Cam lobe flattening '85 VF500

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.

 

Smart guy??

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. :thumbsup: 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?

 

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

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!

 

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.

 

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

 

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.

 

Lookin' fer trouble!

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 . :biggrin:

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. :biggrin:
Going to the Big Pomona Classic Car Swap meet today, it's gonna be a hot one, figuratively and otherwise. :smile:

 

VF500F Service Bulletin #7 Valve Maintenance

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

 

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.

 

VF500F Valve Springs

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/pages/page 36.pdf

 

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.

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.

 

Does that mean you measure it as 1.38 inch?

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.

 

This thread is depressing.

 

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

-Jake

 

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.

 

Can't . . . stop . . . drooling.:biggrin: