The World has gone metric! It is quite possible H-D is sourcing their valves overseas, where metric valves are cheaper than having them made to inch sizes. 7mm is smaller than 5/16", so they are also going to slightly lighter valves.

 

Luke,

Are you also looking at lighter connecting rods?

 

Against Harley's $74.5 million, the global underwear market is worth just over $110 billion. Which is nothing to be sniffed at. And it keeps expanding.

Looking back at my career, I always thought I made a mistake of going into male dominate industries instead of spending more time working in women's lingerie.
I'm starting to be seduced by the attractions of the Woods 6 (240°), but I have high lift Rockers and am currently at 34° ABDC, .530" and 228°.

May be I should save that for a weekend special? I've heard the Woods is a bit of a screamer though and too noisy. That puts me off.
I think stronger rather than lighter there, and that piston speed is a wall one would hit first (they say 4250 fpm at 6000rpm is 250 fpm more than recommended) but it's better to look for responsiveness and quicker pick up.

We, my bike and I, are in our middle ages and a long term, committed relationship. Not the flush of youth. There's no rush and time for everything. It's a time of slow maturation, the appreciation of finer things, and not lust. If I was after that, I'd go for something on the side with a lot less weight on its hips than a bagger.

In short, I'll wait until the old one breaks and then agonize over all that when the time comes. It only has 8,000 miles on it. But same rules would apply. I'd need to know it was that rather than just rush out because it was "the best one". My guess I'd go stroker at that point with much greater savings on flywheels. But it's a long way off.

As with my underwear, I believe in wearing things out properly before I chuck them. I've learnt things are generally at their most comfortable just before they fall to pieces.

So, no takers with the figures of valvetrain lightening?

 

So, no takers with the figures of valvetrain lightening?

only in a drag motor would one what to take away the strength of lets say a rocker arm being used on the street

you are in fact pissing up a rope with what you have in mind to do - you cant have fast with out giving something up - you want to use theory to make it go - not going to happen - you need inches and compression along the lines of a heavily used woman - its gotta happen not talk about it

 

Funny you should say that, I built some gearboxes for a guy that drags a Shovelhead and it eats rocker arms....no wait! It eats EVERYTHING!!! mainly dollars, he's saved a lot of parasitic weight but it just keeps exploding....like I said and you said....fast =cubes

 

I'm trying to learn the principles and practice.

I have a 90 gm bottle opener in my hand (that's 2 x 45 savings per cylinder so far). I imagine shaking it up and down half an inch several thousand times a minute. Removing it is going to have some effect. Each item in the chain is better and/or stronger.

Compression, I accept. Good lubrication too. But I always preferred less weight and a close fit. H-Ds are so big and slack, you can throw anything in them and it'll work.

You know what is is, John? I am trying to get beyond the bullshit and salespitch to the facts to understand the facts.

You take just about any component and it is the same. They'll say,

Lighter is better ... yeah, well, how much lighter for how much better?
Closer tolerances are better ... yeah, well, how closer for how much better?
Bigger is better, Gee whiz alloy is the best ... Ditto. You get my point.

Don't tell me it's better, or the best, shiny or all your friends have one. Tell me how much, and what the downside is, so I can make an informed decision. I'm not addressing you but the books and magazines here.

(As you point out, for any step forward, there's generally - but not always - a downside or an element of risk, and three ways to get there. Performance/engineering is about finding the most apt compromise, e.g. weight versus rigidity and longevity, within a sensible budget).

I wasn't planning on touching rockers. Rollers have to weigh more than stock. I'm guessing additional mass probably offsets any reduced friction but the principle is god. Bigger lifts do have a small benefit in terms of performance, more the shape of the curve, but possibly a backwards step in terms of longevity in the long run (something else to wear out).

As an aside, here's another interesting quote.

 

Lighter is better up to the point at which it breaks....when it breaks is all about context, in a racing motor it can break after 50 miles and it won't matter because you'll change them every race meeting...or even every race.


Harleys are built to go for a long time, therefore parts of them are massively over-engineered and you need to break a few before you know the answers you seek because mostly Harleys get tuned on the "bigger is faster" side of things.


Closer tolerances are not always better and when they are it's often a case of quieter rather than faster and too close causes it to seize and burn money.


What is "best" is too loose a concept and with a Harley there are a great many things you do to them that will make bugger all difference because it's a tractor and not a road rocket...yeah, you can lighten stuff to make it rev but you have to add weight elsewhere to prevent it flying apart over 6K RPM...


The moral of this story for you is that you are trying to find answers where none exist (your posts suggest that you already know this) and that some of what your propose is a lot of work for no tangible return.


Wanna go faster? leave the stock valve train as it is and fit an EV27 and a Mikuni HSR 42 and see it light up...Harleys respond very well to cams and carbys, the rest is usually not worth the effort but you are welcome to play with things and any info you can give us will be greatly appreciated but them Beehive springs ain't gonna give you anything you can feel...except a headache :-)

 

no harmonic twist was involved - if your going to blow smoke do it on one of those bull **** back yard sites - many on this one are involved and have done what you have not even thought of yet --

the correct answer - different thoughts and actions on the same subject like rocker ratio - a cam with a ( lobe lift ) of .350 and a stock evo rocker ratio is 1.625 will yield .56875 in valve lift BUT - now this is what you want to know - How the axis in the ratio was ground will change the power from one rocker to another, yet having the exact same number as a total ( 1.625 ) - understanding cam dynamics is the key what does what and when it does it is the deal for power - its all in the cam timing and the fulcrum of rocker ratio and how it was ground

having said that - your question above show me you have no idea - any builder looking for max power output ( except for a TV commercial selling smoke up the *** ) knows tight is a young girl not a performance oriented engine - i will stop at that spot

i would have guessed you know someone with 150 HP 80 inch motor /// yea right

 

Ach, neither of you could answer a simple question, like how much weight reduction on the valvetrain starts to add benefits when calculating spring rates.

We got as far as a suggestion as to how many more revs how much weight reduction led to.

What's the equation for how many less ft-lbs the same reduction in the valvetrain requires? I mean, it is a simple mathematical equation.

45 gm is actually quite a lot. It's obviously going to reduce stress.

There are two approaches in all this. You can add heavier springs (which will eat your seats quicker, especially if your valves are loose in your guides). Or you can keep standard weight springs and reduce the weight and mass to end up with the same result.

So show me the math, or even logic, as why that is wrong and I'll believe you.

But I don't think you can.

I'm sorry but the "more cubes, follow the herd, and throw money at" approach does not appeal to me. I'm more of an "achieving the most with the least kind and lasting" of guy.

That actually wasn't a good recipe for a bagger, and certain not enough to do. All it'll lead to is bad fuel consumption. But may be that doesn't bother you either.

Did you ever find out the rationale for why your engineer refused take off more than 10 thou? Did he measure the chamber and squish and work it out?

It seemed bananas to me. Like he had not a clue.

Mind you, even the advice Andrews doles out on such matters is a bit lacking.
For drag racing, perhaps. For street or circuit, I'll respectfully disagree with you when it comes to head work. Close tolerances have a lot of measurable benefits; heat transfer, control of mixture, better starting, wear/longevity etc.

But it's the same across the rest of engine street or circuit. You are going to choose the closest tolerances possible and those tolerances can now be tighter than 1980s (actually 1950s) factory recommendations because tooling and materials are better. It's a different discipline to exploding down a quarter-mile.

I'm not looking for "maximum performance". It's too easy, too dependent on money, and it'd be a waste of money for what I want.

Fine, an engine right out of the factory might go 100,000 miles if luck and the legend serves you. Is there any "point" blueprinting it or improving on elements of it? Arguably not, but some people might take pleasure in it and the difference in feel at the end will be noticeable.

I probably won't ride more than 100,000 miles in the rest of my life, so why should I bother? Why bother doing anything? Why not just put gas in and ride? There's no point to any of this ****, just go buy a Honda or Kawasaki.

I am sorry, your eye caught a different part of that quote. You may be right. It was part of a conversation between Ron Dickey, Dan Baisley and Dick Hilferty but what would they know?

What caught my eye was ...

I just think there's not enough thinking outside of the box and attention paid to those "certain rpm ranges", rather than just the two max figures on the dyno.

 

The point is, it highly likely that nobody knows that answer because there are simpler ways of getting more power.


I'm no expert but I don't always assume that H-D don't have a clue and although you think you could do it better than they did it may be that you cant, a loose and heavy valve train may be the right thing for what they build and because it's tough as old boots not many will have tinkered with it.


What I do know is that Jonhjzjz has tuned Harleys for a very long time indeed and if there was a genuine gain to be had from the equation he would likely have the stats to hand but he doesn't, he does know some other stuff that you could learn from him and save yourself a heap of work.


Yes, the brutal and simplistic approach to tuning Harleys may not fit your purist mind-set but it works and it's easy to do....if you think you are onto something then you do the maths and work it out, you may find out something amazing or you may end up understanding why you can't get the answer you seek on this forum...


Have fun trying stuff, we used to have a ball tuning Jap 2-strokes but we got through a shitload of engine parts!!!