Cam lobe flattening '85 VF500

[DKC'sVFR]

What did taking compression on the "front range of Colorado" tell you? You are at 5000 Ft. That's approximately one mile high or nearly 1.6 Km above sea level. That makes your average local barometic pressure @ 0.83 of sea level pressure. If there were a way to calculate cylinder pressure using a straight ratio of atmospheric pressures then you should have gotten approximately .83 times 175 psi when you checked your Vf 500. That would be 145 psi on all cylinders. Even at the lowest allowable quoted pressure (142 psi) you should have read 118 psi. Worried about the condition of the "works". Don't stop at a compression test. Get a leak down test. Problem is you need an outside pressure source. So you need a friend who has a compressor. That's going to be a fair difficulty at 5000 ft. You need a very efficient air compressor to be able to get up to 175 psi or above. You will probably have to be content with 140 or less psi from the compressor. No matter, a leak down test is mostly about audible noise anyway. What you want to do is listen with the cylinder at TDC on the firing stroke (valves closed) for the passage of air. If it's a valve you will hear air rushing at the carb or the exhaust pipe of the errant cylinder. If it's the rings you will hear it at the crankcase filler blowing down past the rings. If its a bad gasket you will get bubbles in the coolant tank or noise or bubbling at the joint of the head gasket. There are parameters for how long it takes (time) for a full load of pressure introduced into a cylinder being tested to leak down a certain percentage. The tool will tell you the parameters to watch for.

I have to concure with Jamie on the "bits of metal" getting into the main and rod bearings through the filter unless the filter has been damaged or left on for too long, cloged tothe point that the oil is no longer being routed through the dirt clogged filter. As for the plumbing problem to get oil to the cam shafts and head in general, I have to say that there are an awful lot of old V4 machines from the early 80's still running around without auxillary oil lines on them. I own 5 of them. And my son has another three 500's. They have various problems but not excessive cam wear out. Maybe they are among the lucky few which had intelligent owners who did not let them run at ldle for extended periods of time before getting on and reving them up so as to get the oil pressure at the transmission up and squirting oil onto the cams. If your 500 is a "front slope bike" then maybe a previous owner, the one who amassed the majority of the miles on the bike, used to let it idle for extended periods after long cold Colorado nights in the garage or maybe outside in it. The oil had turned to molasses over night and it just couldn't make that climb up the oil pipe to the cams because the pipe was full of freezing oil until the head got hot.

I think you need to redo the compression test. This time make sure you have a fully charged battery to spin the cylinders with. Use a fully charged car battery as a jumper or get one of the battery chargers with a 75 amp starting function built into the charger to spin the starter. Buy it where you can return it after you use it for this one test if you can't afford to buy. Make sure you have the throttle open/wide open when you make the test. Try to make the compression test in the warm indoors or outside when it's not very cold, say in the sunlight afternoon, after a brilliant warm and sunny Colorado autumn day. Remove all spark plugs prior to making the test.

If you don't get the compression up to 130-140 psi get a local garage/mechanic to do a leak down test. Try to get them to let you participate. Try to get to hear the air passage noise yourself. Out here in soCal we have a retail business called 'Harbor Freight' that sells cheap Chinese made tools. You can buy a leak down tester tool for around $40. If its on sale it will sell for $30. Try to find a similar store around your part of Colorado. Then all you need is access to a compressor.

Ask the mechanic what he thinks compression taken at 5000 ft above sea level should be. Not just regarding your cycle, but for any car/truck/cycle/lawn mower that is tested at that altitude.

I think you have a viable motor. I think the low compression was a bad test run. I don't know about your cam wear problem and the issue about the soft followers. I think you might get away with just doing the head work. Another thing you could do is check oil pressure at the pressure sender tap and at the banjo fitting that feeds the cam oiler line. If you have a Harbor Freight or a store like it they can also sell you an oil pressure testing outfit for around $30. If you really think you have contamination in the main and rod bearings then you really need to check oil pressure at the oil sender tap. You have to have the motor running and warmed up to do an oil pressure test. The banjo fitting at the transmission requires a special fitting for oil pressure testing. I took the bolt off of mine and drilled and taped it for a npt or its european equivelent pipe thread. I believe the Honda uses the european pipe thread. You can get the right tap at a hardware specialty store or maybe Harbor Freight carries them as well.

Don't give up on the bike yet. You might find out that its viable if you can replace the worn cam and the followers.

[JamieDaugherty]

alright. So if it isn't a "no brainer" and you no longer sell it, are you willing to offer any help for a guy who will likely have to recreate it on his own?

I've considered that. The problem is that if you give someone info and they screw it up then you get blamed. It's happened to be a couple of times before... lesson learned the hard way.

[tinkerinWstuff]

so how is that different than any other "suggestions" offered by you or anyone else to people on a web forum?

Sorry man, I'm just a bit confused when you're like; here's what it looks like, I've done it many times, good luck to ya.....

[DKC'sVFR]

Hey TinkerinWstuff,

It's going to be a long hard winter slog coming up soon. You need to get that Cycle in a nice warm garage where you can sort things out. You want to see if its worth your time and hard earned cash before you sink arm and leg into the morass of a complete motor rebuild. You have a nice shinny new compression guage. Trust it. Get a buddy to loan you his and check your gage against his guage if you are suspicious. Or get a second compression guage at a store where you can put it back in the box it came in and return it (Walmart) and check out what the second one gets for a result for comparison.

Next, ask a local mechanic what he expects pressure to be on a car or truck when he does a compression test at 5000 ft. If he says 100 psi on all cylinders is common place on a car that runs on regular gas (most cars and trucks) I'd go with what you got. You are averaging 106 psi on all four of the Vf cylinders. You might be able to improve the low cylinder with the cam fix. And while I am thinking about it, if you have one cam lobe worn out then the others may also be faulty. If you have a worn out cam your valve will be open less time and the opening will be restricted so that will result in a lower compression reading. Your cam problem is restricting air flow into the cylinder with the problem cam. If you have one problem cam you probably have 2 or 3 or 4 problem cams. They all get lubricated from the same pipe and well.

My guess is that if you can't get compression to improve to say low 130's without a squirt of oil in all cylinders you have a stuck pig that is never going squeal again. So drive the Vf 500with low compression, you can fill it with regular instead of premium and you'll still look good when you ride. You can spend a lot of money on parts/gaskets/this and that and what do you have in the end? A Vf 500 with a racy chassis and a plastic body. You might want to go for something bigger and faster if you have to tear it apart/ say a VFR or a Ninja that does not run. Besides, after you get the real low down on compression readings at 5000 ft you can take your compression guage with you and check out the next bike before you buy it ( take a fully charged battery with you). Most guys are willing to let you do a compression test before you buy because they are curious themselves and don't have the money or time to get someone to do it for them.

There was another thread in the WORLD where a guy got two bikes for free and ended up with a good black (repainted) Vf500f. But he got it for free and he traded away the second bike for junk yard parts in San Diego. If you are going to shell out for parts you need to consider that you could be buying parts for a different more desirable bike (newer) for about the same price as the Vf500. So go slow and think about it. I gotta run to the junk yard this am. Big 1/2 price sale on the weekend at pick a part.

DKC

[tinkerinWstuff]

DKC -
Thanks for the tips but as I said earlier, I'm not concerned about the compression. The test was run cold and all I care is that they are even. The wearing cam lobe most certianly isn't affecting my compression reading as it's not worn down far enough to affect air volume at cranking rpm, maybe at 8000 RPM and most certainly enough to cause problems with carb sync but that's all beside the point.

I have a heated garage and once I get over this flu then I'll be out there messing with it again. All I'm worried about at this point is replacing any damaged rockers, cams, and reworking the oil delivery so I can ride it for a month or two and move on to the next bike on craigslist.

[Alaskan]

tinkerin, why spend tons of money and effort on an old bike that you intend to keep only a short time? That bike is not very desirable for the reason(s) Jamie noted. And I can speak with some experience because I also own a 1st Generation with serious design flaws (same problem with the rockers/cams and crappy cam chain tensioners). Frankly, if I were you I would just ride the bike until it craps out and move on to a 2nd Gen VFR. Well, I would just dump it now BEFORE it craps out, but that's just me.

[tinkerinWstuff]

because this is my version of a crossword puzzle.

I get stuff cheap, I put a couple bucks in it while staying out of the bar and off the couch, and then I sell it for what I have in to it.

And because I wouldn't be able to sleep at night if I just "dumped" it. I would either sell it as is with full disclosure or part it out if it came to a point where I couldn't get my money back out.

And here in college town, there's always demand for sporty little motorcycles for $1200 or less.

And why is it "tons of money" when I can fix it for under $100?

[Alaskan]

Keep us informed how it works out. There are several websites showing how to install oiling kits. Jamie and others have already mentioned that cam scoring is a consequence of worn out rockers, so you're probably looking at new rockers and perhaps cams. I considered fixing up my 1984 VF750F, and started with a new shock, but I lost interest given the bike's serious design flaws and the money it would have taken to rectify them - or to forestall the inevitable.

[jazclrint]

Just some info I thought you might like to know:
When I check a few years back, it was actually cheaper to have megacycles to reweld my '86 cams than to buy new ones (just under $600 at the time). I was also looking for a race cam profile, but I'm sure he does stock. But I think to have the rockers done is just as much as the cams. So about $1200 for all the cams and rockers. I would get a hold of megacycles and see what they say. I was looking at building a race engine, so if you are only going to send the actual damaged parts it may be much cheaper.

Jamie, am I wrong in remembering that the reworked cams lasted longer than stock?

Just my 2 cents.
Rich

[tinkerinWstuff]

ah, yea, no.

Craigslist, ebay, local salvage yard.

silk purse/sows ear

[JamieDaugherty]

Jamie, am I wrong in remembering that the reworked cams lasted longer than stock?

Yeah, that definitely helps. The oiling system is probably the bigger of the two problem factors, but the hardwelded rockers that Megacycle has done have been reported as doing a good job at extending the life of the top end. I say that in the past tense because I'm not sure if Megacycle even does that work anymore.

There are lots of factors involved with this topic. While there are several options and approaches, the commonly accepted solution is a modification to the top end oiling system.

[Alaskan]

Yeah, that definitely helps. The oiling system is probably the bigger of the two problem factors, but the hardwelded rockers that Megacycle has done have been reported as doing a good job at extending the life of the top end. I say that in the past tense because I'm not sure if Megacycle even does that work anymore.

There are lots of factors involved with this topic. While there are several options and approaches, the commonly accepted solution is a modification to the top end oiling system.

But, if the rockers have already worn out and have eroded the cam faces, the oiling mod alone won't restore a screwed-up top end . . . .

The point being that these bikes are fatally flawed in their design/execution. I have not researched the cam chain issue on the 500s, but I wonder whether it too plagues the VF500s.

[DKC'sVFR]

You sound like a guy who does better than break even when dealing bikes. Buy low and sell high. If Colorado is anything like California there are scads of Vf 500's sitting in peoples garages/carports/back yards just waiting to give themselves as feasts for parts cannibles. All you need is a good used parts source and you have a profit in the bag. If that Vf really does get the kind of gas mileage you claim it did there is really nothing wrong with it that a little TLC wouldn't provide.

I ran across a Vf 500 Magna in the junk yard I went to today. It was inside a van that was dragged off the street by the cops and sold at auction as a crusher. The junk yard can't legally turn around and sell the parts for use on a registered bike (the engine numbers are not allowed to be used supposedly). The junk yard is in a quandrey about how to junk it. They just want someone to haul it away for them. It's in their way. You have no problem. Just find a used parts source. If that little diamond in the rough really gets 49 mpg then you have a great running old bike thats worth $1200 to any college boy with that kind of bread. He'll be getting a good deal and a sportin' bike to boot. I'd still like you to tell us what a local mechanic has to say about compression test results at 5000 ft. What does he think is acceptable on a normal low compression car?

[JamieDaugherty]

But, if the rockers have already worn out and have eroded the cam faces, the oiling mod alone won't restore a screwed-up top end . . . .

Sure, of course you would have to replace any of the damaged components!

The point being that these bikes are fatally flawed in their design/execution. I have not researched the cam chain issue on the 500s, but I wonder whether it too plagues the VF500s.

I don't know if I use the phrase "fatally flawed in their design/execution" when it comes to a Honda! Compared to other bikes that are 25 years old the VF's are head and shoulders better. If you want to make a comparison to newer bikes then that's up to you!

[Alaskan]

Yeah, I suppose I am comparing my 1984 VF750F to a newer bike - a 2nd Gen! Not THAT much newer, really, but a much better design.

[tinkerinWstuff]

Got my cam and two rockers for $40 and both exhaust pipes for $35 at the local salvage yard. The pipes have some dings and scratches but my current pipes are rusted thru underneith.

[matt1986vf500f]

Not any longer. I'm totally slammed with suspension, wheel swap, and other CNC machined parts work right now. I was selling these kits for zero profit, and since 1) my time has some value and 2) I'm more busy now than I can handle I had to make the tough decision. It really was difficult, I believe in the top end oiling modification and my bikes have it installed. I sold a bunch of those kits and it was the first VF part I ever offered, so it was a little sentimental too.

I've got TONS more stuff than what I list on my site. I think currently I've got over 20 items for each size/model of early VF. Some of these are just too expensive for the majority of people, so I don't bother showing them on my site.

could i ask a question where do i rank in the serious VF customer

[jazclrint]

Got my cam and two rockers for $40 and both exhaust pipes for $35 at the local salvage yard. The pipes have some dings and scratches but my current pipes are rusted thru underneith.

Score! Every set of cam's I've seen are worn almost to the limit. If you've replaced the bad parts, get/make a top end oiling kit and ride the sucker. Good luck.

[DKC'sVFR]

Yall have gon and dunit now. You jes wants to take that poor little cycle apart to see wha makes it tick, tick, tick. No winter boredome for you. No cabin fever for you. Keeps the mind fresh don'it. I mean tinkerinwstuff .

But seriously, you are going to be scratching your head about the cam timing next. Take a deep breath and slowly exhale. Don't get stressed at the explanations in the manuals. Take notes on where things were and how they looked when you took them apart. And if you want a good laugh search half the threads that have gone dead, because half again of those are about trying to figure out the cam timing using the Clymer manual or just plain street sense. I leave you to your "crossword substitute". Have some big fun.
Going to the Big Pomona Classic Car Swap meet today, it's gonna be a hot one, figuratively and otherwise.

[handleyje]

For reference - Honda's Service Bulletin (3 pages) from April '87 regarding valve maintenance.

[xtravbx]

So has anyone done what the service bulletin suggests? Is that some sort of repair? Capping them like that? I don't really follow..

[JamieDaugherty]

So has anyone done what the service bulletin suggests? Is that some sort of repair? Capping them like that? I don't really follow..

Keep in mind that this service bulletin pertains to the valve spring / valve float issue and not the oiling system. The rocker arm wear is not connected to this at all.

That bulletin is really just a stop-gap to keep people from thinking it should be recalled. The valve stem caps just make the stem more durable to handle the float longer. It's the valve springs that cause the problem.

[handleyje]

Keep in mind that this service bulletin pertains to the valve spring / valve float issue and not the oiling system. The rocker arm wear is not connected to this at all.

That bulletin is really just a stop-gap to keep people from thinking it should be recalled. The valve stem caps just make the stem more durable to handle the float longer. It's the valve springs that cause the problem.

what is the cause of the valve springs being the weak link - is this due to the level of manufacturing & design that was available 25 years ago?

am i correct that more oil flow - i.e. a top end oil kit or the '86 larger oil pan/ oil pump switch helps the cams and rockers but skirts the valve spring issue?

thanks!

on a side note, a link to megacycle's VF500F page:

http://www.megacyclecams.com/catalog.../page%2036.pdf

[tinkerinWstuff]

But seriously, you are going to be scratching your head about the cam timing next. Take a deep breath and slowly exhale. Don't get stressed at the explanations in the manuals. Take notes on where things were and how they looked when you took them apart. And if you want a good laugh search half the threads that have gone dead, because half again of those are about trying to figure out the cam timing using the Clymer manual or just plain street sense. I leave you to your "crossword substitute". Have some big fun.

I used safety wire to secure both cams tightly to the timing chain when I swapped out the damaged cam for the new one and thus not loose proper timing.

The wear (from peak) was only .005 measured with a caliper (I don't have a mic at home). I was surprised not to see a lot of missing material on the old rocker, just some scoring.

[JamieDaugherty]

what is the cause of the valve springs being the weak link - is this due to the level of manufacturing & design that was available 25 years ago?

Yes. The design was pushing the limits for it's time. Think about the revs that little engine was turning - the valve springs just aren't designed to handle that very well. I think Hondas design was on the limit during development and once the production tolerances came into play it caused problems. That's just speculation of course.

Think about the power those engines make out of 500cc - it's like a VF1000 with over 150hp in stock form!!! That alone should tell you something about the VF500's.

am i correct that more oil flow - i.e. a top end oil kit or the '86 larger oil pan/ oil pump switch helps the cams and rockers but skirts the valve spring issue?

Correct, the issue is to improve the oil flow to the top end. The 86's had the same top end oiling situation. The oil pan being bigger doesn't help, and the changes to the pump were only in the relief valve to boost bottom end pressure - those things did not improve the top end oiling.

The 86's also had different part numbers for the valve springs. I'm not sure if this actually was an improvement to "fix" the problem or not, but I can tell you that the 86's will also drop valves just like the 84-85 models.

[DKC'sVFR]

Spec is for a good cam lobe to have overall no less than 1.387 in. intake max measured size, or no less than 1.383 in. exhaust max measures size. You say you have .005 in. wear. Do you mean your max overall measured size is 1.382 in. intake or 1.378 in. exhaust? Or, are you subtracting from the maximum allowed "new" cam overall measured value?

Honda quotes that minimum lobe overall is .002 below minimum allowable Spec height? So are you below the "minimum allowable overall height"?

Regardless, you have it apart and you have the cam gears fixed to the drive chain so you won't have to mess with cam timing???? Put the better of the cams back in the head. If I were you I would take your cams to a machine shop and beg them to use their 2 inch mic. They won't probably let you use it, but they will probably measure them in front of you. Be prepared with pen and paper to write down the readings. If the machine shop charges for measuring the cam lobes they are full of something unmentionable and you need to find a better machine shop to give you guidance. They might also give you a second opinion on the condition of the lobes and they might try to sell you a regrind. Don't take them up on the regrind. It just removes any hardening that might have been on the cam to begin with. If they say they will retreat the cam and make it hard again be skeptical. It's not all that easy to reharden a part and you need a hardness tester to check to see if it was done properly. If they don't have a hardness tester and can't show you the difference before and after, don't believe them.

I'd say you were a better mechanic than you let on. I think you are ready to go to bigger and better things. You need to find you a "College Boy" who wants that bike. Say, next spring when the snow is melting? I wouldn't bother with the top end oiler if you are not going to keep the bike. It will just be something you have to explain to potential buyers that might scare them away from the bike (But if it's so good why did you have to put the oiler on?). Besides, if you are going to port into the main oil galley there is always the chance that you might end up with a leaking tap. Let them put it on if they want to. You can brag about putting in the cam(s) and show them just how bad ass the bike runs with decent stock valve timing. Tell them that if they want to do an even better fix then go to VFRWorld and ...etc.

[Mobtown]

This thread is depressing.

[Jakobi]

...The 86's also had different part numbers for the valve springs. I'm not sure if this actually was an improvement to "fix" the problem or not, but I can tell you that the 86's will also drop valves just like the 84-85 models.

Jamie do you know if the springs for an '86 are interchangeable with the '84-'85 springs?

-Jake

[xtravbx]

I don't know. I love my VF500.

I just had it apart at nearly 25,000 miles to adjust valve timing, and I saw no wearing/grooving/pitting at all.

[jazclrint]

on a side note, a link to megacycle's VF500F page:

http://www.megacyclecams.com/catalog.../page%2036.pdf

Can't . . . stop . . . drooling.