The Honda V4 Cam Story ======================== (last revised August 1992) 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): -all Sabres, including 700, 750, and 1100 -'83 to '85 700 and 750 Interceptors -'82 to '88 700 and 750 Magnas -'84 to '86 VF1000R and VF1000F Interceptors (Note the VF1000R does have gear driven cams) -'83 to '86 1100 Magnas 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 noticeable design difference mentioned below. The '86-87 VFR700/750 Interceptors and the recent 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 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 final 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. Now, the history of the problem. Most of these engines, especially those driven hard, wore out cam lobes and rocker faces 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 0797-MK30000, name is "V4 tappet adjust". [Note from Andrew: Part number should be 07979-MK30000] 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: really 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 have 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. 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). 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. - Rejet the main jets up one size to run richer and thus cooler. This may result in slightly higher fuel consumption and EPA violation, and you don't run on main jets all the time, but it does help. [Incidentally, Honda upped the main jet size on the '83 Sabre from '82, but we're not sure why.] - Install a manual over-ride on the radiator fan so you can turn the fan on *before* the engine gets too hot (when you know it is about to, such as when you're coming into stop'n'go traffic), instead of *after* it gets too hot, the way the system normally works. 6) Inadequate lubrication. [according to Honda Racing] All the previous 5 items did 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.) 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. 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. The mod costs $175 for parts, $300 for labour including removal of engine from frame, or $110 if you remove the engine. [Note from Andrew: Phone number is (201) 384-1130. The price for parts is now $250. Installation prices: $180 if you remove engine, and $50 for welding to main gallery (welding required on Magnas and Sabres only)] More recently, Tierney-Hollen in Westlake Village, California has 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. 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. I have no additional info on what is available. 7) The rejet and rad fan mods as 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. 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) 497-2679 changed to 499-8645 I regret to report that T-H may no longer be in business. A couple of other rec.motorcyclists have tried to contact them this year (1992) without success. Cam History of My Bike ---------------------- Okay, you say, lots of talk, but what about MY bike? 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 indicated 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. The summer of '86 I took a weekend trip to Montreal. During that trip we rode downtown and got hung up in traffic. The engine got really hot -- rad fan on almost full-time, and eventually it stalled and we 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 installed Kendall 10W40. 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 now, 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 km. 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. 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 within model years even. 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. ----- Robyn Landers | "Any profit should go to Arnie's `get the rblanders@math.uwaterloo.ca | daemon carved on Mount Rushmore' fund." Den0051, KotV4 | - Marty Albini, DOD0550 VF750S Sabre (his) FZX750 Fazer (hers)