1986 VF500 valve spring data

We all know the VF500 drops valves. Plenty of tales of woe have been posted here and the other groups. I have a 1986 VF500F2F which has about 22k miles. I am sure this is genuine. I bought it in 2011 when it had 18K miles so I haven’t exactly used it a lot. I have other modern bikes that do the heavy lifting. I bought the VF because I like it and the engines are fun to work on.
I have two spare engines. One came with a 86 spares bike I bought from a local dealer for EUR100 and the other (also 86) I bought from Ebay UK from a breaker for GBP225. The spares bikes engine speedo said 37K miles which as we know is a lot for this engine. The Ebay engine was supposed to have only done 3K miles and the breaker eventually convinced me this was genuine. The spares bike was a US model imported to Ireland sometime in the distant past.
I have a tool for removing valve spring (search for it on Ebay if interested). It works well. I figured I would check the valve springs on these two engines. I checked the free length of all 32 springs on the spares bike engine. Now I can’t guarantee the mileage on this engine. The speedo said 37K miles but who knows….
From my manual, the inner spring free length is 32.35mm with a service limit 30.65 mm, and the outer spring is 35.66mm with a service limit 34.36 mm.
ALL the springs were fine. The smallest outer was 35.1 mm and the smallest inner was 32.9 mm. No idea why the inner springs are bigger than spec. Remember this was after 37K miles. I also checked the camshaft lobes for wear and they were all well in spec.
I only checked one set from the Ebay engine and these were 36.0 mm and 33.6 mm. So much bigger than the spec. Again no idea why. Maybe it’s the way I measure them.
So in summary 37K unverified miles has not shortened the springs below the service limit. This doesn’t tell us much about engine longevity but I suppose it’s something to know.

 

Hey Jeremy,

I have bought new (NOS) springs and have a spare engine and several spare heads. I have found the same thing. I will tell you that I have seen damaged valve tips on almost all the heads with anything more than 10k miles on them. I recently pulled apart a 1986 set of heads and out of all 16 valves only two came out without having to grind the widened tip down at least a bit. You can say that pretty much all the valve tips were hammered at least enough that they were too wide to fit through the guide. Two were really bad. I assume that although the springs maintain their height, they must just not be adequate for any high rpm use which these engines beg for. Anyway, probably the only solution is to have modern material springs installed and probably all new valves too. I tried getting modern springs but the person who supplied them gave me a totally wrong set that were too tall and too wide. A contributing factor is probably the old valves themselves. I had new springs, retainers and cotters and 3 brand new (NOS) valves to eliminate any valves with any tip marks no matter how minor. The rest I installed were all my undamaged, new looking used valves BUT even after all that "precautionary work," I had one just break a couple of months ago right below the cotter groove and ruined my engine. My latest "solution" is for the 86 spare engine I had and that was to purchase an entire brand new set of valves for a VTR 250 and that is what I'm running now, everything seems to be fine right now BUT everything also seemed great when I was doing 90 mph with my newly rebuilt 84 engine, lost power and then heard the death rattle. All my valves on that 84 engine looked brand new, no valve tip damage at all and all were adjusted exactly to spec. If I didn't have so many spare parts and patience, I'd have made this bike just a garage ornament already but I love it. I love the punishment too I guess for some unknown deranged reason.
By the way, my "droppy" (figured I'd make up a name for these common problems) was from the left back (#1 Cyl?) and it was a brand new looking INTAKE valve with only a couple thousand miles on the springs, valve clearance just checked, running nice, cool and strong... a disaster waiting to happen is what we ride here. I'll post a picture for the ever-growing carnage collections. The photo for your perusal shows how after the valve sheared under the cotter it (probably) was sucked down into the combustion chamber, then crashed into the piston making the head break off which bounced around inside chopping up the piston and head and then it was finally pushed up right up into the exhaust valve shoving that valve up into the exhaust port causing the rocker arm on that valve to break....When I took it apart, the severed valve tip and cotters/locks were still intact in the retainer... good times! If this happens to you, you'll know by the noise and loss of power but strangely enough, my engine never quit and the revs shot up to about 8k at "idle" with no throttle applied when I pulled in the clutch as I pulled over to the middle of the busy freeway where I was stuck for an hour waiting for the tow truck. I have no idea what that with the high revs was all about. I know there are a lucky few out there with high miles and zero problems but that must be one out of 100 of these at best. It really seems that if you're running your original valves on your original springs, it isn't really a question of IF but more likely just WHEN it'll happen to you too. Good luck! Hope you're not doing 90 in the fast lane of a busy freeway when it happens to you!!

 

Sorry to hear, but thanks for posting. It's really strange and interesting. All the valve tips in my high mileage engine looked fine. Some pitting in the middle of the valve but no mushrooming. I do know there was a service bulletin about this and Honda supplied little hardened steel caps to fit over the tips. In my 3K mile engine of the 8 valves I examined 7 were pristine but one looked a bit hammered. I am working away from home at the moment so when I get back I will post some pictures.

 

when I rebuilt the 84 engine, I took out the valves that had any marks at all. I just kept the ones with the perfect, new looking tips. I guess Honda just used the same kind of metal for their valves in all kinds of different engines. Apparently what worked great in millions of other bikes just isn't good enough after 30+ years for our little VF's. I haven't seen another one on the road here in San Diego in many many years now. I don't know if I'll be able to find another engine after this one blows up too. Why do we do this to ourselves? It really is highly NOT RECOMMENDED to try to keep one of these alive. If this hadn't been my first bike that I bought new way back in 1984... none of this would have ever happened to me! However, it has forced me to learn tons of stuff I never would have tried otherwise.

 

Yes, its a challenge alright. I knew all about the engine issues when I bought my VF500 in 2011. It was one of the reasons I bought it. It's such a pity the valve is destroyed when it drops. You can learn a lot from fracture surfaces and I have access to all the required kit, but they get bounced around so much there's nothing left of any use. Almost certainly a fatigue failure of some description.

 

Something else to bear in mind is that modern springs are not necessarily going to fix the problem anyway. The design of the springs will have to stay the same to fit the head, spring diameter, free length etc and the coil and wire thickness will also need to stay the same to give the same spring constant and therefore the same dynamic behaviour. A more sophisticated spring steel might resist taking a permanent set better (stronger and more creep resistant) but as your observations and mine show, this doesn't seem to be the issue. Valves made from more exotic materials that resist fatigue is a better option. This is possible but expensive.

 

A complete set of modern springs with retainers, seats and keepers runs about $800 but what I got didn't fit so I returned them. The guy at RD said he could do it though as long as I sent him some samples to go by. Exotic valve materials also carry an exotic price and there aren't any that I know of anyway. That throws the expense way over what the bike is worth on just springs and valves for me. In wanting my last spare engine to live a bit longer, I bought all new valves for the VTR250 from Japan and installed those. I'll just hope this will last me at least a couple more years. Even now (with my luck), the crankshaft will probably break or the main and/or rod bearings will go bad and those are super hard to find. There may not even be any left out there that I would need. With this bike, it's much better to have lots of luck instead of lots of spare parts.

 

So you can confirm that VTR250 valves fit the 86 VF500? That is useful to know. I was always under the impression the VTR250 valves were a direct fit for the 84/85 VF500 head and not the 86.

Spare engines and bikes are still pretty common in the UK. There's nearly always a few on Ebay. Over the Xmas holiday I will be swapping my OE engine (22K miles) for my Ebay engine with very low miles (3k).
THe Ebay engine has much better compression and I don't actually know if it has another hidden problem so I reckon I will fit it and find out. Might as well get the practice in for I when I have to do it in anger

 

Yes sir! Indeed confirmed. I have installed ALL brand new vtr250/MC20 SPADA valves in my 86 engine and to top it off I'm running my still new (1500 miles new) 84/85 springs in my 86 engine. Everything runs perfectly fine...so far no issues. The exhaust valves are the same for the 84/85 and 86. Only the intakes are different for the 84/85 compared to the 86. Again, 86 shares the same intakes (and exhaust) as the VTR250/MC20 SPADA.

 

OK. Thank you replying. The VT250 was a really short lived model in the UK. Maybe 2 years at the most. It's really interesting that you have fitted your 84/85 springs to the 86. The partnumbers of the 86 springs are different to the 84/85 on CMSNL and yet the freelength specs are the same. I assumed the springs had a different spring constant (wire diameter or number of coils) to account for this but you would suggest not.

If you have new springs AND valves you must be OK for a a decent number of miles.

 

the lift for the 86 cams is slightly less than the 84/85 and since the exhaust valves are the same for both, I figured it would work ok not pushing them with any extra lift, besides, I'd read of other guys using 84/85 springs on their 86's. Who knows? Either way, it wasn't cheap but considering the number of hours it takes to remove an engine, rebuild heads and all the other stuff that goes with it, I felt my time was worth it (to avoid doing this again too soon).

I bought the springs from CMS NL and the valves from Japan advertising on ebay.

http://www.ebay.com/itm/191806472708?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

They have both exhaust and intakes... when you throw in new keepers and locks/cotters, it really isn't a good economic choice but most of the time keeping an old bike alive is an expensive endeavor anyway.

 

Link to the valve tips on my 37K engine (grey and pitted single photo) and my 3K engine (bronzed and one valve tip slighly deformed).
https://goo.gl/photos/vAfdGLEVE2MmphU26

 

Only one valve on your 37k engine looks that way? I guess maybe it just goes to show you, the damage to valve tips starts happening very early and eventually leads to enough deformation in the tip that the tips break or the cotters let loose and it's goodbye to your engine. With some of the valves staying intact and others suffering heavy damage, you have to think that maybe it's a design flaw in that lubrication doesn't distribute evenly enough to all the valves or maybe there are extra hot spots on the heads due to cooling flaws or both. Extra hot spots could also contribute to diminished lubrication and also heat soaked springs becoming extra bouncy. Just thoughts on what it could be...all this on top of poorly adjusted valves, the possibilities are numerous.

 

No, they all look like that. Kind of pitted but not deformed. I wouldn't be too concerned about them 37,000 miles is millions and millions of impacts so bound to be some wear and tear.
It must be a combination of multiple factors. These things can rarely be attributed to one thing. Lubrication almost certainly a factor, along with heat and RPM. You name it. Numerous is right.

 

You'd probably find that any valves showing markings will not slip past the guides if you tried to remove them from the heads, i.e. you'd have to ruin the guide by forcing it through or you'd have to grind the valve tip down enough to get it out. Only two of the 16 valves I just replaced on my 86 came out without having to grind down the tips at least a bit. I didn't mind ruining the tips because I was not going to reuse them.

 

If nobody else, I thought you might find this a bit interesting. I was looking closely at one of my 86 spare heads from an engine I think had about 19k miles, not sure though. Notice the left exhaust valve tips on the front head are heavily damaged and all the other valves are in relatively good shape. What do those two have in common besides being on the exhaust side? The head gasket hole pattern is the same on that side for both. The holes in the head are the same on both sides but as you know, the head gasket only allows flow through the patterned holes. Perhaps that's a design flaw for the coolant flow through the heads that only shows up after a few thousand miles?

here's what I'm talking about, I have two other spare front heads I'll be checking for the same thing and let you know if they have the same condition...
last one is a set of 86 heads I just saw on ebay...LEFT FRONT EXHAUST valve....hmmmmm

 

Could be. I don't have enough evidence to see if there is kind of pattern. The only thing I used to be able to say with any confidence was that it would be an exhaust valve that would drop but you have shown even that isn't true. In a water cooled engine I would not expect huge temperature variations around the head. Aluminium is a fabulous conductor of heat so while it might get a few degrees hotter I wouldn't have thought that would be a major factor. More likely a ham fisted mechanic left the clearances too large as that is one of the fiddly locations if memory serves.

 

With the radiator removed, I actually think the front exhaust are the easiest but that's just me. It'll be something I'll keep an eye on with my future valve adjusting endeavors.

 

Something I have noticed is the number of camshafts for sale on Ebay seems very heavily biased to 84/85 engines. Far less 86. Maybe this is indicative of the number of bikes sold but it might also suggest that the 86 changes did improve longevity. Just speculation. And while we are speculating, there are not as many UK/European owners reporting valve drops to my knowledge. Not saying it doesn't happen, sure it does, but it doesn't seem as common in the years I have been following the various forums. Most engines suffering this seem to hail from the US. I think the half faired US type bike was sold in mainland Europe, but certainly the UK only got the F2 fully faired version. The fairing has additional scoops on the side and I am sure I read somewhere these were critical to channel air into the radiator. Of course the crappy weather we get probably helps too, but maybe the F2 bike does receive more efficient cooling and hence better life.

 

That's all solid reasoning/speculation. Probably many more were sold in the US compared to Europe but I don't have any data in that regard. It does seem very common to US owners to be concerned with high operating temperatures and sure, we have some very warm areas during the summer. Our gasoline quality is very bad, high ethanol content is very difficult if not impossible to avoid. I'm sure the changes to the 86 which included, bigger water pipes, bigger thermostat housing, bigger oil pump, bigger oil pan, bigger oil bolts, revised cam profile, different intake valves and springs along with wider heads for the revised cam caps, as well different fuel to carb delivery all helped but did not solve the valve dropping problems. 8000 mile oil change intervals, if followed according the owner's manual were probably a good death sentence to boot. That and carbs that easily clog and are so difficult to remove and install...etc. etc, etc... it's really kind of a miracle any of us still ride these things.