As usual, John, you avoid actually answering the question ... or explaining how the valves are going to magically jump across a sizeable gap ... and just huff and puff around, distracting and demeaning others instead.

I didn't "show a TC". I put up a link to Rev Perf video talking about their services, showing their shop, and qualified what did not apply to an Evo. They did not have a video of an Evo ... so I put up a link to someone working on one.

What did you do?

OK ... explain to us why an EV27, 10:1 pistons running at a corrected 9:1 (-ish), and a 35 thou squish is "bad", or won't work, or will cause problems.

Or explain to us why an $180 dollar stock piston is a better investment than cutting a notch in his existing ones, or using a $30 NOS/takeoff OEM one, and qualify how much?

(BTW, less BS and more action ... what would you charge to notch his pistons, or would you do it out of goodwill for him?)

---

Here's some more backup from me.

S&S used those JCC pistons in their (vintage) racer for more than 5 years, and rate them. Good enough? The company, JCC, is world's largest and supplies about 100 OEM factories including Ford, Daimler Chrysler, Mitsubishi, Yamaha, Kawasaki, Suzuki and Honda etc with their OEM pistons. They actually make the Hepolite pistons (they probably make about 70% of the pistons used in the world).

He doesn't need to spend $180 on religious fetish icons (e.g. Wisecos) if he's running them at less than 8:1 ... which he will be if he does not resolve the inherent deficiencies in his engine.

True or false?

I argue, if he really wants to spend $180 (approx), then he should make the best of it as it will cost him no more, and there is no additional risk to doing it properly.

Here you go Glide ... here's a substantive response instead, and why it is worth considering.

Firstly, this "recipe" I am talking about is not mine. It's one that has been done on 1,000s of Evo. Probably 10,000s of Evo. It's not even radical. It's about as radical as a well tuned 1960s motorcycle was. It's safe and will improve your engine all around, from starting to economy, to grunt.

Secondly, ask "why it is worth considering? Why would you consider it?" Remember, I'm not in the business of taking money off you. I'm trying to save you some, so you can spend it on improving your bike elsewhere.

You can get more and better for less. Do you want it, or do you want the sticker for your tool box?

I would say answer lies in when you install a cam with a later intake closing, you're actually decreasing your compression further. And you already have low compression. So firstly, it's wise to raise the compression to the engine's optimum, designed level. Secondly, it's safe to raise it a little more to suit the new cam.

If you have an eye for detail, you'll notice in that discussion I quoted, the end user actually came back months later and reported that the actuall compression was *exactly* as it was mathematically calculated out to be.

Here's a typical ... slightly exaggerated ... dyno sheet of what we are taking about. I say, "slightly exaggerated" because it was made worse by the choice of exhaust. The black lines are stock. The red lines are a "performance tune". Yes, it makes more maximum torque and hp ... but do you see the drop? In this case, it is between 3,000 and 3,500 rpm?

Which rpm do you usually ride or cruise at most of the time? Which rpm do you need instant pick up?

This is what we are aiming to avoid and resolve. It's not about "high performance" or "max power". It's not radical or threatening. It's just about making the engine run as it should have done if the engineers had been allowed to.

Rather than just insult me, someone shoot me down by telling me *why* am wrong.

Yes, I've just lost the company $100s of dollars from selling you stuff you don't need (e.g. "Hey, buy a 42 mm Mikuni to go with those Wisecos too. That'll fix it! $800 kerching"). But, technically, what is bad or wrong with the recipe or methodology?

I say the answer is ... nothing. Please prove me wrong.



Those little dips are typical of EV27s and similar that are not done properly.

 

Here's a quick lash up you should be able to do at home. You don't need a gauge, you could use a caliper and get a good enough reading. Put a flat over the face of the head, and push the valve down until it hits. These heads have had a .050" skim and the valve hits at .240" lift. .240" less .060" is .180".

Now, the 27 does lift to I .182" and E .166" at TDC ... but remember, a) these have been skimmed and yours haven't, b) you need to add a 30 or 45 thou gasket, and c) your piston is likely 10 or 15 thou further down cylinder. Therefore, you have an additional 110 thou 'vertical' clearance. You can fake up gaskets/squish etc using feeler gauges or work it out geometrically as the angle of the valve travel is a known factor. It works out to be about ... 130 thou travel?

60 to 80 thou is a good clearance, so you have additional 70 safety margin ... without even notching the pistons. Therefore, I'd say you're safe to clay up the piston tops, reassemble the engine, and turn it over to see what it really says. Likely it will say the same.

My deductions would be that the valves that hit the pistons were bigger, the bike had heads which were skimmed, or there some other factor to make them do so John is telling us about. Like revved to 8,000 rpm.

Otherwise, explain how they hit.

 

The magic jump in gap in theory and engineering is that although the stock cam compared the ev 27 have similar intake valve closings at 36/38* it's all in the way the cam is ground and clearances @tdc. The ev 27 produces approximately .100" of lift @tdc over the stock cam. A stock motor from HD has roughly .070" valve clearance @tdc so if you put in that .100" lift more @tdc. Bang pow #÷!$@&."';;;. And there you have it...**** wish i listened to John.....

 

No, I think all you're only showing is that did not read or you didn't understand what I showed.

I'll try again,

An Evo stock cam (L) comes up at 0.091" and 0.083" TDC lift.

Yes, as you say, an EV27 comes at 0.182" and 0.166" TDC lift.

But there is approx 0.370" of travel before a valve would hit a notchless piston at TDC.

So how does it jump from 0.240" (0.180" plus 60 thou for clearance) to 0.370"?

Now, I've stood and watched a dial gauge on a real head measure exactly what the mathematics says, and it does. Actually, it was a little more than 0.370" travel.

Example

With a 50 thou skim, and a 30 thou gasket, this head would still allow for .280" travel (lift + clearance) ... on a piston without notches.

All the EV27 needs is .240" (0.182" + 60).

It isn't even going to be close.

Either he buys his valves from Lee Harvey Oswald, or there was something else was going on in those engines that broke that John isn't telling us about, and it's misleading; e.g. skim, plus bigger cam, plus bigger valves.

 

Luke, are you a garage hack or a professional well known mechanic trying to stay on the DL? If you are it's fine. As someone who helps run one of the largest firearms specific forums on the net, I talk to lots of gun wrag writers and other well known people in the firearms industry who wish to be kept anonymous to the general membership. If you are that way it's fine, but if not then please give it up. John has a long list of credentials that a lot of people here don't know about that makes the information he gives stand on that much more solid ground. He isn't lying and isn't giving bad information. Unless you have the same experience and qualifications you're out of your league here.

 

As usual, John, you avoid actually answering the question ... or explaining how the valves are going to magically jump across a sizeable gap ... and just huff and puff around, distracting and demeaning others instead.

magically jump across a sizeable gap

 

YEP. I think its Luke

 

Honestly. I know of three individuals who have roughly a 100 years of experience (that's a century) of combined knowledge and not from a book or a video but from working hard in their shops to support their family. A full time job that really has no benefits. My hats are off to you for I now that i can trust your judgement and rely on your advice (and I have without fatal consequence). You don't have to answer phones or e-mails to help the less educated but you do. there is a large following for those that give most of their lives to help others and I will stand by you as well as respect you for being there when needed. I wish I had the ***** to do what you do for my Lively hood..... Thank you........

 

This forum should be about facts, and helping others understand, not defending others pride.

What has John actually said, or offered? What is his recommended "Lee Harvey Oswald" build? And what have you achieved so far?

You've freaked a guy, who was a little unsure - and is probably being run around and exploited by dealers - into spending $200 he does not need to ... which will achieve him a sub-par result.

Well done.

And now rather than address the bits of metal and calculations - which I guessing a few of you, if you are honest, would have to admit you cannot tell if they are correct or not - you're creating a drama like some schoolgirls defending their Queen B, and attacking the guy who is trying to help him save money and/or get a better end result.

What I would like to ask John is, if he is going to get into serious discussions, is please use a keyboard rather than thumbs on an iPhone.

If John's got a jig, the amount of time it would take to cut Glide's pistons is less than writing this post. Tighten, cut ... tighten, cut ... job's done. If he takes 10 minutes to do it, he had a cigarette break in the middle.

OK, I've put my cards on the table;

It's either, Now, Now, if John is going to tell me I am bad, wrong, evil or a "Jackass" for writing that. I'd like him to go on the record why, from a technical point of view, you'd want to pay $200+ more (plus build costs) for a 60 thou squish, 7.something:1 compression engine.

Guys, the actual activities involved are really no more complex than those wooden blocks you banged into holes as a kid, and the mathematics you did when you were 12 years old. It's not rocket science. You cannot see it, but you can trust the math (and clay).

Empower yourself with understanding and experience. Don't just spend money on branded lucky charms (Wiseco) and make donations to the Priests of the Workshop in the hope they overcoming your FUD (fear, uncertainty and doubt).

Here's how you work it out roughly enough to be safe (pedants note the disclaimer).



What's the angle b ... 27 or 31° (inlet or exhaust)? Angle c is 90°. Side a is; the thickness of your gasket +/- the distance up or down the cylinder your piston top is at TDC, e.g. 45 (gasket) + 15 (piston down the hole) = 60 thou.

Therefore, side c - the amount of additional travel you have - is 70 thou.

Add that 70 thou - which is more than the amount of advisable clearance - to the distance we measured above (where the valve hits the metal rule).

So, what is that now ... 0.280" plus 0.070" = 0.350"? (an example, not his actual figure - without piston cut outs).

All we needed was 0.240", so where's the problem? There are other little considerations, but that's detail enough for just now.

Prove me wrong. Don't just say, "some guy some where once broke some bike so it cant be done".

 

Luke - you missed it completely the type of roller lifter used by harley and many others is what the issue really is - it has become evident to me you do not know what really goes on

harley factory red line is tied into this little tid bit -- ((( 5500 RPMS))) is the spot the lifter starts to pump out ( you do know the lifter is pre loaded as in a pushrod designated length )

its a hydraulic lifter and its pre loaded down ( just taking into account the stock valve spring installed height pressures as it relates to a rymac when checking it ) the lifter starts to pump out - anyone old enough to have owned a 396 chevelle will know what happens at 5800 PRMs the lifters flatten out and make a hell of a racket under the hood ) in a harley they also pump out in bigger lift cams with out enough valve spring pressure the rocker will make contact with the under side of the top rocker box cover ( and it cracks it ) so math equations wont get you the ( magically jump across a sizeable gap ) but a pumping out lifter will get you a bent valve are or a broken off bottom of a valve guide --

well one would say why did you just say that i just did as it is unnecessary info in replacing a cam in a stock motor with piston reliefs as it were