The Honda V4 Cam Story

Written by: Robyn Landers (

Last revised: December 2005 to include Phil Rastocny's new email address and links to his articles.
Previous revision: February 2002 to include a diagram showing how to poke the cam chain tensioner.
Previous revision: June 1998 to include a preface and final update on my bike.
Previous revision: August 1994 (corrected tappet tool part number; update on my bike, upgraded radiator fan thermo-switch part number)

Copyright: may be freely copied as long as you include this header.

Foreword (June 1998)

This article is old and has evolved and does not necessarily represent the complete or current knowledge or opinion I have on the subjects it discusses. It is among the handful of oldest articles I wrote, often as postings for on USENET in the "good old days", from which has sprung a large collection on my web site. I urge you not to stop with just this article, if you are coming here from someone else's web site, but instead to begin at the beginning of my V4 web pages: so you can get the full story. Some day (I wish), I will completely overhaul my V4 web site so that old and outdated info is gone, and everything is more concisely explained.

The Cam Story

As a long-time owner of a V45 Sabre who has collected loads of information about the dreaded V4 cam problem, I have both personal experience and documented stories to pass on. My sources are articles in Motorcyclist, Cycle, and Cycle Canada magazines, as well as various Honda mechanics.

First, the engines affected. Any first and second generation V4 is affected. First generation means Sabres and Magnas. Second generation means first (VF) Interceptors. Third generation means gear-driven cams (VFR). Specifically, then (according to Motorcyclist, July 88):

It is not entirely clear why the 500 Interceptor and Magna are not on this list. They apparently are less vulnerable but it still happens. There is at least one notable design difference mentioned below. The '86-87 VFR700/750 Interceptors and the 1990+ VFR 750s (with single sided swingarm, no longer called Interceptor) are not affected because significant valve train and oil system redesign accompanied the gear driven cams.

To complicate things, a slightly different list emerges from Honda. A fellow rec.motorcyclist discussed the cam problem with the head service mechanic for the U.S. eastern seaboard, and an HRC tuner at the bike show in Valley Forge in February 1992. According to them the VF1000R Interceptor is not on the list. It was the first motor to receive gear driven cams and revised oil system, and no cases of premature cam wear have been reported, they say. Also, the late '80s Magna model (the hot-rod looking one with solid disc rear wheel and Testarossa-like side covers), while retaining the original chain driven cams, apparently received the oil system upgrades present in the VFR motors, so it is therefore much less vulnerable. And the 1994+ Magna is VFR-based and immune as well.

Now, the history of the problem. Most of these engines, especially those driven hard, wore out cam lobes, rocker faces, and cam bearing surfaces prematurely. This was especially common in Europe where the bikes are driven harder and faster. Honda came up with many explanations:

  1. Incorrect valve adjustment because of forked rocker arms.

    To avoid this, use identical feeler gauges under each fork of the rocker arm at the same time, so the rocker arm doesn't tilt. When tightening down the adjusting nuts, tighten moderately at first, then recheck the clearance, then torque it down hard.

    This problem is worsened by the fact that the cam caps don't extend very far around the tops of the cams. On the 500cc engines, and the later generation Interceptors, the cam caps extend much farther over the camshaft to hold it snugly in place. This may explain why the problem occurs less frequently in these bikes.

  2. Variation in cam-to-bearing clearance because of manufacturing method.

    To combat this, Honda developed a special tool to hold the cam in place. Any bike shop tuning a V4 had better have this tool. It doesn't cost much ($15) and isn't hard to use. Get one; even though it doesn't completely solve the problem, it is a requirement. Part number is 07979-MK30000, name is "V4 tappet adjust". The service bulletin issued with this tool recommends valve clearance of .006 inches instead of .005 that the Sabre/Magna originally specified, as well as use of premium motorcycle oil, changed frequently, and avoidance of prolonged idling.

    (To aid in valve adjustment, you probably also want to buy the special 10mm wrench for the locknuts. It's ideal for the job: very long handle so you can get adequate torque by hand, large offset between the handle and the box end so you can reach down to the locknut and keep the handle clear of the cylinder head, and very thin-walled box end to slip over the nut where there's not much clearance. Part number 07908-MB00100, "valve adjust wrench", about $15. I'm sure glad I bought one.)

  3. Improper cam chain tension.

    Various redesigned cam chain tensioners have been developed. My mechanic says none of them really work much better; other mechanics say they do work better. It's basically a screen-door arm-stop design. If your engine rattles a lot at idle but gets much smoother and quieter at 3000 to 3500 rpm, one or both cam chain tensioners are not working. Sometimes you can poke the adjuster to make it take up the slack, but this doesn't always work. The shop manual describes this procedure and includes a diagram showing how to do it.

  4. Soft cam lobe material.

    Later replacement cams use different camshaft material and hardening procedure, so they should last longer than the original cams. As most of us are aware, Honda offered an extended warranty which essentially meant free cams and rockers whenever needed. This warranty was discontinued in 1989 or so, and it costs about $1000 or so for parts (camshafts and rockers).

    Aftermarket shops such as MegaCycle can resurface and regrind your cams, which should be lots cheaper than new parts.

  5. Heat. (according to mechanics, not official Honda pronouncements)

    Despite liquid cooling, these engines do get hot. Usually the rear cams are the first to go because they get hottest. There was no official remedy for this to my knowledge, but there are a couple things you can do.

  6. Inadequate lubrication.

    According to Honda Racing, all the previous items contribute to the problem, and if you adjust the valves properly with the special tool and have new cam chain tensioners and the harder cams, you may escape the problem. But one final factor remains: inadequate quantity and quality of oil to the top end. (Apparently, Honda has upgraded the oil supply lines to allow greater flow to the head, but this isn't enough. Refer to articles by Phil Rastocny ( on do-it-yourself oil system modifications, including research of these oil supply line upgrades. Both Part One and Part Two are available on my web site.

V4 Oil System

The oil system picks up oil from the sump through a strainer and routes it two ways. One goes to the filter and from there to the crankshaft. The other goes to a T joint where one branch goes to the transmission and the other splits again to feed each cylinder head. Therefore the oil is not as clean as it could be. The oil lines are of small diameter. On '83 Interceptors there was a restrictive banjo bolt in the pipes up to the heads. This was fixed for '84, but any '83 owners should make sure theirs has been retrofitted. I'm told by Honda Canada that this bolt was not a problem in the Sabre/Magna engine and no oil system parts upgrades were ever released for the Sabre/Magna engine. (Phil has found otherwise; perhaps US models only?)

On the whole, adequate oil pressure is not developed below about 3000 to 3500 rpm. Therefore, there is often not enough oil getting to the heads. Honda Racing figured this out and modified the race bikes to pick up oil from the main gallery and take it externally to the head. This solved (not just lessened) the problem for them.

The company which designed this modification is Amol Motorcycles, Dumont, New Jersey, phone (201) 384 1103. The mod costs $175 for parts, $300 for labour including removal of engine from frame, or $110 if you remove the engine.

From about '88 to '91, Tierney-Hollen in Westlake Village, California offered a kit for $250 which is much nicer. You can install it yourself with no special tools. A collar is inserted between the oil filter and the engine case. Two braided steel hoses take fresh clean filtered oil in larger quantities to the heads. The existing oil feeds to the heads are blocked off. This looks like a winner if you want to spend the money and solve the problem once and forever. I have installed this kit on my bike and it works great. A separate write-up on this kit is available from me.

But there are less complicated ways you can help slow the onset of chewed cams (while of course using the updated valve adjustment procedure and special tool and so on as described above).

  1. Use premium quality oil, such as BelRay or Golden Spectro. Don't use 20W50. You need the pumpability of 10W40 on start-up.
  2. Change it a lot. Temperature and gearbox thrashing break down oil. Every 1500 to 2000 miles would be nice, although if you're using a synthetic, perhaps you can extend this.
  3. Avoid extended idling. Long idles mean heat buildup and low oilflow because of relatively low pressure feed to the heads.
  4. Don't cruise around in top gear at 3000 rpm. Again, oil flow.
  5. Use premium gasoline. Prevents detonation; burns cooler.
  6. Install the upgraded oil supply lines if available for your model. Consult Phil's articles for description and part numbers, as well as ways to improve on them.
  7. Do the rejetting and/or manual radiator fan mods described above.

Finally, don't be scared off a V4 just because of the cam problem. It's not as though the engine is going to explode any second. The service manager of a large Toronto dealership points out that even the worst cases were ridden into the shop running reasonably well. (This comment is from an article in Cycle Canada magazine.)

Despite all the fear of V4 cams, and the end of the huge Honda campaign to placate even the slightest cases of wear, it is entirely possible, given decent care, to have the cams stay sufficiently healthy for a good long time -- possibly longer than you would want to keep the bike anyway, and if not, start with one with good cams and spend an extra $250 for the Tierney-Hollen kit to cure the problem.

Tierney Hollen Engineering
573 Hampshire Road, Unit 233
Westlake Village, California 91361
phone (805) 499-8645

I regret to report that T-H is likely no longer in business. A couple of other rec.motorcyclists have tried to contact them in 1992 and later, without success. If you get hold of them, please let me know!

Cam History of My Bike

Okay, you say, lots of talk, but what about MY bike? (Note, I'm Canadian, so all distances are kilometers, not miles.)

I bought the bike used in 1985 with 6000 km on it. The first scheduled maintenance was at 12,800 km. No mention was made of any cam damage, but I didn't ask, so I don't know what they were like. I used Bardahl 10W40 motorcycle oil (non-synthetic). At this point, I knew nothing about V4 cam problems at all. My habits included long warm-up time (until 2 bars showed on the temperature bar-graph, as instructed in the owner's manual), and I often rode in conditions allowing lots of heat buildup, i.e. 5 bars and the rad fan coming on.

One day in the summer of '86 I got hung up in downtown Montreal traffic. The engine got really hot -- rad fan on almost full-time -- and eventually it stalled and I had to pull over and let it cool. That same summer, I went for a two-week tour of the Maritimes, accumulating 8,000 km, and, not realizing the mileage, I neglected to change the oil. So the bike went from 12,800 km to 21,375 km without an oil change. In between was the Montreal experience, and the Maritime trip with lots of prolonged high-speed running.

At 23,300 I took the bike in for a tuneup. All the cams and the rocker faces were *severely* pitted, yet I had noticed only top-end noise and some power loss. The bike was running not too badly overall (but after the tuneup it was noticeably better). The shop replaced all the camshafts and rockers under warranty, even though I was not the original owner. They used Kendall 10W40 oil. At this point I learned that many V4s had this problem but I still knew nothing about what caused it or how to prevent it.

In the spring of 1988 (!) at 27,100 I switched back to Bardahl. At 29,900, some cheap car oil went in for winter storage. The next spring it came out at 31,000 in favour of Bardahl. By now I had read some of the magazine articles on the V4 cam problem and was learning that good oil, frequently changed, and cool running were very important. So, on the second set of cams, about 10,000 km were accumulated before I adopted better habits like avoiding excess idling, avoiding heat buildup, keeping revs over 3,000 rpm to keep oil pressure up. Unfortunately my records don't mention it, but I think it was around this time (approx 32,000 km) that I installed a manual rad fan switch. I turned the rad fan on any time heat buildup was likely to occur. If the temp. gauge hit 4 bars, I'd turn the fan on. Temperature rarely got past 4 bars to 5 afterwards, and the bike never had to turn the fan on by itself -- I always got there first.

At 34,600 km, fall of '89, another tune-up was done, including oil change again with Bardahl. One lobe on one cam in the rear bank was slightly pitted on the edges. Some others showed a bit of scoring but no pitting. The rockers seemed okay. That's cam age of 11,300.

Spring of '90 saw a carb rejet. The front main jets went from 128 to 130; the rear, from 130 to 132. This was done to richen the mixture and thereby keep the top end cooler. (By now I had learned a lot more about the cam problem and was actively seeking ways to fight it.) The bike seemed to foul plugs a bit as a result.

At 36,600 km, I changed the oil, this time going to Golden Spectro synthetic 10W40. At 42,100 that was replaced with BelRay EXP, which in turn was replaced with Bardahl at 43,000 for winter storage.

In the spring of 1991 I bought a wrecked '83 Sabre from a friend. It had 18,000 km on the clock and its cams and rockers were in perfect condition. This friend had no clue if they had been replaced at its last tuneup, but my mechanic compared the camshafts to some older and newer ones and is quite certain that the cams in this bike had been replaced with ones of fairly recent design, although not the very latest. (It also seemed to have recent model camchain tensioners in it, so we decided to completely swap engines rather than just swapping the cams and rockers into my engine.)

We don't know for sure, but we guess the cams had about 5000 km on them, assuming my friend stuck to scheduled maintenance and had the bike in at 12,800 and the cams were swapped then.

These "middle model" cams, if I may call them that, have small holes drilled in the bearing surfaces to pick up oil, carry it inside the shaft, and release it through other such holes. Unlike the very latest model cams, one end of the camshaft is open to let the oil run out, whereas the latest ones are sealed on both ends, presumably to force the oil out the small holes in the bearing surfaces into the journals for support.

So, when we swapped engines, we sealed off the ends of the camshafts after measuring all bearing surface dimensions with a micrometer to make sure there were no other changes. My mechanic said that over the years the diameter of the outer bearing surfaces was changed to compensate for observed wear patterns -- they're a bit thicker than the inner bearing surfaces. I have no official word from Honda about these changes, despite my inquiries.

The condition of my cams, having been in from 23,300 to 43,000 overall, had deteriorated only slightly since last examined at 34,600, with the scoring more pronounced, the pitting on one lobe spread a little, and its rocker showing accompanying scars.

Okay, so here I am at 43,000 km on the odometer and a pretty new set of cams. At 43,200 (yes only 200 km after the previous change) I changed the oil, going to Golden Spectro. A Tierney-Hollen oil system kit was installed now as well. I swapped the carbs from the wreck in as well, seeing as mine were due for cleaning and it made the T-H kit easier to install to have the carbs out. The jetting here was 128 front and 135 rear. Strange -- seems Honda wasn't consistent even within model years. I left the jetting stock, deciding that the benefit of cooling from richer mixture was trivial compared to the other mods done and wishing to avoid the plug fouling that had been occurring.

At 44,700 I did another valve adjustment, recommended because of having had the cams out. Oil was changed at 46,800 with Motul 10W40 synthetic, and again at 51,600 back to Golden Spectro. Final change of '91 was at 55,100, with the Spectro.

In July of '92, at 56,000 km, I did another valve adjustment. This is 13,000 km with the new cams (so I hypothesize the actual cam age is about 18,000 km), T-H oil kit, strict diet of synthetic oil. Everything looked perfect inside.

Oil changes at Oct 92 (Golden Spectro oil and filter) at 60,200 km for winter storage, Sept 93 (Bardahl and no filter because I knew I'd be doing it again in a month) at 65,400 km. Yes, that's right, a whole season on the same oil, and only 5K km. 1993 was the summer that never was. Oct 93 (Bardahl and filter) at 66,300 for winter storage.

Valve adjustment in July of '94, at 71,000 km. That's 28,000 km with the new cams, and suspected cam age of 33,000 km. Changed the oil and filter, using Golden Spectro. No evidence of cam scarring or pitting. When I first got these cams I noticed a bit of discolouration on some surfaces, and I think perhaps this has worsened a bit more. When gathering the stats for this update I noticed I had used Bardahl since last fall's oil change until now. This was an oversight on my part. I guess I thought I'd be changing the oil sooner than now -- I was thinking there was already G.Spectro in it this spring/summer, and that's why I let it go a bit longer until the valve adjustment. Had I remembered it was actually Bardahl in there, I'd have changed sooner. I sure noticed the smoother shifting after changing back to Golden Spectro.

At the end of the '94 riding season, 75,500 km, I changed the oil and filter, using Golden Spectro, and stored the bike for winter. This oil stayed in for the entire 1995 riding season, at the end of which I changed the oil and filter at 83,300 km and stored the bike. I used cheap oil to sit in the crankcase over winter.

In the fall of 1995 I bought a 1993 VFR750F and as you might imagine my use of the Sabre ceased. In October of 1996 at 83,325 km I again changed the oil with cheap stuff, and again in October of 1997 at 83,480 I changed the oil with cheap stuff.

In June of 1998 I finally let go of my emotional attachment to this bike and sold it. I did a complete service for the new owner, including valve adjustment, change of all fluids, and ProLink service. At 83,580 the cams and rockers were still in excellent condition. So that's approximately 40,000 km with the Tierney-Hollen oil kit and high quality oil.

End Notes

Visit my web site for other articles in this series:

  1. Details of the Tierney Hollen V4 Oil Kit
  2. Phil Rastocny's oil system modifications, parts 1 and 2
  3. General Sabre observations
  4. Please don't stop with just this one text file. View my entire collection of V4 info at
Robyn Landers                      | "Any profit should go to Arnie's `get the        |  daemon carved on Mount Rushmore' fund."
Den0051,  KotV4                    |       - Marty Albini, DOD0550
VFR750F (his), YZF600R (hers), VF750 Sabre gone but not forgotten.