Video is good here.
I wonder if there are similar issues with other Vstar bikes that run two valves off one lifter or cam?
I think the Royal Star V4 and the Road Star engines are both designed this way.
Most people use aftermarket oils, most of those oils have enough ZDDP in them, it is the new oils where a problem can pop up because some of the oils are only 600 ppm of ZDDP.
The V-4 engines were/are overhead camshaft engines, they don't need high valve spring pressures so those engines would not need the higher levels of ZDDP.
Overhead cam engines, overhead cam with follower engines and engines that use roller cam/lifters do not produce the pressure upon the cam lobe that a flat tappet solid lifter or hydraulic lifter does. Where I think an issue can come into play on the 1854 cc V-Twin is because it uses one cam lobe, one lifter, one pushrod and one rocker arm to activate two valves and valve springs at once, you are no longer equivalent to an OEM low pressure valve spring because you are activating two valves and valves springs at once, so you have to overcome the pressure of two OEM valve springs instead of one.
Now the service manual does not list how strong the pressure is of the OEM valve springs but lets just say they are 45 pounds each, you have a pushrod on one side of the rocker arm activating two valves/valve springs on the other side of the rocker arm so you can see how the OEM spring pressure is not 45 pounds but is much higher and entering the area of a high performance valve spring.
One thing that is a known is flat tappet engines like ZDDP, it is an anti wear extreme pressure additive that coats the cam lobe and lifter as well as other parts in the engine/primary/transmission and it has proven to make a flat tappet style cam and lifter survive the pressures placed upon them. The ZDDP sacrifices itself during start up keeping the cam lobe and lifter from being metal on metal.
A lot of people got caught off guard when the oil companies reduced the amount of ZDDP in oils and many cam lobes and lifters were destroyed because of that. Now that it is known people take precautions to avoid the problem and cam shaft failure is far less likely today.
We have a known anti wear extreme pressure additive in ZDDP that we know works with flat tappet cams so in my opinion it is just smart to make sure you have an oil with a high level of ZDDP in it because of the flat tappet style cam and lifter Yamaha choose to use in the 1854 cc V-Twin engines. This becomes even more important for those who like to push their engines, now this engine redlines at only 4,750 RPM's so you are not placing the same amount of wear on the cam lobe/lifter as a flat tappet engine that redlines at 7,000 or 10,000 RPM's.
The low revving of this engine contributes to keep wear down but again due to it being a four valve per cylinder engine it is the added pressure of activating that second valve/valve spring that I believe can be a problem with these new oils and their reduced ZDDP content.
Where the wear is going to be most critical is at start up as the new oils anti wear extreme pressure additives don't coat the cam and lifer like ZDDP does.
Also ZDDP is an anti wear extreme pressure additive that gets used up as you put miles on the oil, so if you are right at the limit for protection with a fresh oil change once you get to 4,000 miles out on that same oil you are now below the minimum protection level that ZDDP provides because it is used up over the miles.
One shop several years ago that uses Roush Racing engines suddenly started wearing out cam lobes and lifters on the engine dyno, they could not figure out what was going on as they could not get the cam and lifter to survive just the dyno run. Roush was sponsored by Valvoline at the time and that was the oil that was being used, well after much investigation what they found was Valvoline had changed the formula of the oil and had reduced the amount of ZDDP in it and being a high performance engine it would eat up the cam lobes and lifters in no time at all on the engine dyno. Valvoline worked with Roush Racing and they redid the formula adding back the ZDDP and the problem was solved.
Myself I follow one engine shops advice of running no less than 1500 ppm of ZDDP that way as the oil gets miles on it and the ZDDP is being used up there is always adequate ZDDP available to protect the flat tappet cam and lifters. For me it is a cheap insurance policy.
Depending on what engine builder you research you will get a recommendation from 1200 ppm ZDDP to 1500 ppm ZDDP, as I said I follow the shop that recommends 1500 ppm ZDDP and I have not had any issues to date. I currently have 12,982 miles on my engine.