Why no valve adjustment on cars?

[CWCobra]

Guys:
The older I get, the more I reflect on why things are the way they are...

Maybe some of you experienced guys can explain to me why it is that virtually every motorcycle engine requires periodic valve clearance check/adjustment, whereas it is almost unheard of in automobile engines.

What is it about a bike's valve train that distinguishes it from an automobile, which does not require valve inspection/adjustment?

TIA,
CW

 

[Blanca BusaLess]

Modern cars have variable cam timing which directly affects valve adjustments.
Most all of of Ford/Lincoln vehicle have TWIN INDEPENDENT VARIABLE CAMSHAFT TIMING (TI-VCT) HELPS MAKE 2011 FORD MUSTANG V-6 A TRUE THOROUGHBRED | Ford Motor Company Newsroom

The system constantly adjusts itself. I would ask why our bikes don't have systems like this?

 

[hayabuser]

Most, if not all cars have hydraulic valvetrains in them, whereas motorcycles utilize solid. Hydraulic is basically maintenance free and works as designed as long as there is oil pressure in the engine, but fail at high rpms due to valve float, etc. Solid valvetrains require periodic adjustments but are very reliable at the high rpms that motorcycle engines can run at.

 

[JGGUNS]

How many cars have you jumped in lately that turn 11,500 to 13,500 RPMs? Hydraulic supported valve adjustments can't keep at up those RPMs.

 

[Busa1166]

Well that explains it to me I really never understood the difference between solid an hydraulic lifters...


Guess it's the same as the hydraulic clutch as opposed to using cable like the cruisers. Clutch adjust every time you squeeze the lever right ???

But why do cruisers keep using cable instead of hydraulic any benefit there??? I know they have aftermarket kits to change the cruisers to hydraulic.

Not to thread jack but the questions seems to have been answered

 

[JGGUNS]

The use of hydraulic clutches is really a function of the forced required to disengage the clutch. The forced (spring pressure) required to keep the clutch engaged increases as torque increases and thus the force required to disengage the clutch increases. A high torque motor such as the hayabusa, V-Max, or ZX14 uses high spring rates for clutch engagement and a cable pull clutch would be uncomfortable for most casual riders. There is also an increased expense to using hydraulic, so to keep manufacturing costs in check the cruisers usually use the lower cost option.

 

[proud dad]

Well that explains it to me I really never understood the difference between solid an hydraulic lifters...


Guess it's the same as the hydraulic clutch as opposed to using cable like the cruisers. Clutch adjust every time you squeeze the lever right ???

But why do cruisers keep using cable instead of hydraulic any benefit there??? I know they have aftermarket kits to change the cruisers to hydraulic.

Not to thread jack but the questions seems to have been answered

my vtx1800 has a hydraulic clutch......but they don't make them anymore

 

[Casperle]

Older high perf car engines did have solid lifters. Like the org. 289 Hipo that were used in the early Shelbys, which had to be adjusted.

 

[sixpack577]

There are still quite a few modern 4 and 6 cylinder car engines that the valves can be adjusted on.
For example Toyota's 4 and 6 cylinders until around 03/04. Which are also some of the most dependable and longest lasting engines out there.

 

[fallenarch]

Many say cable operated clutches have better feel, and many racers use them. But they require constant maintenance and adjustment and there is the infamous broken cable that can leave you hanging in the middle of nowhere. Hydraulic is more dependable so many street bikes go dependable rather than a better performing but high maintenance cable. There are (or were) kits to convert Busas to cable clutches. I think drag racers like them because of the better feel for launches - after that they use quick shifter and no clutch..

 

[CWCobra]

Most, if not all cars have hydraulic valvetrains in them, whereas motorcycles utilize solid. Hydraulic is basically maintenance free and works as designed as long as there is oil pressure in the engine, but fail at high rpms due to valve float, etc. Solid valvetrains require periodic adjustments but are very reliable at the high rpms that motorcycle engines can run at.

Thanks for a very clear, concise, logical answer. I appreciate it.

 

[karnage]

some of the toyotas and nissans use pucks under the cams that need checking as well.They are a ***** to do because everything has to come apart.Not sure on the bikes but from what I know as long as you maintain it right, the valve clearances should stay within spec.

 

[hayabuser]

Thanks for a very clear, concise, logical answer. I appreciate it.

You're quite welcome.

 

[majestic12]

Be glad your car had Hydro- self adjusting lifters. I had a Ford Bronco II with solid lifters and it required adjustment every six months. It was a pain.

 

[Lucid]

On that note, how much should I expect to pay for a valve job? I don't trust my attention to detail to do it myself.