Restoring a 1960s Diablo Rouge Snowmobile: Will It Run After Years of Neglect?

The Diablo Rouge Snowmobile Project

• 💡 The team acquired a Bolan Diablo Rouge snowmobile, a rare and unusual "chariot type" vehicle from the late 1960s, as a bucket list item.
• 🎯 The goal is to get at least one of these neglected machines running and riding, despite having little prior knowledge of them.
• 🔍 The snowmobiles consist of a separate engine/track unit and a sleigh-like seating unit, with the specific model featuring a 20 horsepower, 300cc Hirth single-cylinder two-stroke engine.

Engine and Mechanical Challenges

• ⚙️ Two primary engines were assessed, with one having a broken engine mount and the other a seized recoil starter.
• 🛠️ The team decided to pull both motors for bench work, discovering significant issues like scoring on pistons and cylinders, and a lack of available gaskets.
• 💡 A single Hirth HR carburetor rebuild kit and one spark plug were acquired, necessitating a focus on building one functional engine from the available parts.
• ⚡ After cleaning points and addressing corrosion, spark was eventually achieved on one of the engines, though it was noted as not being the strongest.

Chassis and Component Swaps

• 🧼 The team decided to use the chassis from one sled (nicknamed "Bikini Bottom") due to its better condition, despite it missing control panel components.
• 🔧 The handlebars and control panel were swapped from a rougher chassis to the preferred one, consolidating the best parts.
• ⚙️ The Tillotson HR carburetor was disassembled and cleaned, with diaphragms expected the following day.
• 🚗 The sled's track system features bogey wheels with rubber bump stops, and the rear sleigh unit has a simple leaf spring for suspension.

Carburetor and Initial Start Attempts

• 🔧 The Tillotson HR carburetor was rebuilt, and initial attempts to start the engine using WD-40 and brake cleaner resulted in pops but no sustained running.
• ⚠️ A significant issue arose when the drill used for starting broke, and the engine seized after initial pops, possibly due to flooding or internal damage.
• 💡 A new spark plug was installed, and after further carburetor work and adjustments, the engine began to run, albeit loudly and without a muffler.
• 🚀 The team aimed to get the engine running consistently, noting that it ran without choke, suggesting good crankshaft seals.

Clutch Issues and Track Repairs

• ⚙️ A major problem was discovered with the clutch system, where bolts holding the secondary clutch plates together prevented it from opening and engaging properly.
• 🔧 By swapping a functional clutch from another machine, the issue was resolved, allowing the belt to engage correctly.
• 🔩 Broken and bent track cleats were repaired using steel bars and carriage bolts to reinforce the track, preventing further damage to the drivers.

Final Testing and Road Trip

• ✅ After repairs and adjustments, the Diablo Rouge snowmobile was able to run and be ridden, though it required significant throttle and had a loud exhaust.
• ❄️ The team loaded the snowmobile for a trip north to Minnesota, hoping to ride it on snow.
• ⚠️ Upon arrival, the snowmobile experienced further issues, including the recoil breaking and the engine seizing again, likely due to heat cycles and piston scoring.
• 💡 Despite the setbacks, the team managed to get the snowmobile running intermittently, completing test laps and a short ride, concluding that while fun, it was a challenging restoration.