Gaskets n' things: Curing the no-more-parts-for-the-VF500F plight

Is the premature wear of the valve stem ends (mushrooming as noted in Service Bulletin No. 7) also a cause of valves dropping on these engines?

 

I hate to say it, but the actual mileage is unknown. When I bought the bike, I was told that the gauge cluster had been replaced two owners previous, and the mileage wasn't recorded. So, on my title, it's mileage is 999,999.
Likewise, the maintenance history is unknown. The PO told me he was a "hop on and ride", and didn't bother with investigative maintenance. Another bummer (and what should have been a red flag).
When I took my bike to get tuned up by my mechanic, he did everything but the valves. However, the tune up, including cleaning carbs, came to $600. He told me that 1), the valves would take him at least another 4 or 5 hours, and 2) he was wary to take the valve covers off, because his employer/ parts source didn't have the gaskets.

Yes, I know, I was irresponsible. I'm disappointed in myself, but then again, these things happen sometimes, whether or not we are prepared for them or not. So it goes.

I will absolutely let you know what I find out when I drop the engine and take the heads off.

 

To clairfy (and save face): While I did twist my baby's neck on occasion, to pass, etc, I never redlined. The highest I think it ever got was 11k, and that was trying to get onto 93 with very fast-moving traffic. I went relatively easy on the girl, 10k was as high as it ever went on the day-to-day

 

It is a bit of a tough go as the tech working on the tuneup stopped short of removing the cam covers and inspecting the valve train. Often the rubber cam cover gaskets can be reused but parts are getting scarce so I can understand the tech's concern about going a bridge too far.

I'll be curious to see what you discover when you remove the covers and then the heads.

 

Negative. The mushrooming is not from wear but rather from damage due to the slide-hammer effect of floating valves. The SB for the caps was a stop gap by Honda to try and put a Band-Aid on the problem. Obviously it didn't work as many with the caps still dropped valves.

Bottom line - dropped valves is the cause of one single factor, and that is valve float.

 

Makes sense, thank you for the post.

Is the way to prevent valve float (albeit this is somewhat expensive as has been posted) to install new KPMI springs, valves and retainers - or - would you be okay installing KPMI springs w/ the stock valves and retainers?

 

Are you sure that Kibblewhite has a set of VF500F valve springs?

That's the culprit - replacing just the spring is the only thing you need. However, an aftermarket set of springs may require special matching retainers. Keep that in mind because it would significantly increase the cost.

 

I don't blame him at all. Plus, he does all the work out of his garage in his free time. By day, he's a mechanic. By night... he's a mechanic.

 

Yes, they said that they do - though they did request that I send them a spare head so they can use this for reference.

Not having to change the valves and retainers is be a big plus. The costs are pretty steep so if it is only the springs that are required, this is great news.

 

http://vfrworld.com/forums/1st-2nd-generation-1983-1989/28596-vf500f-valves-3.html#post272236

If we could get enough of us to be interested, and financially able at the same time, it sounds like a group buy would be a good idea.

 

This is definitely something to consider...though the '86 owners have a different animal (different part numbers for the valve springs) so our buying power is somewhat based on the model year.

'84/'85
inner spring 14761-KE8-003, outer spring 14751-KE8-003

'86
inner spring 14761-MF2-711, outer spring 14751-MF2-711

I did write to Dave Dodge awhile back regarding rebuilding a set of heads for me (I have an '84) and he wrote something interesting regarding the '86 heads:

"...we backdated the valves and valve spring pressure on 1986 model heads. This took some stress off the valves and retainers to prevent valve dropping common the the '86."

It is well documented that the '84/'85 and '86 all suffer from a valve float malady but perhaps the 'early' springs are a good option for '86 owners as well. This would help increase the market.

I purchased a used set of '85 heads and have the UPS shipment of these to KPMI on the clipboard - perhaps later this year. This should help answer a few questions about what all is required to upgrade the valve springs...

 

I'd be curious to hear what they said after they had a chance to check it over.

 

5x5, I will post an update if/when I send to KPMI.

I have also been corresponding with a Factory tech who worked on VF engines back in the day. He owns, since purchased new, an '83 VF750 (along with a VFR800). He is very complimentary of V4 engines, though he is well aware of the VF's wear issues.

To help with this, he offers a performance coating for the cam and rocker contact surfaces which helps reduce wear.

I mentioned about the VF500F's valve float malady and my thoughts on upgrading the inner and outer valve springs. He mentioned that he is somewhat hesitant to install performance springs on an otherwise stock engine. His reasoning is that stiffer springs can lead to additional cam and rocker wear.

He said both valve springs and binding valve stems can be culprits when it comes to valve float.

His recommendation is to coat the cams, rockers and valve stems, to change the oil every 1,000 to 2,000 miles and to provide additional valve clearance (lash) to help eliminate binding at the cam apex.

I am thinking about sending my '85 set of heads to him for a close inspection and if all looks okay I will add the coating. I will post an new thread with additional intel...

 

Interesting. Keep us posted.

 

While it's true that a valve spring design which would correct the valve float issue would result in higher contact stresses, there really isn't any other way to fix the problem. His comment about binding valve stems is a new one to me - and it sounds kind of far fetched considering that those engines don't show any of the other signs of this happening (preamture guide wear).

I've tried coatings on the cams and rockers of the early V4's with poor results. Applied coatings don't like high contact stresses, they prefer sliding wear surfaces like fork tubes. The best that I cam up with was an Ion Nitride process that is not a coating but more like a heat treatment process. Very pricey. If you correct the oil supply to the heads I don't think you would have any trouble running improved valve springs.

 

Thank you for the post. The Ion Nitride process sounds interesting. I will check in with the tech on the type of process he uses.

In terms of improving the oil supply to the heads - I had checked with Dave Dodge awhile back and he wrote that he felt a top end oiling kit wasn't a good option on the 500.

Is a top end oiling kit still on the table?

 

I think by his own admission Dave does not have much experience with the 500's. I can tell you that it's been proven the 500's also suffer from rocker arm wear due to inadequate oil supply - just like the larger engines. It's not normally considered a big enough issue to do something about because dropped valves dominates the engine failures on the 500's. In the context of this discussion it's pertinent to identify the oil supply as something to be upgraded along with the valve springs.

Before we got off in the weeds too far, let's not forget that a valve spring design that corrects the valve float on the 500's will not necessarily have a large increase in spring force. Since brand new OEM Honda springs were ok for a while, it suggests to me that a small increment in force will do the job. I'm still in the design stages of a set of VF500 valve springs so I don't know for sure yet what spring forces will be required. It's a little early to think that a good set of springs would cause the rocker arms to wear any more than already exists.

 

I tend to agree with Jamie on this one. I'm not thinking that the springs will need to be much stronger than the originals. I remember reading about Japanese springs being questionable around the time of the 1st gens, meaning they probably became weak early on, and new springs would be moer on par with replacing the stock springs with higher quality replacements, not necessarily much stronger springs.

 

Valve springs can and will sack out from heat and stress, praticularly older designs. I have used RD springs in XR and CB engines with good results, seat pressure in some cases is actually less than OEM. I looked at the RD website and did not see listings for VFs, but it might be worthwhile to contact RD.

R/D Valve Springs - Quality Isn’ Expensive, it’s priceless!

 

I did contact R/D awhile back.

They are happy to provide springs (they once offered a VTR250 kit as did KPMI). R/D did request sending a spare set of heads for reference. KPMI basically said the same thing.

I am sure both companies would do an excellent job.