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How To Fix Motorcycle Engine Pre-Detonation

Written by Charleen

 

How To Fix Motorcycle Engine Knock

Your bike can automatically detune its engine, but there’s an easy fix.

_by Eddie Hilgendorfen |May 10, 2023

Many modern motorcycles are designed to compensate for low-octane gasoline in an attempt to prevent motorcycle engine knocking. Unfortunately, the technology involved may also cause reduced performance, rough idle or lack of throttle response, making for a less than stellar ride experience. Fortunately, we can help you understand the root cause of this problem, and offer an inexpensive, quick and easy solution.

What is engine knocking?

Engine knock  or pre-detonation is caused by an improper detonation within the engine, which happens when fuel ignites outside of a timed ignition from the spark plug. In the race to improve fuel economy, modern high-performance engines have increased compression ratios, which also inherently increases the chance of pre-ignition detonation.

Octane measures gasoline performance against pre-ignition, detonation and the resulting engine knocking or pinging. The three most common octane ratings are:

  • Anti-Knock Index (AKI)
    The rating typically displayed on North American gas station pumps as the average of the fuel’s RON and MON octane ratings (R+M)/2.
  • Research Octane Number (RON)
    This rating is determined by testing fuel using a variable compression ratio under controlled conditions and is the most common industry rating worldwide. When comparing octane ratings, RON is typically higher than the AKI number, so an 87-octane AKI fuel at a typical gas station typically has a RON of 91-92. AMSOIL uses RON when conducting product validation and performance testing.
  • Motor Octane Number (MON)
    MON differs from RON testing by using a preheated fuel mixture, variable ignition timing and a higher engine speed to increase ignition stresses on the fuel. Though the tests are unrelated, MON results are typically 8 to 12 octane lower than RON.

Causes for loss of power and efficiency

Low-octane gasoline is more susceptible to uncontrolled and early ignition in the combustion chamber, so the higher the octane, the more compression the fuel can withstand before igniting. Pre-ignition robs the engine of power, can cause a noticeable knocking or pinging sound, and if left unchecked, can even cause catastrophic piston or cylinder damage.

This is why I decelerate (turning off the cruise control) when driving up or climbing steep hills and I also sometimes turn off the air conditioning. Also doing this you can see A decent increase in your fuel efficiency

High stress combined with lightweight design caused this dirt bike piston to fail. Dude was in first place so missed out on the cash prize.

Reduced performance.

Many modern motorcycle engines are equipped with a knock sensor. Pre-Detonation causes this sensor to adjust timing to compensating for low-octane gasoline. Unfortunately, adjusting the timing usually results in a noticeable decrease in performance, rough idling and lack of throttle response. When timing changes are done correctly, most riders shouldn’t even be aware that the performance has been reduced, but it’s easy to resolve this performance problem.

Boosting octane To Reduce Knock

The risk of engine knock can be reduced by:

  • retarding ignition timing
  • enriching the air-fuel ratio
  • reducing cylinder pressure or engine load
  • reducing the throttle or boost especially as you climb a hill
  • increasing the octane rating of the fuel
  • Engine work – lower compression

Therefore, the performance degradation caused by reduced engine timing can most easily be eliminated by increasing the fuel’s octane number. AMSOIL Motorcycle Octane Boost increases octane up to three numbers. On a bike that can be significant! This helps to eliminate motorcycle engine knocking and maximize power, performance and fuel efficiency. We get a LOT of feedback on this. Check out the product reviews.

 

 

 

 

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Don’t Let Extreme Heat Sideline Your Motorcycle

Written by Charleen

An Oil to Resist Thinning from Extreme Heat and Mechanical Activity

Extreme summer heat combined with slow-moving rally or parade traffic can pose big problems for you and your motorcycle.

As heat intensifies, motor oil loses viscosity and becomes thinner. The oil can become so thin that the engine loses oil pressure, causing the oil-pressure gauge to bottom out. You may hear increased valvetrain and gear noise as parts clatter together. A good rider knows not to ride with no oil pressure, so he or she will shut down the bike and sit alongside the highway (or push the bike) until the engine cools enough to restore oil pressure.

Decreased airflow stresses oil

Air-cooled V-twins get plenty hot on their own, but riding in slow moving traffic makes it worse. Crawling along barely above idle doesn’t generate enough airflow to cool the engine. Add to that the blazing sun reflecting off the asphalt, and it’s a recipe for trouble. In extreme dyno testing designed to create heat, we’ve seen cylinder temperatures in a 2012 Harley-Davidson* Street Bob* as high as 383°F (195°C).

It’s up to the motor oil to protect the engine despite the intense heat; however, oil becomes thinner as it heats up. If it becomes too thin, it can fail to form a lubricant film of enough thickness and strength to prevent metal components from contacting during engine operation and wearing out. Once the lubricant film fails, it falls on the anti-wear additives to prevent wear. They form a sacrificial layer on components to keep them from contacting. But additives are designed to deplete with time and use. Once they wear out, your engine isn’t protected in this scenario.

Heat breaks down oil faster

The rate at which oil oxidizes, or chemically breaks down, doubles for every 18°F (10°C) increase in lubricant temperature. Oxidation occurs when oxygen molecules attack oil molecules and result in a chemical reaction that leads to harmful byproducts, like sludge and varnish. The faster the oil oxidizes, the sooner it wears out and requires changing.

Ride Hard. Run Cool.®

AMSOIL Synthetic V-Twin Motorcycle Oil uses high-quality synthetic base oils that naturally resist thinning due to extreme heat and mechanical activity better than conventional base oils. As a result, it forms a thick, strong lubricating film on engine components despite the intense heat. Although any oil will become thinner in extreme heat, riders who use AMSOIL Synthetic V-Twin Motorcycle Oil won’t see their oil-pressure gauges bottom out, providing the confidence they need to keep riding after others have shut down their bikes and started pushing.

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*All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for use in the applications shown.

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Why You Should Be Wary About Using Break In Oil in Powersports Equipment

Written by Charleen
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Why You Should Be Wary About Using Break In Oil in Powersports Equipment

John Baker|

Marco Navarro asks on our Facebook page about break in oil, with attention paid to powersports engines.  (Break in oil importance, drain interval on it, and applications. To include motorcycles and ATVs since life of engine is shorter and rebuilding occurs more often.)
Thanks for the question, Marco.

Let’s get to it.

Maintaining an engine is a constant fight against wear. Over time, wear not only results in expensive damage, it reduces compression, robbing your engine of power.

That’s why it can be tough to accept that “controlled wear” during a new or rebuilt engine’s break in period is critical to maximizing its power and longevity.

Take a seat

One of the primary reasons to break in an engine is to seat the piston rings, and that means allowing the rings and piston skirt to carefully wear down the peaks (called asperities) on the cylinder wall.

The images show what we mean.

Although a new or freshly honed cylinder appears smooth to the naked eye, it contains microscopic peaks and valleys. If the valleys are too deep, they collect excess oil, which burns during combustion and leads to oil consumption.

The sharp peaks, meanwhile, provide insufficient area to allow the rings to seat tightly. That means highly pressurized combustion gases can blow past the rings and into the crankcase, contaminating the oil and taking potential horsepower with it.

Breaking in the engine wears the cylinder-wall asperities, providing increased surface area for the rings to seat tightly. The result is maximum compression (i.e. power) and minimum oil consumption.

Getting the shaft

That brings us to the other primary reason to break-in an engine: to season, or harden, the flat-tappet cam. Flat-tappet cams can wear out faster than their roller-cam cousins, especially in engines modified with high-tension valve springs.

And cam wear is bad. Really bad. Worn lobes or tappets affect valve lift and duration, which reduces engine power and efficiency. In extreme cases, increased pressure can remove material from the lobes and deposit it in the oil, where it circulates through the engine and causes damage. Break-in helps harden the metal so it’s more resilient to wear.

That raises a critical question: How do we simultaneously allow controlled wear to the cylinder wall/piston rings while protecting the cam against wear? Those two tasks seem mutually exclusive.

In a word, oil

The solution is to use a properly formulated break in oil that allows controlled wear at the cylinder wall/piston interface, but that also protects the cam lobes and tappets from wear.

How do we accomplish this black magic?

Most break in oils, including AMSOIL Break-In Oil, use conventional base oils. Compared to their higher-quality synthetic counterparts, conventional base oils result in a thinner, less durable protective oil film on engine parts. The thinner fluid film allows controlled wear at the cylinder wall/ring interface.

But what about the cam? Won’t it wear, too?

ZDDP

That’s where anti-wear additives come into play. ZDDP anti-wear additives are heat-activated, meaning they provide wear protection in areas of increased friction. In this case, it’s at the cam lobe/tappet interface. The additives form a sacrificial layer on the surface of parts, which absorbs contact and helps prevent cam and tappet wear.

As a rule of thumb, a good break in oil should be formulated with at least 1,000 ppm ZDDP. At AMSOIL, we take it a few steps further; our Break-In Oil contains 2,200 ppm zinc and 2,000 ppm phosphorus.

How long does break in require?

Another rule of thumb states you should season a flat-tappet cam by running the engine above 2,500 rpm for 15 minutes.

As for seating the rings, our testing has shown it can take as little as seven dyno passes. That time varies depending on the engine, ring tension, cylinder hone and other factors.

If you don’t have access to a dyno, follow the engine builder’s or manufacturer’s recommendations. If none are provided, consult the recommendations on the break in oil label. In general, run the engine under light-to-moderate loads for about 500 miles. Again, that duration is a rule of thumb, but break in shouldn’t exceed 1,000 miles. Then, drain the break-in oil, install the synthetic oil of your choice and commence driving.

An engine dyno provides the best method of determining exactly when the rings are seated. You’ll notice a boost in horsepower as the rings seat. Eventually, horsepower will stabilize once the rings are seated.

Check out 5 Ways to Boost Horsepower for Under $500

You can also perform a leak-down test. Another, albeit more time-consuming, method is to remove the exhaust headers and check for oil residue in the exhaust ports. Presence of oil shows the engine burning oil, meaning the rings aren’t completely seated. Once the oil residue is gone, the rings are seated.

What about powersports engines?

Ask yourself a few questions about your motorcycle, ATV or other powersports application before using a break in oil:

  1. Does it have a wet clutch? If so, the break in oil may not be formulated for wet-clutch compatibility, leading to reduced performance.
  2. Does it use a shared sump with the transmission? Many motorcycles use one oil to lubricate the engine, transmission and primary chaincase. The churning action of transmission gears, especially in high-rpm applications, can tear apart – or shear – the oil if it’s not formulated to handle the stress. Using a break in oil not designed to handle high-shear applications can lead to damage.
  3. Does it have a dry sump? Some motorcycles store motor oil in a tank separate from the engine. Residual break in oil can collect in the system following the break in period and contaminate the service-fill oil. In this case, run the engine long enough to circulate the oil throughout the system and change it a second time to ensure the break in oil is completely removed.

Given the above challenges, we recommend breaking in a rebuilt powersports engine using the motor oil you’ve always used. Run it according to the original equipment manufacturer’s (OEM) new-engine recommendation, then change the oil. In short, treat it like a new engine from the factory.

For new engines, just follow the OEM guidelines. Typically they recommend a shorter interval for the first oil change to remove wear particles and contaminants from the factory. Then, change to the AMSOIL synthetic motor oil that’s recommended for your application and commence riding.

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Should I Warm Up My Motorcycle Before Riding?

Written by Charleen
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Should I Warm Up My Motorcycle Before Riding?

John Baker|

As soon as you crawl out of bed tomorrow morning, try this experiment: run outside and sprint down the street. Aside from embarrassment over your jammies (or lack thereof), how do you suppose you’ll feel?

Your motorcycle likewise needs to warm up a bit before hitting the street. Many folks at AMSOIL love anything to do with an engine, including motorcycles. So to get the technical details explaining why, I consulted a few of our resident bikers. They provided two main reasons for letting your bike warm up before riding.

1) Help avoid piston scuffing

Metal expands when it’s heated, and anyone who’s sat astride a motorcycle knows they make serious heat. Subjecting a cold piston to extreme heat and friction without first allowing it to warm up can cause rapid piston expansion and scuffing.

John Skuzinski, AMSOIL Mechanical Test Development Manager, says this:

“Optimal parts ??clearances inside the engine are not achieved until normal operating temperatures are reached. If clearances are less than normal due to low engine temps, and the throttle demands the engine goes to work spontaneously, internal temperatures can rise very rapidly. Most frequently the pistons will heat-up and expand well ahead of the cylinder bores. The chances of clearance-related scuffing and seizure are thereby increased proportionally.”

Translation? Something might break.

AMSOIL Director of Facilities and Maintenance, Rollie Everson, agrees. “I like to get them [engines] warm before putting any type of stress on the mechanical components. This makes sure components expand at a gradual rate when they are cold.”

2) Ensure the oil circulates properly

Another reason to warm up your bike is to circulate the oil. Here again John Skuzinski has some good insight. “Cold oils inhibit pumpability and flowability, making it more prone to thin-film and hydrodynamic-wedge breakdown. Under extreme cold-oil conditions, it is possible that the oil won’t be able to flow into the oil pump, leading to bearing and journal damage and wear.”

Translation? Again, something might break, this time due to lack of oil.

Of course, a good solution to poor cold-flow is to use a high-quality synthetic that flows quickly to engine parts despite cold temperatures. AMSOIL laboratory chemist Dale Beck explains:

“The highest chance of wear should be under the initial startup when the oil has yet to be circulated to all the components in the upper end. AMSOIL motorcycle oils have very good pumpability at cold tempatures, definitely colder than I enjoy riding the bike at, so I don’t worry much about the oil not being circulated enough. Our oils also have very good protection for cam wear, relating to initial startup, so unless you are redlining the engine after startup there shouldn’t be any worries about other engine parts.”

How long should you warm the engine?

About one minute is plenty of time to allow the piston and other parts to gradually expand and ensure good oil circulation to the upper end. Most riders start the engine and spend a minute or two putting on their helmet and preparing to ride. Once they’re ready, so is the bike.

“I warm mine up so I know everything is running well. I usually do this while I put on my helmet and make final adjustments before departing on a ride.” – Patricia Stoll, AMSOIL Trade Show Manager

“I usually let it warm up while making my last adjustments (ear plugs, gloves, glasses, etc.). This takes about a minute or two.” – Jim Swanson, AMSOIL Trade Show Representative

“I would guess that mine only warms up for around a minute. I usually start it just before putting on my helmet and gloves. In my opinion, anything more than a few minutes is a waste of fuel and can lead to deposit formation on the spark plugs and exhaust.” – Dale Beck

To wrap it up, warm up your bike for at least a minute before heading out. Just use the time to buckle your helmet, slip your gloves on or finish other preparations. That way you’re not wasting time – and you’re likely saving your engine from wear.

Find out why our Co-President & CFO loves V-twins.

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