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Hello, all,

Reviving my '92 ZX-11 C3 after 15 years of dry storage. Relatively low mileage bike: ~14,000 miles. Some of the valves wouldn't fully close so I've pulled
the head off and removed the valves. Performed some very mild clean-up of the ports (blending the valve seat and the port where needed, removed a
casting lip at the exhaust end of the exhaust ports, lightly smoothed the angles left by factory milling of the port runners, etc).

Valve seats and valve faces look new but I will leak check them before reassembly. I really don't want to lap them unless necessary. I've found nothing
fine enough not to risk gougeing up these surfaces.

Question: the factory manual says to lubricate the valve stems with molybdenum sulfide-bearing grease. I understand that (extreme pressure additive) but
nothing is said about viscosity, base (calcium vs. lithium), drop-point temperature, synthetic vs. traditional. I suspect chassis grease (with graphite and moly)
might not hold up to the temperatures involve. I don't want to leave clay or whatnot in the the valve guides if and when the grease wears out.

So, I'm asking for recommendations for most suitable moly-bearing grease for lubricating valve stems during assembly and subsequent running.

Thanks in advance. Hope all of you are well.

H.
 

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I've asked about the molybdenum disulfide thing at a few shops and workplaces over the years. Most of the time it gets a small chuckle. Common consensus is use a high quality engine assembly lube and forget about it.

All the grease will eventually get washed away by oil. It's only job is to keep stuff from running dry until the oil gets there. Sounds like an identical job to assembly lube to me.

Personally, I've used the permatex stuff on about 20 rebuilds. Mostly high revving Kawi inline 4's but also some single cylinder dirt scooters of the 2 and 4 stroke variety. Never had even the slightest hint of trouble.
AssemblyLube.jpg
 

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Hello, all,

Reviving my '92 ZX-11 C3 after 15 years of dry storage. Relatively low mileage bike: ~14,000 miles. Some of the valves wouldn't fully close so I've pulled
the head off and removed the valves. Performed some very mild clean-up of the ports (blending the valve seat and the port where needed, removed a
casting lip at the exhaust end of the exhaust ports, lightly smoothed the angles left by factory milling of the port runners, etc).

Valve seats and valve faces look new but I will leak check them before reassembly. I really don't want to lap them unless necessary. I've found nothing
fine enough not to risk gougeing up these surfaces.

Question: the factory manual says to lubricate the valve stems with molybdenum sulfide-bearing grease. I understand that (extreme pressure additive) but
nothing is said about viscosity, base (calcium vs. lithium), drop-point temperature, synthetic vs. traditional. I suspect chassis grease (with graphite and moly)
might not hold up to the temperatures involve. I don't want to leave clay or whatnot in the the valve guides if and when the grease wears out.

So, I'm asking for recommendations for most suitable moly-bearing grease for lubricating valve stems during assembly and subsequent running.

Thanks in advance. Hope all of you are well.

H.
Replace the valve seals and lap with fine grit. Lube with a low solid petroleum based grease. Put it back on.
 

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