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Using a new technology to investigate an old motorcycle

Casting, forging and heat-treating parts, brazing the frames and bolting their machines together, the Depression-era craftsmen who built Harley-Davidson motorcycles were masters of yesterday’s technology.

They’d be amazed by the high tech of today. And they’d love it.

Given the opportunity to inspect a restored 1932 Harley flathead with a state-of-the-art diagnostic tool, the Fluke Ti32 Industrial-Commercial Thermal Imager, we jumped at the chance.

’32 Harley - Fluke Ti32. There’s a nice symmetry.

The motorcycle, restored to showroom condition in 1997, had just completed a 90-mile run across the North Cascades Highway in Washington. It was running strong, but we noticed the powder coat on the rear cylinder near the exhaust port was starting to break down. Was there excessive heat? The Fluke Ti32 would be our guide.

The testing procedure was pretty simple. We rolled the motorcycle out of the garage one morning and shot a thermal portrait with the Fluke imager. There wasn’t much to see in this first image, which wasn’t surprising. The motorcycle, driveway, and surroundings were all at the same temperature after sitting overnight.

IR-Fusion® combined visible light and thermal image of the 1932 Harley Davidson just after it was fired up.

Things changed quickly when we kicked the motorcycle to life. The exhaust pipes heated up instantly, and in a thermal image they stood out in sharp contrast against the cooler cast iron cylinders and heads. We saddled up, shoved the motorcycle into low, and pushed the foot clutch forward.

A five-mile ride through the neighborhood changed everything. With the engine fully warmed up, the Fluke Ti32 made the range of temperatures in the old engine easy to see. We saved these images in the imager’s IS2 format.

Software for the Hardware

The Ti32 can save images in other file formats available (bitmap, for example) but the IS2 format offers the widest range of choices when you engage the other player on the Fluke thermal imaging team: Fluke SmartView® software. Frankly, SmartView was a revelation. It was easy to adjust the color palette and image contrast, and add notations.

Thermal image taken with a Fluke Ti32 showing the rear cylinder running hotter than the front cylinder.

Brighter colors in thermal images usually mean warmer temperatures (as indicated by the temperature scale on the right side of each thermal image), and sure enough, the image showed that the rear cylinder was indeed running hotter than the front. . (Visit the Fluke Thermal Imaging Training Center to learn more about evaluating and solving problems with thermal images.) The real question is whether this is a problem. The rear cylinder may be hotter simply due to the Harley’s V-Twin design in which the rear cylinder doesn’t get as much cooling air as the front. Or it could be something more serious. A manifold leak that allows air into the rear intake could create a lean mixture and result in overheating.

As the scientists say, further research is needed. Anyone know of a manifold leak tester as easy to use as the Fluke Ti32?

Spec vs. spec

Fluke Ti32 Industrial Thermal Imager

Resolution: 320 x 240
Temp range: -40°F to 1,1120°F
User Interface: Intuitive three-button menu; one-hand operation
Viewing Modes: Fluke IR-Fusion® aligns visual and infrared images
Features: Field-replaceable batteries; voice comments for each image
Software: Fluke SmartView® for analysis and reporting
Drop Test: 6.5 foot; resists water and dust
Applications: Inspecting mechanical, electrical and HVAC equipment for temperature anomalies that may indicate need for repair

1932 Harley-Davidson V “Big Twin”

Displacement: 74 cubic inches
Compression: 4:1
Horsepower: 28 hp at 4000 rpm
Transmission: Three-speed, hand shift
Wheelbase: 60 inches
Weight: 529 lbs
Top Speed: 75 mph
Applications: Law enforcement and utility transportation. Forefather of famous 1936 Harley Knucklehead

You can see a four more thermal images of the 1932 Harley Davidson at ’32 on a 32 - 1932 Harley Davidson as seen by a Fluke Ti32 Thermal Imager.

For more information about Fluke thermal imagers, visit the Fluke Thermal Imaging Products page.