NB: These instructions are given for guidance only and cannot engage the author's liability in the event of misinterpretation, failure to assess the vehicle's actual condition and/or non-conformity, unsuitable mechanical practice or the use of inappropriate tools.
Fitting the primary chains
- Triplex chain: the chain offered (DID) is a reinforced type that exceeds the original chain's specification.
- Simplex chains: as used on 120° engines, of original quality (Regina, IWIS or DID). Fit them carefully, as the original sprockets are often worn and the chains can then run unevenly relative to each other. Replacement is advised between 15,000 and 20,000 km depending on use (sooner with hard use, if they become noisy or if the tension needs frequent adjustment). Never hesitate to replace them if in doubt: the primary drive is heavily loaded on Laverda engines.
- Tensioner blade: caution! Despite an identical part number (31 310 217), some tensioners are 5-10 mm longer than the originals. On triples, this extra length can interfere with the oil-pump gear: as done at the factory in the 1980s, cut a small notch in the blade to avoid any contact.
- Assembly: identical to the original procedure. Check that both sprockets are perfectly aligned and free of deformed or broken teeth. Simplex chains sit on the two outer rows of teeth, one either side of the centre row. Do not hesitate to replace the clutch-drum cush rubbers if old, and the tensioner blade if too marked.
Tension
The dynamic method (engine running, tightening to a whine then backing off) is not recommended. The original system is more a guide to limit chain movement than a true tensioner; excessive tension can seriously damage the crankshaft and gearbox bearings, the blade, the primary cover, the sprockets and the chain itself.
Correct procedure: slowly tighten the tensioner screw until slight resistance is felt, then back off half a turn. Better a slightly slack chain than an over-tight one. Fit new or annealed copper washers, tighten the nut then the cap lock-nut. Recheck the tension 500 km after fitting a new chain.
Causes of a noisy (rattling) primary drive
- Worn chain.
- Old, collapsed clutch-drum cush rubbers.
- Chain too slack or too tight.
- Misaligned, damaged or worn sprockets.
- Loose crankshaft-end sprocket nut, or insufficient washer thickness.
- Worn bronze bush or needle bush of the clutch drum.
- Excessive side play of the clutch drum.