20/10/2012
The classic widecase Ducati engines hold a special place in the hearts of motorcycle enthusiasts, revered for their distinctive character and performance. When it comes to intricate engine work, understanding the nuances of each component is paramount. One such component, often a source of specific inquiry, is the kickstarter shaft. Unlike many other engine designs, the kickstarter shaft on widecase Ducati engines exhibits a unique characteristic that’s crucial for any mechanic or restorer to grasp: it remains firmly in the crankcases even when the engine halves are split.
This design feature simplifies certain aspects of disassembly while introducing specific considerations for inspection and reassembly. Indeed, you might even find that the return spring can be left in place during the initial separation of the crankcases, a testament to the integrated nature of this particular mechanism within the engine's architecture. For those embarking on a rebuild or deep maintenance, this inherent design dictates a precise sequence of assembly and rigorous attention to detail, particularly regarding its fitment and associated components.
The Integrated Design of the Widecase Kickstarter
The engineering philosophy behind the widecase Ducati's kickstarter shaft is one of integration and robustness. Rather than being a component that can be easily withdrawn once the outer covers are removed, its pivot points and support structures are built directly into the crankcase halves. This means that when you separate the left and right crankcase sections, the kickstarter shaft will stay with one of them, typically the left half (clutch side), firmly seated in its primary bearing surface.
This design choice has several implications. Firstly, it means there's less chance of misplacing the shaft during a major engine strip-down. Secondly, it highlights the importance of the crankcase mating surfaces and their internal bores for the proper alignment and function of the kickstarter. It’s not just an external lever; it’s an internal, load-bearing component that relies on the structural integrity of the engine cases themselves for its operation. This integrated approach contributes to the overall rigidity of the kickstarter mechanism, reducing flex and potential points of failure under the significant forces exerted during engine starting.
Splitting the Crankcases: What to Observe
When the time comes to split the crankcases on your widecase Ducati, a methodical approach is vital. After removing all peripheral components, fasteners, and carefully separating the case halves, you will observe that the kickstarter shaft, as mentioned, remains in situ. This is normal and expected. The return spring, which provides the essential tension for the kickstarter lever to return to its resting position after a kick, can often be left attached to the shaft during this process. This can save a small amount of time and effort during disassembly, though careful inspection of the spring's condition is still necessary once the cases are apart.
The act of splitting the cases provides an excellent opportunity to inspect the shaft and its immediate environment. Pay close attention to the bearing surfaces within the cases themselves where the shaft pivots. Look for any signs of scoring, excessive wear, or pitting that might indicate a lack of lubrication or contamination. The integrity of these surfaces is critical for the smooth, low-friction operation of the kickstarter, directly impacting the effort required to start the engine and the longevity of the component.
Critical Inspection Points: End Float and Shims
The kickstarter shaft is the first item fitted to the cases when assembling the motor, a clear indication of its foundational role in the internal mechanics. This precise positioning is achieved and maintained through the use of shims and a specific tolerance for end float. End float refers to the amount of axial (sideways) movement the shaft has within its bore. For the widecase Ducati kickstarter shaft, there should be very little end float.
Excessive end float can lead to several problems: misalignment of the kickstarter gear with its mating gear on the crankshaft or layshaft, increased wear on the shaft itself and its bearing surfaces, and potentially a 'sloppy' feel to the kickstarter lever. Conversely, too little end float, or none at all, can cause binding, excessive friction, and premature wear due to constant pressure. The correct specification for end float is typically found in your specific model's factory workshop manual, and adhering to this tolerance is paramount for correct function and longevity.
When the cases are apart, it is imperative to check that all the shims are intact and present. These thin, precisely manufactured washers are placed on the shaft to control its end float and ensure correct alignment. They are typically made of hardened steel and can be found on either side of the kickstarter gear or at the ends of the shaft where it interfaces with the crankcase bearings. Inspect each shim for:
- Wear: Look for thinning, dishing, or signs of abrasive wear.
- Damage: Check for cracks, chips, or deformation.
- Correctness: Ensure they are the correct thickness and diameter for their intended location. Often, shims are specific to their position.
Missing or damaged shims are a common cause of kickstarter issues. If shims are worn, they must be replaced with new ones of the correct thickness. If they are missing, consult your manual to determine the correct shim configuration and thickness required to achieve the specified end float.
Kickstarter Shaft Inspection Checklist
| Component | Check For | Expected Condition | Action If Failed |
|---|---|---|---|
| Kickstarter Shaft | Bends, scoring, pitting, spline wear | Straight, smooth, no significant wear on splines | Replace shaft |
| Shaft Bearing Surfaces (in cases) | Scoring, excessive wear, pitting | Smooth, even wear, no deep marks | Machine cases, use oversized bushing (if applicable), or case replacement |
| Shims | Wear, cracks, deformation, correct presence | Intact, flat, correct thickness, all present | Replace worn/damaged, add missing to achieve end float |
| Return Spring | Fatigue, breakage, deformation | Good tension, unbroken, correct shape | Replace spring |
| Kickstarter Gear (on shaft) | Tooth wear, chips, looseness | Sharp, unbroken teeth, securely fastened | Replace gear |
Reassembly: The First Step and Precision
As the kickstarter shaft is the first item fitted to the cases during assembly, its proper installation sets the stage for the rest of the engine build. This means that before mating the crankcase halves, the kickstarter shaft and its associated shims must be correctly positioned and lubricated. Use a high-quality assembly lube or engine oil on all bearing surfaces and the shaft itself to ensure initial lubrication upon start-up.
The sequence is critical: install the kickstarter shaft into its bore in the left crankcase half, ensuring all shims are correctly placed to achieve the desired end float. This often involves a process of trial and error, fitting different shim thicknesses until the ideal specification is met. Once the shaft is properly seated and the end float verified (which can be done with feeler gauges or a dial indicator once the cases are together, or by careful measurement during pre-assembly), you can proceed with installing the crankshaft, gearbox, and other internal components before carefully mating the crankcase halves.
Failing to address the kickstarter shaft's end float and shim integrity at this stage will necessitate a complete engine strip-down later if issues arise. This highlights the importance of precision and patience during the assembly process of these classic engines.
Even with careful assembly, issues can arise. Understanding the symptoms can help diagnose problems related to the kickstarter shaft:
- Kickstarter binding or stiff operation: Often indicates insufficient end float, bent shaft, or damaged bearing surfaces.
- Excessive play or 'wobble' in the kickstarter lever: A strong sign of too much end float, worn shims, or worn shaft/bushings.
- Kickstarter not returning fully: Could be a weak or broken return spring, binding due to incorrect assembly, or friction from lack of lubrication.
- Kickstarter slipping or not engaging: May indicate worn teeth on the kickstarter gear or its mating gear, or issues with the kickstarter engagement mechanism itself, which is often influenced by shaft alignment.
- Noise from the kickstarter mechanism: Could be loose components, excessive end float allowing parts to knock, or worn gears.
Addressing these issues promptly is crucial, as continued use with a faulty kickstarter can lead to further damage to internal engine components, including gears and crankcase bearing surfaces.
Frequently Asked Questions (FAQs)
Q: Can I remove the kickstarter shaft without splitting the engine cases on a widecase Ducati?
A: No. Due to its integrated design, the kickstarter shaft remains in one of the crankcase halves when they are split. It cannot be removed or fully serviced without separating the engine cases.
Q: What is 'end float' and why is it important for the kickstarter shaft?
A: End float is the amount of axial (sideways) movement a shaft has within its bore. For the kickstarter shaft, it's crucial for ensuring proper alignment of gears, preventing binding, and minimising wear on the shaft and its bearing surfaces. Too much or too little end float can cause operational issues and premature component failure.
Q: How do I measure the correct end float for the kickstarter shaft?
A: The precise method and specification will be detailed in your specific widecase Ducati model's factory workshop manual. Generally, it involves using a feeler gauge or a dial indicator to measure the axial play. You adjust this by adding or removing shims of varying thicknesses.
Q: Where do the shims for the kickstarter shaft typically go?
A: Shims are usually placed on the kickstarter shaft on either side of the kickstarter gear, or at the ends of the shaft where it runs in the crankcase bores, to control its axial position and end float. Always consult your specific engine manual for exact placement.
Q: What are the consequences of not checking the shims or end float?
A: Ignoring shims or incorrect end float can lead to a range of problems, including excessive wear on the kickstarter shaft, its gears, and the crankcase bearing surfaces. This can result in a stiff or binding kickstarter, a sloppy feel, or even complete failure of the kickstarter mechanism, requiring another full engine strip-down to rectify.
Conclusion
The kickstarter shaft on a widecase Ducati engine, while a seemingly simple component, is a prime example of the precision engineering required for these classic machines. Its unique characteristic of remaining in the crankcases when split, coupled with its critical reliance on correct shims and minimal end float, underscores the importance of a meticulous approach during engine disassembly and reassembly. Understanding these intricacies ensures not only the smooth operation of the kickstarter but also contributes to the overall longevity and reliability of your cherished widecase Ducati. Paying close attention to detail during inspection and assembly, particularly regarding lubrication and precise component placement, will yield a kickstarter that functions flawlessly for many more miles of enjoyable riding.
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