what GSPD's recommendation equated to in measurement, but they were a tad tighter than most??

[Deleted User 287]

I can't remember what GSPD's recommendation equated to in measurement, but they were a tad tighter than most??

Yes. At least that is how I remember it.

[mattcfish]

I've been setting the valves on my R100 at 4 & 6 thou since I bought it. Lately I read something about setting them to 6 & 8.

What are the masses setting them to?

The factory handbook says 6 and 8, but the aftermarket manuals are now recommending 4 on intake. They can be tighter, and thus quieter, but you may want to check your valve clearances more often.

Yeah, I've read 4 and 8, just to confuse you more.

[Zombie Master]

My owners manual says 4 and 6 for a 1984 R100. They've stayed put for several checks. I'll just leave them alone. Bike starts quickly and easy.

[Ken in Oklahoma]

My owners manual says 4 and 6 for a 1984 R100.

As I understand it those were the right numbers as recommended by God and BMW. But then exhaust valve seat recession showed up when "they" took away leaded gas. Fortunately BMW was on it and specified hardened seats for their new motorcycles to fix the seat recession problem. And it was very effective. But the bad news was that now the exhaust valves themselves started tuliping, which served to decrease clearances just as the valve seat erosion problem did.

So it became convention to add a couple thousandths to the exhaust valve clearance to get a little more "headroom" before the clearances got to zero.


Ken

[Jean]

Back in 2009, I set the valves on my R100s (78) to Intake = 0.15mm, Exhaust = 0.20mm as recommended by Paul Glaves. Be careful, these measurements are in mm. anyhow, seems to be good settings and haven't changed over 4K miles. Go figure.

[Ken in Oklahoma]

Back in 2009, I set the valves on my R100s (78) to Intake = 0.15mm, Exhaust = 0.20mm as recommended by Paul Glaves. Be careful, these measurements are in mm. anyhow, seems to be good settings and haven't changed over 4K miles. Go figure.

Similarly I haven't noticed any significant tightening up of clearances on my '77 R100/7 or '77S bikes. I'm guessing it has a lot to do with how hard a person drives. Most of my airhead time is spent touring with only occasional "sporty" forays.



Ken