Shim under bucket

[Maturecheese_imp]

Why did Honda feel the need to arrange the valve clearances the way they did, shim under bucket? What engineering/performance gain do we get from that? Surely it would have made more sense to go with the usual bucket and shim setup that is so much easier for the average bike owner to deal with, not necessitating the removal of the camshafts to adjust the valve clearances?

 

[Tev62]

The shim under bucket tend to be the smaller shims, ~7.5mm and shim over bucket the older ~25mm. Shim over bucket had to be the full size of the bucket for the cam lobe to act on. By sticking the shim under the bucket you can use a smaller diameter shim as it is now just a spacer and the bucket is directly acted on.

So now there is less weight reciprocating up and down in the valve mechanism and you can rev the engine higher (if required and dependent on any other restricting parameters). But I would have been very happy with shim over bucket as our engines are not particularly high revving.

Some alternative engine designs are well thought out. The Kawasaki W800 uses smaller shims which you can directly access by sliding the rocker arm on its shaft. A nice solution for another low revving engine.

The good news is our clearances seem to hold up very well according to this forum users' experiences.

 

[Maturecheese_imp]

The shim under bucket tend to be the smaller shims, ~7.5mm and shim over bucket the older ~25mm. Shim over bucket had to be the full size of the bucket for the cam lobe to act on. By sticking the shim under the bucket you can use a smaller diameter shim as it is now just a spacer and the bucket is directly acted on.

So now there is less weight reciprocating up and down in the valve mechanism and you can rev the engine higher (if required and dependent on any other restricting parameters). But I would have been very happy with shim over bucket as our engines are not particularly high revving.

Some alternative engine designs are well thought out. The Kawasaki W800 uses smaller shims which you can directly access by sliding the rocker arm on its shaft. A nice solution for another low revving engine.

The good news is our clearances seem to hold up very well according to this forum users' experiences.

Thank you for an informative answer. It still is a shame they chose this weight saving method when as you say our engines are not high revving, in fact I believe they are rev limited It just makes servicing the valve clearances either hard to do or expensive if you get the dealer to do it.

 

[PowerDubs_imp]

It all plays together- weight and size of the valves themselves, the spring size and tension, the 'bucket' size and weight, camshaft profile, and not least importantly- making it all fit inside the cyl head while still allowing for the shape and angles of the combustion chamber, inlet and exhaust ports, fuel injectors, spark plugs- and making it look pretty on the outside.

There is an awful lot going on inside a cylinder head.

Quite often changing one thing greatly affects something else- or negates it from even being possible.

Example- by having shim over bucket- they may have to make the springs stiffer to avoid float and throwing the shim- which may have required the springs being bigger - which might not fit the required space for diameter, or may have bound depending on lift. Stiffer springs would mean more wear and service interval, etc etc..

The variability at play are quite complex at that level.

 

[the Ferret]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

 

[Tev62]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance.

 

[Nachodaddy]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance.

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance. I like a 5K oil change schedule, since it is easier to remember to change the oil. Uneven (3,000, 7,500, etc.) numbers can get skipped if you are not paying close attention. :biker:

 

[PowerDubs_imp]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance.

I’m unfamiliar, but what is the rev limiter?

For someone like me that does not pay attention I put Harleys in the same category as the classic pushrod American cars that are perfectly happy for you to shift it 4000, 4500.

I know there are a few high-performance models of American cars that can compete with the Germans, etc. but that is a relatively recent and high cost option compared to the normal stuff.

Although I suppose for what Harley charges for the bikes they should compete and not be what they were when I was a kid.

But I would still guess with hydraulic lifters, their RPM limit is probably 7K, 75? Maybe 8K w/ a bikes smaller valves compared to cars- but I wouldn’t expect much past that.


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[GoldOxide_imp]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance.

Honda regularly used hydraulic lifters on their early-to-mid 80's DOHC 16-valve inline-4s, and I think (?) their V4s also. The inline-4s never seemed to have any maintenance issues.

 

[DrewNJ_imp]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

Yes, tis so. Particularly impressed with Harley's use of a zero-maintenance hydraulic self-adjusting lifters though. That 1250 engine has bags of character. A low 5,000-mile oil service interval but maybe that is there to give the hydraulics a fighting chance.

I’m unfamiliar, but what is the rev limiter?

For someone like me that does not pay attention I put Harleys in the same category as the classic pushrod American cars that are perfectly happy for you to shift it 4000, 4500.

I know there are a few high-performance models of American cars that can compete with the Germans, etc. but that is a relatively recent and high cost option compared to the normal stuff.

Although I suppose for what Harley charges for the bikes they should compete and not be what they were when I was a kid.

But I would still guess with hydraulic lifters, their RPM limit is probably 7K, 75? Maybe 8K w/ a bikes smaller valves compared to cars- but I wouldn’t expect much past that.


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I’m unfamiliar, but what is the rev limiter?

For someone like me that does not pay attention I put Harleys in the same category as the classic pushrod American cars that are perfectly happy for you to shift it 4000, 4500.

I know there are a few high-performance models of American cars that can compete with the Germans, etc. but that is a relatively recent and high cost option compared to the normal stuff.

Although I suppose for what Harley charges for the bikes they should compete and not be what they were when I was a kid.

But I would still guess with hydraulic lifters, their RPM limit is probably 7K, 75? Maybe 8K w/ a bikes smaller valves compared to cars- but I wouldn’t expect much past that.


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9500 It's a good sized bore but a short stroke. 105mm/72mm

 

[dave]

Honda regularly used hydraulic lifters on their early-to-mid 80's DOHC 16-valve inline-4s, and I think (?) their V4s also.

Honda's V-4s do not use hydraulic lifters.

 

[GoldOxide_imp]

Honda regularly used hydraulic lifters on their early-to-mid 80's DOHC 16-valve inline-4s, and I think (?) their V4s also.

Honda's V-4s do not use hydraulic lifters.

... yeah, wasn't sure; and too lazy to check.

Thx Dave.

 

[Maturecheese_imp]

Almost all of the manufacturers have adopted that system as the most dependable and trouble free Honda,Yamaha, Suzuki, Triumph etc

I wasn't aware of that. Still it also makes servicing it it harder for the average home mechanic and therefore makes more money for the dealers, a common theme these days unfortunately. Some of us are not overly endowed with funds and sadly motorcycling has become a hobby of the better off, not as it was in my youth.

I miss the simplicity of my bikes of the past like the Suzuki GS 550 and Yamaha XS 650. Without doing any real research (my bad) one of the reasons I went for an air cooled 4 was simplicity (I wanted an XJR 1300 but the fuel economy put me off) but it seems there are no motorcycles out there that are simple and basic anymore. I am, I must admit, out of practice after spending a couple of decades bikeless but even a simple job like removing the front sprocket involves removing a pump first and without a Haynes I'm reluctant to do it. Technology moves on i suppose and this forum is very useful at providing help and info so hats off to it.

 

[the Ferret]

Only a few do their own home mechanics, and most don't put enough miles on them to need to get into the internals before moving on to the next bike. It's not unusual to see 5-10 year old bikes for sale with less than 5,000 miles. Way before the first valve service is due. As a matter of fact they are just called valve "inspections" these days (to make sure they are still in spec) and that doesn't require cam removal. It's also not unusual on this forum and others I have been on for the home mechanic type, who do check their valve adjustments frequently to find them still in spec after 25-50,000 miles. My Honda ST 1300 never required a valve adjustment in 110,000 miles.

I don't think the manufacturers went into it with the thought that if they went with the shim under bucket that they would make a lot of money from valve services.

The XS 650's had a simpler adjustment but required adjusting more frequently as those valve arrangements were not as stable/reliable (I had (3) 650 Yamahas, a 73, a 79 and an 81). Having worked in the industry for 17 years from 1972-1989 I can tell you only a few did their own mechanics back then too. Most when needing service, other than an oil change or chain adjustment, brought their bikes into dealerships for service. Plus today working on stuff is a dying art. Millenials and Gen Z's have little desire to own vehicles much less work on them.

Putting air in a tire is really a simple thing, but you'd be surprised at how many motorcyclists are not even any good at keeping up with that simple task at home.

 

[peterbaron]

^^a very true statement^^
*****

 

[Gone in 60]

Since most of you guys say that the valve clearances mostly stay in spec, I've figured that mine are still fine... right? I must admit that I have adopted the 12000 year interval that was for the later bikes, and, even as a meticulous mechanic, I don't feel the least bit guilty about it. Plus, the last time I did a valve adjustment, on my Triumph, it became a week-long affair that involved building a tool to retrieve a small bit that had fallen into the crank case.

And that was just two cylinders.

Some people can't even be bothered with looking at their tires, let alone checking the air. A few days ago, I was following a guy on a Harley who had a white stripe of cords easily visible on the back tire. I mentioned it to him, and he said "Huh, didn't notice.. thanks, I'll have it looked at."

The one that gets me, not to get too far off-topic, is seeing a car with the license plate dangling from one screw. I think to myself "Is dealing with the nightmarish quagmire of the DMV to get a replacement for a lost plate really more appealing than finding one screw and sticking it in a hole?"

 

[Nachodaddy]

"There's a screw in my license plate? I better get that looked at."

 

[Mixagon_imp]

It says in my manual valve clearance check every 8000 miles or 12000km.
I'm not worried about ignoring the first check and doubt I will ever reach the second check so that's me sorted
My cb1100 is now just over 1000miles as its only used in good weather, I use my cb500x much more so that helps keep the 1100 milage low.

The lack of owner's maintenance on some bikes surprises me, I often see really bad rusted chains nearly dragging on the road.
One guy once asked me if I thought his clutch was slipping and on its way out. He showed me by trying to pull away with the front brake on and the bike not stalling.
I couldn't believe what I saw.... the chain was slipping over the rear sprocket because the rear sprocket was toothless, and he was riding like that.

 

[PowerDubs_imp]

I can only imagine the noise and vibration that it had to make on a rear sprocket before it ever got to the point of slipping.

When I was young a friend of mine wanted to go out and ride dirt bikes with me so he bought an old 1970s Yamaha for a couple hundred dollars.

About a month later and he was on the street doing burnouts by holding in the front brake, reving and dropping the clutch, a few times while tearing up and down the road and then went to do it again all you hear is rubbing it nothing was happening. Turns out the chain was now spinning over what was left of the front sprocket

But in that situation it was a very beat up cheap bike, front sprocket out of view, and since it was a two stroke it was loud and rough anyway.


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[dave]

Honda's V-4s do not use hydraulic lifters.
[/QUOTE]

... yeah, wasn't sure; and too lazy to check.

Thx Dave.
[/QUOTE]
You're welcome!

My 1998 Honda VFR800 (best bike I ever owned) has gear driven cams. This makes it SO much easier to adjust the valves - no cam chain or cam chain sprocket(s) to remove.

I performed the first two valve inspections on this bike at the recommended mileage, and both times all the clearances were in spec. I didn't have to adjust any valves until I reached 56,000 miles (bike now has 116,000 miles).