Why not hydraulic valve lash "lifters"

[Dale_K]

I can remember back in the early 1970's and somebody asking the bike shop owner about hydraulic lifters on BMWs. The shop owner thought it would be wonderful but "those Germans will never do it". At the time I thought hydraulic valve lash control couldn't be done with high revving motors but I see plenty of performance cars with them and they have rev ranges similar to the 1200 (don't BMW cars use them?). The motor would be quieter and obviously maintenance would be less. I don't understand why they aren't used.

[mogu83]

A good winter time question.
Harley went to hydraulics in the early 50s and they seem to work well in their low revving street machines. Guzzi tried to go to hydraulics around 2004 and had nothing but problems, I think they're back to solids now. It does however seem that with water/oil cooled engines and better control of the operating temperature of the engine, hydraulic lifters should be possible. In an earlier life I was heavily involved in drag racing and like everyone else ran a solid lifter cam. On one engine I used a high performance hydraulic cam with very little decrease in performance, the engine would easily rev past 7k, and that was 30 years ago. Point being that a modern hydraulic lifter can easily perform in the 7/8K RPM range. I've seen cars with 250,000 miles on them with little or no lifter noise.

I can't see any reason why a company that can engineer ABS/traction control/suspension control and get almost 110 HP out of a 1200cc engine can't make a hydraulic lifter.

[crazyhorse]

I can't see any reason why a company that can engineer ABS/traction control/suspension control and get almost 110 HP out of a 1200cc engine can't make a hydraulic lifter.

probably cost, engineering and production cost?

wes

[Bill Stevenson]

Just speculation on an interesting question, but let me play devil's advocate. Why bother? BMW boxer engine heads are so easy to get at to adjust the valves that there is no special need to go to hydraulic lifters. For the original K bike engines the valves typically only needed to be adjusted once and never again. Perhaps the new transversely mounted 4 cylinder engines would benefit, but again if the valves don't require frequent adjustment, there is not practical impetus for change. On an emotional level there is tradition. Many of us take great pride in our bikes and don't mind making minor adjustments. It is one of the ways we interface with and enjoy the experience that comes with ownership of a beemer. Sure hydraulic lifters could be done, but doing so would just serve to reduce opportunities for owner involvement with our machines.

I don't know about you, but I used to enjoy rebuilding my Bing carbs every few years, points and plugs were second nature to me, I could do almost anything on my early bikes. We have gotten soft. Solid lifters represent a tip of the hat to a glorious past. I say keep 'em.

Bill

[Liam]

Hi,

I used to ride a CB750 which revved to 8500 rpm. It had hydraulic valve lifters and lived forever. If Honda could do it in the mid 1980's, BMW could do it now, if they chose to. Why not do it? I buy the argument that the gain in sale-able virtues isn't worth the development bucks. It wouldn't make an already incredible ride noticeably better.

So what's the alternative future with a big payoff? Electronic valve control. Software, not steel cams or rockers. Infinitely adjustable on the fly, less weight and friction than steel, applicable to F's and K's so the bang for buck is multiplied, and it supports the "technology leader" image. Perfect valve timing under every condition with no compromises forced on you by setting the valve timing in steel.

Liam

[deilenberger]

Hi,

I used to ride a CB750 which revved to 8500 rpm. It had hydraulic valve lifters and lived forever.

Huh?

http://www.salocal.com/sohc/tech/vlvadj/vlv.htm

http://www.nabble.com/Valve-Adjustment-td22814174.html

Which CB750 had hydraulics?

[Liam]

The CB750 DOHC engines from at least 1984 through 2000, unless they mean something signficantly different when they say "hydraulically adjusted valves."

From: http://motorbike-search-engine.co.uk/cl ... allery.php

1984 Honda CB 750SC Nighthawk The big 'Hawk incorporates all the high-performance, low-maintenance features which have made the Nighthawk so popular. A rubber-mounted in-line four-cylinder engine with oil cooler and 16 hydraulically adjusted valves, hydraulic clutch, automatic cam-chain tensioner and fully electronic ignition. The shaft drive is low on lash and maintenance free, and the 16-inch front. wheel, with TRAC anti-dive and an integrated fork brace, delivers nimble yet stable handling. The rear end is steadied by a pair of VHD shocks with four-way-adjustable rebound damping and box-section swingarm.

or from: http://wapedia.mobi/en/Honda_CB750K

As the first modern four cylinder machine from a mainstream manufacturer, [5] the term Superbike was coined to describe the CB750. [6] The bike offered other important features, both great and small that added to its compelling value: electric starter, kill switch, dual mirrors, flashing turn signals, screw on oil filter, easily maintained valves and overall smoothness and freedom from vibration both underway and at a standstill. Later models (91 on) included maintenance free hydraulic valves.

[deilenberger]

Interesting. Seems some confusion about when they started using hydraulic lifters..

Not too surprising since I basically had forgotten Honda existed by 1991.. So I could easily have missed it.

[NeilS]

Of course it's technically possible. And it's not that expensive.

The cynic in me says the reason for adjustable mechanical lifters is to preserve dealer service revenue. Many owners who will change their own oil will be afraid to adjust their valves, so a 6000-mile valve adjustment brings them into the shop at least once a year.

BTW, the main reason most cars have hydraulic lifters these days is the EPA. Anything that could cause the vehicle to fail an emissions test has to be repaired for free within the emissions warranty. And that gets expensive when you're talking about 16 (or maybe 32) valves.

[Dale_K]

Actually I'm not sure about the EPA explanation. I've had several new vehicles with mechanical lifters, a Subaru a Honda and a Dodge diesel pickup. The first valve lash check on those three is called for at 100k miles.

I would sure like to hear the R1200R motor at zero valve lash - the way it would operate if hydraulic. I bet it would be dramatically different and quieter, and "high quality". All those head fins must amplify the clicking.

I read somewhere that BMW automobiles used to have elaborate and frequent maintenance requirements and the system only changed because so many cars were being sold on leases and the lease customers refused to follow the maintenance schedule since they knew they weren't going to keep the car. Now they have "free maintenance" and very long service intervals. Not happening with the bikes though.

[motoracer8]

It took Porsche 40 years to install hydraulic cam folowers in the boxer engines, mabe BMW will figure it someday.

Ken G.