Hydraulic Lifters

["Tom Brown" <tbrown@xxxxxxxxxxx>]

Pete:

>I was pleased to hear about the counterbalance shaft in the new engine,
>but I want more... anyone happen to know if BMW might have switched to
>hydraulic valve lifters?  Not having to check/adjust valve clearances
>would make these engines truly my ideal.

The Hex Head engine has the same brilliant valve configuration as the Oil
Head.   Hydraulic Valves are heavier and don't allow the revs that solid
lifters do.   Every effort is made to keep the valves easy to adjust (an
eccentric rather than shims) and light (really short push rods etc.).  Heck,
they even put the cylinders on the sides of the bike for you!   Try doing
maintenance on a 4 valve Ducati.  You'll be back in the BMW camp in no time.

The Hex Head engine has a stock redline of 8 grand in GS form.   I found the
engine to be very strong and willing at redline and hit the rev limiter more
than a couple times.  It's the first GS I've ever ridden that didn't run out
of breath at high RPMs.  We might expect another 500 to 1000 RPMs from the
RT/RS and S versions of this engine.

I rode a GS really hard for 3 days in France on an Edelweiss trip this year.
The balance shaft doesn't make the thing totally smooth.  You can still tell
it's a twin and feel what's going on, making it easy to maintain a constant
speed, but there are no RPMs where the engine gets rattly, like Oilheads
seem to at 5K or so.   At cruising speeds in top gear, the bike is very
smooth.   The low down power is quite good too.   My biggest issues with it
were that the throttle and brakes are a little difficult to modulate at low
speeds until you've had a day or two on the bike to adjust.   Same deal with
my Twin Spark RT, but slightly different feel.  Trans is further improved
over the '04.   I keep hitting neutral on the 1-2 shift on my RT, but didn't
have this trouble with the Hex trans.

- -TB

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End of oilheads-digest V1 #259
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