Valve adjustments--why?

beemvayman · May 11, 2022

Hi everyone,
Considering the fact that there are no more car engines--including the ones made by BMW--of any configuration that I can think of that require a valve adjustment as part of their routine service, why is it that our motorcycle engines still have this requirement? I ask this because over the years I've had a couple of bad experiences with even authorized dealers performing this task and have heard the same from other riders. That and, believe it or not, throttle body sync!
Many of us, including yours truly, don't have the knowledge or tools or space to do any much of the service that manufacturers require. Wouldn't they sell more machines if they required less complicated services?

pglaves · May 11, 2022

In a sense, this asked the wrong question. Virtually all cars now use hydraulic valve lifters/cam followers so the adjustment happens automatically within the hydraulics of the lifters. BMW motorcycles all use "solid" cam followers so manual adjustment is required to maintain the desired clearances.

So the real question is why doesn't BMW use hydraulic cam followers in its motorcycles. I have heard the erroneous opinion in the past that it is because of the horizontal cylinders in the Boxer engines, but this never deterred Subaru with their flat four engines. And it certainly fails to apply to the more upright F and G models and the upright K series wedge engines.

r0ckrat · May 11, 2022

PGlaves said:
why doesn't BMW use hydraulic cam followers in its motorcycles?

Because they are bulky and complicated to build into a motorcycle-shape... When it's under a hood, with lots of space between the wheels to deal with and weight isn't a factor, no big deal...

lee · May 11, 2022

r0ckrat said:
Because they are bulky and complicated to build into a motorcycle-shape... When it's under a hood, with lots of space between the wheels to deal with and weight isn't a factor, no big deal...

Another problem has been the hydraulic lifters did not work well in high RPM engines like bikes have.
Harley managed to make it work with their new Adventure bike. I think the redline is over 9,000 on that engine.

cabnfvr · May 12, 2022

To add to what Lee said most motorcycle engines have an aggressive cam profile. Hydraulic lifters do not work well in these applications. (The ramp shape is the issue along with the lift. Ducati went desmo decades ago for this very reason.) The shift cam won't help with this as the high rpm cam lift is still very aggressive. We've had K bikes since 1985. I have the dealer do the 600 mile adjustment, then again at 24 to 30k, then maybe 75k. The newer twins also seem to seldom need adjustment. It's not a conspiracy, just physics.

tibork · May 12, 2022

This was also one of the things I didn't want to - and still don't - do myself, you might want to check in your area or even ask here on the forum if anyone works on BMW bikes. I also found my mechanic here on the forum who is a BMW master mechanic, lives 40 minutes from my house, works out of his garage and charges FAR less than the dealer or any shop. Beside tuning my bike once a year (or two years if I don't ride much) goes through the entire bike and replaces anything needs to be replaced. It's worth looking and ask around because in my opinion some things just worth getting done by an experienced person. Hope you can find somebody.

pglaves · May 12, 2022

beemvayman said:
Wouldn't they sell more machines if they required less complicated services?

Maybe. But if lack of timely service causes damage and/or malfunction, then the decreased reliability would, once the word is out, hurt sales.

So given the design, service will be required. And yes, they could design things to require less service, but at what cost?

craydds · May 12, 2022

PGlaves said:
And yes, they could design things to require less service, but at what cost?

We all know about Harleys and hydraulic lifters. But, remember the Honda Nighthawk with hydraulic valve adjusters? Wasn't exactly a hydraulic lifter, more like a hydraulic adjusted rocker arm; the design was nifty. Those Hondas were inexpensive, bulletproof, and would run forever. Maybe one of these days BMW will make a K1600GT with hydraulic "cam followers".

brownie0486 · May 12, 2022

The design is what it is, you either accept it and it's maintenance schedule or you buy something else.

Pretty simple decision really

dieselyoda · May 12, 2022

We are returning back to solid lifters. Almost all the diesel engines I've seen had solid lifters and the ones I have seen with hydraulic lifter, didn't really impress me with weight/hp ratio.

It's pretty damn impressive that a 1500lb engine can produce damn close to 800hp with 1850ft/lbs of torque and run 10K-15K hours before in frame.

Just a thought but maybe engine manufacturers went hydraulic to reduce the number of human touches on their engines, therefore sacrificing performance for reliability.

milo · May 12, 2022

Given $90 per hour+ shop charge now I feel it's crazy for manufacturers to still design engines that require valve adjustments, other than race bikes or *very* high performance street motorcycles. Can you imagine telling the potential buyer of a Honda Accord or basic 3 series BMW that "you'll need do have the valves adjusted every 10-16,000 miles at a cost of $500?"

bigjohnsd · May 12, 2022

" For the development of the all-new Revolution Max powertrain, Harley-Davidson engineers chose to incorporate hydraulic lash adjusters (HLAs) on each cam in order to eliminate maintenance, reduce noise, and accommodate more aggressive cam profiles with reduced ramp lengths. Harley-Davidson used advanced valvetrain simulation techniques during cam design and gave careful consideration to peak loads and valve lift to ensure the HLAs work with the cam. The cam profiles were also designed with consideration for the use of an HLA at high speed. Oil aeration, which is an enemy of HLAs, was minimized throughout the powertrain. The result is a high-performance OHC engine with the benefit of hydraulic lifters. "

Read more if you are really interested - https://www.motorcycle.com/ask-mo-a...-motorcycles-use-hydraulic-valve-lifters.html

BC1100S · May 13, 2022

craydds said:
..... But, remember the Honda Nighthawk with hydraulic valve adjusters? Wasn't exactly a hydraulic lifter, more like a hydraulic adjusted rocker arm; the design was nifty. Those Hondas were inexpensive, bulletproof, and would run forever. Maybe one of these days BMW will make a K1600GT with hydraulic "cam followers".

Right on. 1985, I believe. But even Honda discontinued their use and never used them in their hi-perf engines. I believe that if oil change intervals weren't adhered to, the risk of dirt fouling the adjuster was increased - with unwanted consequences.

lee · May 13, 2022

milo said:
Given $90 per hour+ shop charge now I feel it's crazy for manufacturers to still design engines that require valve adjustments, other than race bikes or *very* high performance street motorcycles. Can you imagine telling the potential buyer of a Honda Accord or basic 3 series BMW that "you'll need do have the valves adjusted every 10-16,000 miles at a cost of $500?"

When I checked Google it appears solid lifters are common in Honda cars.

Keep in mind BMW calls for a valve check at 12,000 to 18,000 miles, not a adjustment every 12,000 miles.
It's not unusual on a K bike or Wethead boxer to go 60,000 to 70,000 miles before a adjustment is need.
On a K Bike Brick engine or Wethead boxer it does not take long to check the valves.
With my limited mechanical skills I can check the valves on both of those engines.

milo · May 13, 2022

Lee said:
When I checked Google it appears solid lifters are common in Honda cars.

Keep in mind BMW calls for a valve check at 12,000 to 18,000 miles, not a adjustment every 12,000 miles.
It's not unusual on a K bike or Wethead boxer to go 60,000 to 70,000 miles before a adjustment is need.
On a K Bike Brick engine or Wethead boxer it does not take long to check the valves.
With my limited mechanical skills I can check the valves on both of those engines.

I know some Honda car engines have solid lifters but I never hear of people checking them until 100,000 miles when spark plugs are due? I just checked for my Honda Ridgeline and it does call for valve adjusting, but only if: "Adjust the valves during services A, B, 1, 2, or 3 only if they are noisy". So they must only loosen not tighten (which is what we'd be concerned with), and mine certainly aren't noisy at 51K.

However the Africa Twin 1100 that I had called for having them checked every 16,000 miles. Just the time to remove the layers of plastic, tank, airbox, throttle bodies, etc., check valve clearances, and put it all back together was quoted as 5+ hours (over $500). "Actual adjustment will be additional time and $ but may not be necessary." The complete 16K service which includes checking valve clearance oil change, etc., called for 7-8 hours. That's a lot of money to spend every 16K, which is one of the reasons I got rid of it.

I'm happy with my Harley with hydraulic lifters. The airhead and my Guzzi V85T call for valve inspection every 6K but they're right there to get to so easy for one to do.

Omega Man · May 13, 2022

I always thought moving to “shim & bucket” style valves was a way to reduce weight and rotating mass in the engines…..especially those with higher redlines. :dunno

OM

pauls1150 · May 13, 2022

True (it's reciprocating mass, I think), along with less wear overall (when the right metals are used and properly hardened, of course!).
My Camry has solids.
Not only can hydraulic lifters "pump up" at higher revs, causing valve float, they can also collapse.
Bad boogie either way.

ragtoplvr · May 13, 2022

Pauls1150 said:
True (it's reciprocating mass, I think), along with less wear overall (when the right metals are used and properly hardened, of course!).
My Camry has solids.
Not only can hydraulic lifters "pump up" at higher revs, causing valve float, they can also collapse.
Bad boogie either way.

My 82 Honda Sabre was time consuming to adjust the rear cylinders. Because of a previous experience with a dealer valve adjust that was billed and not done, I marked the valve covers on this one. Yep, no adjusting of the rear bank. So the tech, in doing it over, left them nice and loose. I got Honda involved. Did not help. Small claims court date was ignored, summary judgment not paid. Dealer went out of business. Ended up getting less than $20 from bankruptcy court, with the film and picture developing and printing, I made nothing.. Lawyers made out well. There are dealers that have soiled the reputation of all dealers.

Rod

beemvayman · May 13, 2022

Thanks for the feedback so far everyone. The few times I've posted a question here, there's been nothing but informative and interesting responses. One of the main reasons I've been a member for 13 years is the forum.
One fact that made me think of the original question is that BMW (the car division) itself makes a 2.0 liter, 4 cyl, 322hp engine; MB has a 2.0l, 4cyl, 416hp; Volvo has one with the same configuration with 415hp. These are all high revving engines that do not require valve adjustments as far as I could find out. So why not a 1.6liter, four or six cyl, 140-160hp no-valve adjustment engine? Also, it's not only the cost--as one of the guys has said, you buy an expensive bike you should be able to pay for its upkeep, I get it--but having it done correctly. What bothers me is paying for something and not receiving it.

Anyname · May 13, 2022

I'd guess it's a combination of size and weight. You can deal with a lot of both in a car and you want as little of both on a motorcycle. Also, in my experience, shimmed valves almost never go out of spec after the break-in period and I've never have more than one shim replaced at the first servicing.

BTW, for some years, BMW car motors have used their variable valve mechanisms instead of throttle bodies to control airflow into the motor. It's a slick piece of technology and is great for both efficiency and power, but its awfully large for a motorcycle. The is a slightly old explanation:

https://www.facebook.com/Engineerin...orks-no-throttle-body-needed/483512885391727/

Valve adjustments--why?

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