ORIENTAL ANGLES
Many of us fettling old bikes do it alone in splendid isolation and are happy to do so. The shed/garage/workshop is our ‘happy place’ where we are comfortable doing what we like best. Occasionally, though, there are tasks that need to be farmed out and these are generally the ones that are variously beyond our skill set and/or the workshop resources. None of us have the kit to chrome plate at home, a large number don’t like building wheels, many cannot spray paint to a professional level, etc.
When it comes to obstinate fittings, most of us will have a go with varying degrees of success, generally having the good grace and common sense to know when to walk away. Once you have broken one 6mm thread extractor in an alloy case you tend to understand how not to repeat this frustratingly annoying process ever again. Of course, sometimes bravado, ego or hubris trump common sense and we soldier on, compounding mechanical disasters and thereby turning them into catastrophes when we should have done the sensible thing.
Yamaha dynamos are something of a nemesis for anyone into the vertically spilt stroker twins – they are prone to melding themselves to the crank nose taper. Three legged pullers will automatically destroy the precious windings; the factory puller tool can baulk at liberating its host and even normal all-conquering slide hammers can sometimes fail to dislodge the large mass of metal. Those who know these engines will tell you there’s generally a 15-20% failure rate evicting these devices from their parent taper. Those that don’t will tell you to use penetrating oil, acetone and ATF, apply heat, put the engine in a freezer or even soak the motor in diesel. The reality is that when the rotor of an RD200, YDS3 or Big Bear won’t come off, it simply… WON’T COME OFF!
The only recourse is to cut the old one off carefully, hopefully preserving the crank’s nose and finding a viable replacement. It’s not a fun job and this column once lost seven hours to this very task. But the crank nose was saved, a spare was found and the bike’s rebirth carried on.
On more conventional engines the rotor/ flywheel/magneto is ‘readily removed’ (don’t you love those throwaway phrases?) with a threaded puller. Retaining nut off, puller screwed in, a few hammer taps and you’re good to go. Or not if you own certain Suzuki TS trail bikes... In these cases you have
6mm holes on a 50mm PCD that require a specific type of puller. You can use the ‘hacks’ as shown on YouTube and you might just get lucky. Alternatively, you might very well take out three perfectly good coils that sit under the magneto. The correct tool will normally make light work of the task, breaking the bond between the two tapers with a whip-like crack which oddly scares and reassures at the same time. This noise confirms the job is a good ’un and you can proceed with the rebuild.
When it all turns unpleasant is when you repeat the chore on an identical engine and two things happen – nothing and bugger all. That you know the technique is a given, but why it’s not working on this occasion is frustrating. More leverage on the screw, additional strikes with the hammer, half a can of easing fluid, heat and more heat applied and yet the little git still won’t budge. You now have two options: A – persist with your now floundering modus operandi and know, deep down, it’s likely to fail, or B – call in a professional. The latter may feel like you’re accepting defeat and you know it will cost you, but how much is a replacement? Yes, precisely! Discretion is the better part of valour after all. As Dirty Harry once said in a film: “A good man always knows his limitations.”