Oh really
Again, hydraulic vs solid/shimmed lifter design has nothing to do with cam location
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Valve Adjustment intervals and reliability?
- Thread starter bigpoppa
- Start date
Oh really
Again, hydraulic vs solid/shimmed lifter design has nothing to do with cam location
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I'm not going to accept the presence of hydraulic lash adjusters as evidence that a H-D is "better" just because you don't have to adjust the valve clearances. All it means is that the engine is bigger and heavier and slower. The hydraulic lash adjusters make sense for the pushrod valvetrain layout that they use, because that valvetrain layout has many more opportunities for going out of whack. H-D does not manufacture any bike that is acceptable for what I want a bike to do. That doesn't mean they're all wrong - they just have no interest for me. Obviously other people like them. So be it.
There's a certain other engine manufacturer that has gotten a very good reputation for building reliable, long-lived engines, many recent examples of which use a DOHC direct-acting shim-bucket arrangement.
That would be Toyota. You might have heard of them.
There's a certain other engine manufacturer that has gotten a very good reputation for building reliable, long-lived engines, many recent examples of which use a DOHC direct-acting shim-bucket arrangement.
That would be Toyota. You might have heard of them.
Roadghost
Well-known member
Oh really
Again, hydraulic vs solid/shimmed lifter design has nothing to do with cam location
Well since you're a mechanic you would logically know more about this, especially on newer engines. Perhaps you can explain. Are there now DOHC engines with hydraulic lifters? That would be interesting. I thought they had automatic lash adjusters on newer DOHC engines? Hydraulic lifters were, to my knowledge the exclusive reserve of OHV pushrod engines.
Roadghost
Well-known member
LOL. The Harley remark was a tongue-in-cheek quip to rile the natives. Equate Harley with "the greatest" on a site like this and you quickly get a flurry of retaliatory responses. In general, the characteristics of the DOHC engine vs the OHV pushrod design represent two completely different philosophies. I don't want to go into detail for fear of riling the natives further, but the choice of engine relies on your favorite application.
boyoboy
Well-known member
I don't see a flurry of "retaliatory" responses. I do see discussion. The only inflammatory comment I see is where you call posters goofs.
VW water-cooled in-line engines are OHC with bucket-type lifters that have a built-in hydraulic lash adjuster. The ones I've had were 8-valve SOHC diesels but it's the same deal with the base 2.slow gas engine that VW built for years. These were not high-performance engines, though. Here's the layout
DOHC with "finger followers" (underneath the camshaft - not reaching over the top as with the traditional SOHC hemi-head layout that was used on Japanese inline-four bike engines for a couple decades) are compatible with stationary hydraulic lash adjusters that support the pivot of the rocker arm. This avoids the reciprocating-weight disadvantages because the lash adjuster stays put. There are a number of auto engines that are like this. It's not new - the Ford Lima 2.3 (Pinto engine) was like this.
It is possible to do this with a DOHC layout as well and many auto engines are like this. Scale it down to bike engine size, and if you want straight intake ports (which you do) then you start running out of room. Here is the 2017 GSXR1000 finger-follower valvetrain. Note that the finger-followers pivot on a shaft that runs the length of the engine ... which precludes using an individual lash adjuster on each one. (This design is not new - my '94 ZX9R used finger-followers with a rocker-shaft design)
Well I can see there's just no convincing you young guys. Blurry I know, but the calipers read .003" on standard XEROCOPY 4 bond.
~[/URL
No convincing necessary.I worked in the printing industry for 40 years and i know what paper is.It's NOT the proper tool for the job.Sure,you can get a feel for what a .003" gap is or isn't.But also have always believed in using the proper tool for the job.A set of feeler gauges,good vernier and micrometer are required to the job.If my dealer told me he checked my clearances with bond paper....well?
Brian about covered it; to be fair I may have confused the issue for you by only saying lifter instead of lifter/lash adjuster, but as Brian eluded to, engine speed usually dictates which method of valve actuation is used.
Here's a close up of a Ford OHC engine using lifters. You're basically looking at the valve train for one cylinder here (engine is overhead cam, three valves per cylinder) In this pic you can see the followers for all three valves, the exhaust valve and spring and the 2 intake lifters.
While thinking about what to use as an example of a DOHC 4-valve head with hydraulic lash adjusters, it occurred to me that I have one!
This is a cutaway of a Chrysler Pentastar 3.6 cylinder head. In this case, the pivot points of the rockers are inboard of the camshafts and this positions the valves at a wider angle.
This is a cutaway of a Chrysler Pentastar 3.6 cylinder head. In this case, the pivot points of the rockers are inboard of the camshafts and this positions the valves at a wider angle.
Looks like changing plugs on that could be a nightmare
Main nuisance is that the upper intake manifold has to come off. The plugs are buried way down there, but every DOHC-4v is like that, you just need the right spark plug socket and a long extension, that is not a big deal on its own. In a transverse installation (mine) the back three are way back in the engine compartment towards the firewall and under the base of the windshield, but every transverse V6 is like that. Typical modern vehicle ... designed to go down the assembly line easily, not designed to be serviced afterwards easily. At least they used platinum plugs that don't need replacement until 160,000 km. Honestly I'd be just as happy with the van if it had the 2.4 4 cylinder, I don't need 280 hp in a van, but they don't build them that way.
yodude
Banned
DOHC with "finger followers" (underneath the camshaft - not reaching over the top as with the traditional SOHC hemi-head layout that was used on Japanese inline-four bike engines for a couple decades) are compatible with stationary hydraulic lash adjusters that support the pivot of the rocker arm. This avoids the reciprocating-weight disadvantages because the lash adjuster stays put. There are a number of auto engines that are like this. It's not new - the Ford Lima 2.3 (Pinto engine) was like this.
It is possible to do this with a DOHC layout as well and many auto engines are like this. Scale it down to bike engine size, and if you want straight intake ports (which you do) then you start running out of room. Here is the 2017 GSXR1000 finger-follower valvetrain. Note that the finger-followers pivot on a shaft that runs the length of the engine ... which precludes using an individual lash adjuster on each one. (This design is not new - my '94 ZX9R used finger-followers with a rocker-shaft design)
early 80s suzuk 16 valve dohc adjustable forked rockers
good article on how it all led to
http://www.cycleworld.com/suzuki-gs750-and-gs1000-motorcycle-history-cycle-world-classics-remembered
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yodude
Banned
they were also used on 1200 - 1500 goldwings
I didn't know that, one more reason to keep on keeping an eye out for a clean GL1200 Standard
yodude
Banned
easy to go there & make your own, if handy with tools & have some space
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Roadghost
Well-known member
So, now that we've sorted out the hydraulic lifter vs hydraulic lash adjusters, to answer the OP's asking if a bike requiring a longer valve adjustment interval is a better bike: It seems quite clear there are long-distance motorcycles like Gold Wings, Harley Davidsons, et al. that use self-adjusting valve actuating systems that are maintenance-free. These self-adjusting systems are prone to slight distortions at high RPM so they are not usually used on extremely high revving racing bikes. High-performance engines use a solid actuation system that reacts more quickly to RPM changes and does not distort as much however, the drawback is that you will have to do periodic valve adjustments as the solid lifters or valve actuators as the case may be will wear incrementally and require adjusting.
It may stand to reason that some manufacturers are using a cheaper, softer metal in the lifters requiring a shorter mileage between adjustments. I doubt that's the case, but more expensive vehicles like the Chevrolet Corvette Z06 do use titanium in some parts of the valve system to reduce reciprocal weight and wear. A shim system on DOHC motorcycles has multiple benefits vs the old SOHC adjustable rocker system because you remove the weight of the adjusting screws, resulting in less reciprocal weight and better high RPM performance. It's also cheaper. It's also a PITA to adjust because you need shims. So, in this life there's no free ride. There's a pesky price to be paid for high-performance.
It may stand to reason that some manufacturers are using a cheaper, softer metal in the lifters requiring a shorter mileage between adjustments. I doubt that's the case, but more expensive vehicles like the Chevrolet Corvette Z06 do use titanium in some parts of the valve system to reduce reciprocal weight and wear. A shim system on DOHC motorcycles has multiple benefits vs the old SOHC adjustable rocker system because you remove the weight of the adjusting screws, resulting in less reciprocal weight and better high RPM performance. It's also cheaper. It's also a PITA to adjust because you need shims. So, in this life there's no free ride. There's a pesky price to be paid for high-performance.
Timely. Last night I was helping another member of this board with a valve clearance check on his newly imported grey-market Kawasaki ZXR400 (which he's the owner of in Czech but he just brought it here). 55,000 km on the odometer; bike has hard starting when cold and doesn't run well until warmed up. Checked carbs, all bone stock, clean inside. Stock exhaust. Spark plugs looked a little worn but decent and all four are the same - this is not the problem (although it's getting new spark plugs anyhow). Valve clearances ... out of 16 valves, 11 need shims changed. Some tight, most loose. Darn.
Fortunately, this bike uses the same finger-follower valve mechanism that my '94 ZX9R did. The finger followers are spring-loaded and you can push them out of the way to get the shim out without having to remove camshafts. It's a slick design.
Unfortunately, you need skinny fingers to get in there ...
I like this bike compared to my FZR400. Inverted forks, beefier frame and swingarm, 17" wheels in sizes that you can get good tires for. The intake runners are much better designed. The timing chain is on the end instead of in the middle. Huuuge radiator. If he puts this bike on the track and sorts out the suspension (leaking fork seal) and brakes (shot) it will be a tiny terror.
Fortunately, this bike uses the same finger-follower valve mechanism that my '94 ZX9R did. The finger followers are spring-loaded and you can push them out of the way to get the shim out without having to remove camshafts. It's a slick design.
Unfortunately, you need skinny fingers to get in there ...
I like this bike compared to my FZR400. Inverted forks, beefier frame and swingarm, 17" wheels in sizes that you can get good tires for. The intake runners are much better designed. The timing chain is on the end instead of in the middle. Huuuge radiator. If he puts this bike on the track and sorts out the suspension (leaking fork seal) and brakes (shot) it will be a tiny terror.
Most new high performance engines use Ti valves. They have a hardened coating that wears off eventually which in turn requires replacement. You cannot save them. They're expensive and don't last long under high stress. I got 4000km out of mine. When people buy a used race/track bike with 20k km on it I cringe. Stock motor or not, you're going to have to replace the $100/ea valve eventually and if you're riding the bike fairly hard that time comes quick.
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Titanium valves are hit or miss. I believe my '04 ZX10R has titanium on one side only (exhaust?) and I've had no issues in 90,000 km, and I've seen pics from the USA of those bikes crossing 100,000 miles. But this is not racetrack use.
"Durability" is not always correlated with "high performance". Same aforementioned bike had an issue with the thrust washers inside the alternator. It wasn't anything to do with the performance of the bike, it was just a design "oops". There was a service campaign (not a recall) to replace those thrust washers but only on race bikes or (interestingly) press bikes. I guess they didn't want journalists grenading the alternator during a long term test. There was no recall because usually they lasted longer than the warranty period. Mine never broke but at around 70,000 km I decided it was time to be pro-active and I went into the engine to change them.
Same bike also had an issue with the (aluminum) valve retainers cracking. I replaced those with the stronger ones used in the '08-'10 models. Completely interchangeable. The later ones probably weigh a gram more but they don't break.
The old school people like to refer to some engines as "throwaway". One common feature nowadays is coated alloy cylinder walls (instead of the old cast iron cylinder blocks, or cast iron cylinder liners cast into an aluminum block). True, they're very hard to deal with (not impossible) when it comes time for an overhaul. But ... Compared to the old cast iron cylinder walls, and when combined with the correct matching piston rings, they last practically forever and it's usually best to never touch them, and IF something happens it's often best to just get another engine. But ... Back in the old days it was pretty normal for a chevy V8 to be done after 60,000 miles. Those newfangled aluminum-engine Honda toys will never last. (I remember someone telling me our then-newfangled '78 Civic would only last 50,000 miles.) Hmmmm, how did that end up working out?
"Durability" is not always correlated with "high performance". Same aforementioned bike had an issue with the thrust washers inside the alternator. It wasn't anything to do with the performance of the bike, it was just a design "oops". There was a service campaign (not a recall) to replace those thrust washers but only on race bikes or (interestingly) press bikes. I guess they didn't want journalists grenading the alternator during a long term test. There was no recall because usually they lasted longer than the warranty period. Mine never broke but at around 70,000 km I decided it was time to be pro-active and I went into the engine to change them.
Same bike also had an issue with the (aluminum) valve retainers cracking. I replaced those with the stronger ones used in the '08-'10 models. Completely interchangeable. The later ones probably weigh a gram more but they don't break.
The old school people like to refer to some engines as "throwaway". One common feature nowadays is coated alloy cylinder walls (instead of the old cast iron cylinder blocks, or cast iron cylinder liners cast into an aluminum block). True, they're very hard to deal with (not impossible) when it comes time for an overhaul. But ... Compared to the old cast iron cylinder walls, and when combined with the correct matching piston rings, they last practically forever and it's usually best to never touch them, and IF something happens it's often best to just get another engine. But ... Back in the old days it was pretty normal for a chevy V8 to be done after 60,000 miles. Those newfangled aluminum-engine Honda toys will never last. (I remember someone telling me our then-newfangled '78 Civic would only last 50,000 miles.) Hmmmm, how did that end up working out?
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