If the flywheel is loose from the crank and you now can't get the bolt undone, remove the rocker cover and see which of the cylinders has closed valve. Remove the Spark Plug from that cylinder and see if the Piston is at least some way down the bore and feed some rope in to the cylinder - be sure to put a decent knot in the loose end so it doesn't fall in ! Then turn the crank until the piston starts to take up on the rope, check that the valves are still closed, if so, keep going until you've undone the bolt. You may have to change cylinders with the rope as you need to catch one on the compression stroke with the valves shut so you don't bend them.
The official Torque figure for the Bolt is 112 - 115 ft/lb. I think I've only ever done it to that figure 2 or 3 times when I first started tinkering with these engines. I've almost always found that figure too low and many engines that had been untouched since leaving the factory, upon going to undo this bolt, I have found them not tight at all and some could even be undone with the fingers. On removing the flywheel on some of these, there's been evidence of fretting between the crank and flywheel. Reading these pages, this it seems to me just about every Verto type clutch set up suffers also from this, only worse.
Where I'm going with this is that my own findings and belief is that Torque figure of 112 - 115 ft/lb is too low and the Locktab here (even the originals) don't help either, they just squash up from torsional vibration causing a slackening in the Tension here. It is poor practice I must admit, I don't use a Torque Wrench on this Bolt and I use Loctite on the threads, but back tracking a bit here, I first lap the flywheels to the crank every time I fit them. Usually after the first time a crank and flywheel are mated, I find just 1 - 2 - 3 turns of the flywheel is well enough. I then clean the mating faces with thinners, I believe they need to be very clean, then lightly lube the taper with 3 in 1 Oil, fit the Flywheel & Lockplate, Loctite on the threads on the Bolt and I then tighten the Bolt as Tight as I can get it, I'd estimate in the order of 200 ft / lb. I've never had an issue, not even come close, with breaking bolts, stripping or pulling threads ever from doing them this tight. The 3 in 1 Oil being so light, firstly allows the tapers to slide and really pull down hard on each other and then under the extreme pressure generated here, the Oil Film breaks down, so I wouldn't ever use anything heavier than 3 in 1. I've found on removing the Flywheels when fitted this way, they are still on tight and never had any sign of fretting. If they fret, as many of us have seen on the forum, they 'weld' together and become very hard to separate, often doing damage to the tapers, some even needing a replacement Crank as a result.
Others here may disagree with this method and what I've said about the Torque Figure on the Bolt and that's fair enough, I'm only passing on my experience here. My experience of finding loose Flywheel Bolts hasn't been just on performance engines but even the standard 998 driven by Grandma.
