How does a manufacturer lengthen valve maintenance intervals

[seans]

What is different about certain engines that require less maintenance? This is pretty basic, but what makes valves such as those found on the 07 so much lower maintenance than, say an air-cooled Ducati?
 
I've always wondered.

[Guest Ralph]

Ducati are a bad example as they use cams to close the valves as well as open them,
nr everyone else uses springs to close them on road vehicles, but manufacturers will
run engines under test and work out a safe check mileage it will depend on material
used in components, lubrication, temperatures and design, my last bike a Suzuki was
slated for 14000 mile checks but as far as I know no one ever had to adjust them under
30,000 miles, the 07 sounds like or mine does that the clearances are on the slack side
so the 24,000 mile checks don't bother me, valves clearances on modern engines tend to
tighten up this is due to wear on the valve seats the cams and valve gear does not wear
so the valves come further up in the head and the clearance disappears, on older engines
valve gear would wear faster than the seats so they tended to open the clearances and
get noisy, with modern engines if they close up to much the valves don't quite close, leak
overheat and burn out the seats or valves, but with modern engines and synthetic oil you
can do massive mileages without adjustment many cars don't have valve checks my car as
done over 100,000 without a check and is never likely to get one.

[Cruizin]

Great question, and answer!

[Guru]

From my experience I can say that Japanese engineering is very much different compared to Italian. Tolerances on on these modern engines are nowhere near the 'it's good enough' attitude some (domestic and European) manufactures use.

[fromthecage]

also has to do with the type of metal used in the valves, springs, retainers, etc.

[rotaryryan24]

I did my valve adjustment on my WR250X at 26000 and they were spot on. Right in the middle of the recommended tolerances.

[seans]

Thanks! That clears things up quite a bit.