® More on early Honda V4 cam failures

A lot has been said about the failure mode of first-gen Honda V4 camshafts. I have written two or three articles, and many examples of others' websites have devoted space to it, postulating this theory or that. Unfortunately, the emphasis on these sites is invariably on oiling. Unfortunately because it just isn't true. Though there are only one or two offered today, at one time there may have been as many as a dozen different oiling kit providers. Oddly (or not so oddly, considering the perverse nature of Internet user forums) these kits exist solely due to a misunderstanding. Someone probably observed that Honda's race team was using handmade external oil lines on its Interceptor-based racebikes. The assumption was apparently then made that this was to counter cam wear (though the race bikes didn't use anything resembling stock cams) and before long, everyone "knew" why V4 cams failed. However, there really is no connection, not on the race bikes and not on consumer's bikes. The race bikes used braided oil lines simply because the stock soldered steel oil lines cracked when the machines were used hard. It was common, according to American Honda, for whom I worked in the 80s. It also happened on a bike I raced.

Ask a career mechanic about lubrication-caused cam wear. Mechanics are not confused on this early V4 cam failure issue. Even without studying the issue, they know it has nothing to do with lubrication, because they know what lubrication starved cams look like. The powersports industry has always offered many opportunities to encounter engines that fail due to owner negligence. In addition, outside our industry, historically, camshaft wear in overhead cam automotive engines due to lubrication issues is also very well known. There is a huge body of emperical evidence because engine oil producers have long recognized this area of the engine as their greatest challenge, the area of the engine at which specific load bearing is highest and therefore lubrication -- by definition the separation of moving parts -- the most at risk. A mocked up overhead cam engine was even added to the American Petroleum Institute's test process for oil durability rating for this reason. Mechanics know the time of day because they handle engine parts. The auto industry at large knows the score because they had to deal with prematurely worn cams when car engines went to overhead cam design in the 70s. What you see when the cam has worn excessively due to poor lubrication is damage that looks like the cam was turned on a lathe. A dramatic, obvious, cutting appearance, with surrounding areas deeply discolored due to heat. This is not what happens in the Honda V4, whose cams get a more crumbled cheese look.

What then causes V4 cam failure? I have said it elsewhere, but it's the failure of the engine's hard chromed follower that tears up the V4's cams. The chromed surface is beat up and eventually broken through by a combination of high valve lift, tandem followers, and abrasive pits that appear in the cam's surface due to manufacturing compromises. Every engine that has this combination has suffered the same cam failure fate: Kawasaki's ZX900 series are a prime example.

Email me
© 1996-2017 Mike Nixon