McCulloch BP-1 Chainsaw with Rare Twin-Piston Balancing Engine

The McCulloch BP-1 is a legendary model among vintage chainsaw enthusiasts. Produced only briefly from 1962 to 1963, this saw packed innovation that was well ahead of its era.

At first glance, it looks like a typical 1960s one-man chainsaw in McCulloch’s iconic yellow, but inside it hides a radical engineering concept. Friendly and unassuming as it may appear, the BP-1 has a story that combines cutting-edge design, a bit of mystery, and a whole lot of collector intrigue.

The BP-1 featured in this article belongs to New Zealander Tim Hunt.

The “BP” in BP-1 stands for Balanced Piston, and this saw remains the world’s only chainsaw to use a twin-piston balancing engine.

Unlike a conventional single-cylinder two-stroke, the BP-1’s engine had two pistons in one cylinder – one piston provided power, while the second acted as a balance weight and even served as a sliding intake valve.

This clever dual-piston design canceled out vibrations and allowed the engine to breathe efficiently at high RPMs. In fact, the little 44 cc engine produced about 4.2 horsepower at 10,000 RPM – an astonishing speed for the early 1960s. At a time when most chainsaws ran around 7,000 RPM, the BP-1 was screaming along at up to 12,000 RPM (governed) in stock form.

Mike Acres’ site states:

Worlds only Balanced Piston engine chain saw. The BP-1 is a high speed engine utilizing one piston for power and one for balance and as a sliding intake valve.

This saw was sold for a very short period of time and then withdrawn from the market by McCulloch. Because of the RPM that the engine was capable of if the governor failed it was feared that the flywheel would disintegrate and injure the operator.

It even featured other advanced touches like a die-cast magnesium body and McCulloch’s Auto-Mac chain (with a built-in sharpener) to keep the cutting chain keen in the field. By all accounts, the BP-1 was a bold leap forward – some say 20 years ahead of its time in chainsaw design

So, if the BP-1 was so advanced, why don’t we see more of them?

The answer lies in its historical context and a bit of bad luck. McCulloch introduced the BP-1 in September 1962 as an experiment in high-performance, low-vibration chainsaws. However, running on the ragged edge of technology had its risks. There were serious concerns that if the mechanical governor failed, the engine could over-rev – potentially causing the flywheel to explode apart at those extreme speeds.

In other words, the very power that made the BP-1 special also made it a safety hazard. McCulloch responded by withdrawing the model from the market after only about a year. In fact, the company reportedly recalled all BP-1 units and destroyed those returned, rather than risk catastrophic failures in the field. As a result, only a few saws escaped the recall (likely kept by owners who didn’t turn them in) – and those survivors are now extremely rare.

On the Vintage Chainsaw blog, there is the note:

The BP-1 chainsaw was decades ahead of its time. It featured a dual-piston design that balanced the engine and improved porting efficiency.

The saw could run wide open at 12,000 RPM, but a failure in the governor assembly could cause the engine to over-rev, potentially bursting and injuring the operator.

As a result, McCulloch recalled and destroyed nearly all of them. Only a few survived, making this an exceptionally rare saw today.

Because of its brief production and recall saga, the BP-1 has taken on an almost mythical status among chainsaw collectors. Even in its own time, not many loggers ever saw one.

Today, finding a BP-1 “in the wild” is like striking gold. Collectors love the mystique and backstory as much as the machine itself. After all, this saw was an engineering marvel that was too advanced for its own good, and that kind of story fuels a lot of fascination. The BP-1’s uniqueness and scarcity mean that it’s highly sought-after – a true centerpiece for any vintage chainsaw collection.

All this hype begs the question: what is a McCulloch BP-1 actually worth today? Prices can vary, but expect to pay a premium for this rare saw.

A decade ago, collectors noted that a decent running BP-1 would typically fetch between $400 and $600 depending on condition. If you were lucky enough to find one in mint, museum-quality shape, it might reach around $1,000 or more. In recent years, as these saws have only gotten scarcer, some sales have pushed even higher.

For example, one especially clean BP-1 sold at auction for about $1,500, though another, less pristine example went for around $500 shortly after. Timing and condition are everything – the first BP-1 to pop up after a long dry spell can fetch a big price, whereas the next one might go a bit lower.

There are even instances of sellers asking north of $2,000 for a fully restored BP-1, reflecting its “holy grail” status among McCulloch fans.

Of course, true collectors will tell you it’s not just about the money. The BP-1 is a prized collectible because of what it represents: a bold technological leap, a rare survivor of a recalled experiment, and a proud piece of McCulloch’s legacy.

Its value is as much historical and sentimental as it is monetary. If you’re ever fortunate enough to find a BP-1 (perhaps lurking in an old barn or shed), you’ll have discovered a real gem. Just be prepared for some envy from fellow collectors!

The McCulloch BP-1 may not have cut timber for very long in its day, but it certainly carved out a special place in chainsaw history. With its one-of-a-kind balanced piston engine and high-revving performance, the BP-1 showed what was possible when engineers pushed the envelope – and it left us with a fantastic story to tell.

Today, it stands as a collector’s treasure, beloved for its uniqueness, its rarity, and the window it provides into a time when chainsaw makers weren’t afraid to try something completely new. For chainsaw enthusiasts, the BP-1 isn’t just an old tool – it’s a conversation piece, a technical wonder, and a reminder that even in the woods, innovation sometimes blazes ahead of its time.

Whether you’re lucky enough to own one or simply admire them, the BP-1’s friendly roar and fascinating backstory continue to engage and inspire the chainsaw community.