® Early Honda V4 Cams: What Really Happened

The first-generation Honda V4s were and still are magnificent testimonies of Honda's engineering prowess. From a sociological standpoint, the bikes attracted some interesting people fervent about their riding. This group has contributed significantly and meaningfully to the web community, and it is blessed because of this. One aspect of these bikes that is thoroughly represented is the issue of camshaft failures in the earliest models.
The Internet is at the same time a blessing and a curse. A blessing because it quickly codifies major thought streams on a subject. But a curse also because often the forum organism breeds a decay that colors and constrains the accumulated information. The result is a one-dimensional thinking that regards problems in very superficial ways that are often ill-informed. The fact is, despite much that can be read on the net, the controversial first generation Honda V4 cam failures are not explained by anything as simplistic or as singular as lubrication. In fact lubrication doesn't enter into the picture at all.
The truth is, similar to what goes into a cake, there are actually four critical ingredients in the extreme camshaft wear issue. Not one, not two. But, four ingredients came together in an unhappy combination that results in a sum greater than the parts, so to speak, to create our huge cake, er, cam, problem.
Ingredient 1: Historical asian cam and follower construction. Aftermarket cams are made in a number of ways, but production Japanese camshafts are pretty consistently metal castings. Cheap, in other words. This means most production Japanese cams until about 2005 are actually cast iron. Yup, cast iron. Better ones are cast steel and the very best production cams are cast moly (in the Kawasaki ZX-10R and other sportbikes, for example).
It may surprise you to learn that production camshafts are not hardened very hard. Don't believe it? You can actually drill a camshaft from a 70s or 80s Japanese street bike, and you don't even need a fancy cobalt drill bit to do it. A sharp HSS (high speed steel, the standard drill material) will drill a cam lobe easy as, uh, pie. This is probably why the cams in most 70s-80s Japanese multis wear pretty steadily, about 0.001" for every 3,000 miles.
The cam's followers (rocker arms) on the other hand are extremely hard. It is common machine engineering practice to have two close-working parts be one soft and the other hard. Thus the cams are somewhat soft, and the followers extremely hard. The cam does most of the wearing in other words. The follower wears only if the camshaft wears severely, or the engine is run low on oil.
However the follower is not hard because of superior material, but because it is plated. Many of Honda's rocker arm type engines have their rocker arms or followers hard chrome plated, chromium being an extremely hard material, thus long-wearing. But don't confuse hard chrome with decorative chrome. Same metal, different process. When a part such as a handlebar is decorative chrome plated, it is plated first with a softer metal such as copper (and often tin below that), then the chrome is put on top of the copper. The copper plating gives the chrome depth, and adds gloss as it fills in tiny imperfections in the base material.
Hard chroming on the other hand is simply putting chrome on top of the base metal, with no undercoat, which is why it is much rougher looking and was early on called flash chroming. Transmission shift forks are done this way, as well as fork tubes. And cam followers.
Ingredient 2: How the mass-produced camshaft is ground. Cast camshafts are ground to produce the planned profile and desired surface finish. Their makers cast them extremely close to final dimension, then very lightly grind them to size, because a manufacturer producing 15,000 vehicles doesn't want to waste much. In other words, the grinding aspect of cam manufacturing just barely cleans them up.
Unfortunately, cams made this way tend to have defects in the metal just below the surface, because most of the metal's impurities migrate toward the surface in a casting, even with modern technology. The very slight grinding doesn't go very far below the surface and therefore doesn't get past and remove these defects. Engineers call these pockets of impurities inclusions.
Ingredient 3: The emergence of high valve lift. Honda for decades was very conservative with valve timing and lift specs. Honda's 1970s era bikes have only 5mm (less than a quarter inch) of valve lift, and timing numbers in the 5-40/40-5 range (giving just 225 degrees open duration).
You can't appreciate how extremely moderate this was until you look at Kawasaki and Suzuki specs from the same era, typically 7mm lift and 15-55 timings. In fact, you can rev an old Honda SOHC four to the moon, way past the engine's redline in other words, and the valves will not float (that is, overpower their springs and flail around and tangle). They're just not working hard enough to. Higher lift cams require stronger springs to avoid valve float. Later, Honda started creeping toward higher lifts (beginning with the NX650), but the first major production U.S. model street Hondas to hit the 10mm mark were, you guessed it, the 1982 Magna and Sabre.
Ingredient 4: Tandem cam followers. Coinciding with this high performance cam spec was Honda's move to dual followers, that is, one cam lobe operating two valves in a four-valve cylinder head. Honda had used dual followers before, in fact, in its debut four-valve head on the 1972 XL250. But remember, the XL250 engine, like those that would follow for several years, lifted its valves only 5mm and didn't rev all that much either. What dual followers did, back then but more importantly later in the V4, was greatly increase the specific loading of the cam lobe. Now instead of two valve springs, four springs bore against the cam lobe. And in the case of the early V4, these springs were unprecedentedly strong ones (because of the high lift, remember).
Okay, so let's now mix this stuff together. Let's see how these four things worked together to create the problem: The soft cam and hard follower relationship, the skim grinding, the high lift, and the tandem cam followers.
In normal use the cam wears, and the hard chrome plating on the followers scores slightly, as the engine accumulates miles. This example is typical. Nothing to be concerned about. I have seen engines with 50,000 miles whose followers looked like this one.
However, if the engine contains cams whose inclusions are many or large, pits begin showing on that cam lobe's surface. They were always there, just below the finely ground surface of the cam, but normal wear made them visible. If as in this example the pits are extremely small, the cam is not in trouble, and may very well live a long and happly life.
But if the pits are deep enough (thus rough enough) and/or cover a significant portion of the cam lobe, the lobe becomes abrasive to the point that it begins to affect the hard chromed follower.
This rough treatment of the follower by the camshaft has severe results. The follower's plating overheats in spots and actually begins to come off the follower in strips. The follower is now a cheese grater. This is the point where things start happening, the point of no return.
With the follower's surface now a rasp-like texture forced against the cam lobe, the cam quickly tears up. If unchecked, the lobe can even be worn completely away! This example is almost to that point.
So the chain of events is: Pits develop on the cams and if large enough they excessively abrade the followers. The followers soon strip their chrome. The resultingly raspy followers then chew up the cams. Three steps, with the first cause being the pits.
The problem wasn't poor oiling. I have nothing against the many oiling line kits out there. But the idea for these kits came from a different problem altogether, one experienced by racers (including myself) having to do with cracked overhead oil lines. Team Honda and others did not do these mods for oiling reasons. Nor was the problem petroleum based engine oil. It's not oil related at all. This is precisely why some first gen V4s had big cam problems and some did not. It was all up to the happy coexistence of cam and follower, which in turn depended on a minimum of cam inclusions appearing during the normal wear process.
And it wasn't improperly adjusted valve clearances, despite Honda's effort at blaming their dealers and diverting attention with the goofy cam tool. Typical corporate nonsense, that.
Nor was it badly made camshafts. For the 750 alone Honda issued several revisions to camshaft finish, a few of them shown in this picture. They were attempts at countermeasures, but they were all bandaids.
The way to fix the problem is to go after the cause. Have your followers hard-welded. Megacycle offers this service, and it is the best solution to the problem. This eliminates the hard chrome that can strip off, and provides a hard, durable surface that is very much more difficult to hurt.
Megacycle will want to do your cams at the same time, and this is necessary. They won't in fact guarantee the followers otherwise, with good reason. They will also offer you the choice of a stock or slightly modded profile, but pick the stock one. Focus on repair, not hot-rodding. To sum up, the soft cam and hard follower relationship, the skim grinding, the high lift, and the tandem cam followers together combine to create the problem. No one of these is responsible. Cast iron cams by themselves have been used for decades with no problems resulting. These same cams were skim-ground, and that by itself never led to any issues. High valve lift appeared on many engines that never experienced cam failure, so this by itself is not responsible. And finally, tandem followers have been and continue to be used, without extreme wear resulting. It is all four together. In short, cam inclusions hurt the followers, and the followers turn around and bite the cams back. This is the problem. Upgrading the followers is the solution.

In an interesting, ironic and even serendipitous twist of reality, recently user forums have begun to accuse me of being some kind of shill or something similar for the Megacycle company. Wow! Just goes to show how one-dimensional some folks' thinking can be. Incredible!

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