The Benefits Of Running Steel Valves In A Four-Stroke Engine

Steel valves versus titanium valves with Wiseco’s Dave Sulecki

Steel Valves on white background.
When comparing valve material for four-stroke engines, steel is a lower-cost alternative to titanium.Courtesy of Wiseco

One of the basic truths of the imperfect world we live in is that the people who design machines are not the same people who have to maintain those machines. This often leads to situations where something that seemed like the way to go on the CAD screen turns out to be more difficult or more expensive to fix in the real world than it otherwise would be. Exotic materials and painstaking processes that are economical to implement when you’re mass-producing something turn out to be expensive to service in the field.

In this single-serving, throw-it-away-when-it-breaks world, there are some noble souls who take a stand and say that, instead of discarding them, we should be able to service and maintain things ourselves, bringing new life to machines that need a bit of a refresh.

When faced with the price tag on factory replacement parts for bikes that came with trick valve train components, many owners cringe at the price of refurbishing a tired engine. However, with the right components at the right price, turning around your dirt bike’s midlife crisis and letting it catch its second wind can be easy.

Win On Sunday, Sell On Monday

Nobody wants to buy a new bike that has a whiff of “outdated” technology surrounding it, so a lot of the high-end features that really only make a difference to the top 1 percent of professional racers become must-haves for weekend warriors who just want to trail ride with their kids. When those parts wear out, the exotic bragging rights come with a cost though.

“Titanium is a great valve material due to the strength-to-weight ratio, and also the material’s ability to deal with the high temperature of combustion,” Wiseco Product Manager Dave Sulecki says. “The light weight is important for engine acceleration; imagine how a heavy component takes more energy to move, and you can see where titanium is ideal when the camshaft needs to accelerate the valve quickly with less energy, and you can see that a lightweight component would be critical for a high-end racing engine.”

Steel Valves on white background.
Steel valves are slightly heavier than titanium valves.Courtesy of Wiseco

While those race-spec valves come standard because they’re a positive selling point on the dealership floor, they’re mostly there for bragging rights instead of making a difference you’ll feel when twisting the throttle yourself, and it’s cheaper for the manufacturer to make everything to one specification than it is to have separate designs.

“This light weight and performance comes at a greater cost,” Sulecki continued. “The material is more expensive, and costs more to machine or form into a valve. Additionally, the titanium requires a special coating to deal with the heat and wear, which also adds cost. This expense is needed for the highest-performing engines, like the type you find in nearly all levels of racing from motocross to Formula 1.”

Sticker Shock

Even expensive, exotic materials wear out though, and when it’s time to freshen up the valve train of your bike, you might be surprised to see just how much it will cost to replace like-for-like with factory components.

“Steel valves are a great low-cost alternative to titanium,” Sulecki explains. “[They] offer longevity, reliability, and improved wear over titanium. Some customers are not always racing their vehicles, and just want longer service intervals and the peace of mind that comes with this material.”

Steel valves are designed to be an affordable way to refresh your high-tech dirt bike’s valve train. Although they may not be made from titanium, that doesn’t mean they aren’t precision-engineered.

“Because steel valves are a small percentage heavier than titanium valves, heavier-rate valve springs are required to control the valve and protect the engine from valve float (the condition where the heavier valve will stay open under high-rpm engine speeds),” Sulecki added.

Steel Valves on white background.
According to Wiseco Product Manager Dave Sulecki, because steel valves are a small percentage heavier than titanium valves, heavier-rate valve springs are required to control the valve and protect the engine from valve float (the condition where the heavier valve will stay open under high-rpm engine speeds).Courtesy of Wiseco

Time For A Change

So how do you know when it’s time to replace the stock components, short of a dropped valve or broken spring?

“Valves and valve springs wear over time, like any highly stressed engine component,” Sulecki says. “When you are checking the valve clearance, or making shim adjustments, this is always a good indicator of how quickly the valves are wearing or receding into the seat.”

Keeping an eye on these telltales during your regular maintenance will allow you to judge when your factory valves and springs are reaching the end of their service life.

“When you are inspecting your top end for general overall health, such as the piston and ring condition, this is the best time to take a closer look at the valves and valve springs,” he continues. “Valves and springs need to be removed from the cylinder head for full inspection. Once they are removed, you can look closely at the condition of the valve face where it seals to the valve seat, and also the condition of the valve head overall and the stem condition. Any cupping or damage to the valve face means it is time to replace the valve, and any similar wear to the valve seat means replacement or recutting will be needed.”

Over time, springs become less elastic and may no longer be able to control valve motion at high speeds, but it’s not the sort of wear that is immediately obvious to the naked eye. Any nicks or cracks are a sure sign of impending doom, and your cue to replace the entire set.

“Valve springs should be inspected for free length, and also overall condition, looking for any wear marks or defects that can lead to spring failure,” Sulecki says.

Wiseco Steel Valves on white background.
Steel valves can be purchased on the aftermarket from companies like Wiseco, which offers its Garage Buddy Steel Valve Kit that includes steel valves and heavier-rate valve springs.Courtesy of Wiseco

Doing The Job Right

Depending on your level of mechanical aptitude and how well-equipped your garage is, valve replacement might be a job you want to subcontract to a professional.

“For most all valve replacements, it is a good idea to work with a qualified builder if you are not sure about the condition of any of these components,” Sulecki suggests. “The work can be done in your own workshop, but there are some special tools required to remove the valves from the head, and having an experienced eye on these items is always the best approach if you are not sure what to look for. An OEM service manual is always the best place to start as they will provide information about any special tools, and guidelines of what to look for regarding valves, valve seats, and even valve guides and their condition.”

Whether tackling the job yourself or letting a professional handle your top end maintenance, you’ll save time and money by seeing to all the wear-prone components at the same time.

“When replacing valves, it’s a good idea to inspect the top end for any concerning issues or conditions,” Sulecki says. “Inspect the valve seals, valve keepers and seats, shim buckets, the condition of the cylinder head (flatness and sealing condition), and cam-chain condition.”