Mine does the same but is a standard L6, and doesn't appear to have any ill-effects.

Sometimes it primes as per the book, sometimes it takes longer, sometimes it doesn't prime at all, but runs fine in between.

All I've ever thought it might be related to is maybe a vacuum leak(?) or a sticky relay. Maybe even a poor earth/supply to the fuel pump, but as it runs normally I'm not sure that'd be the case.

Dean Saff

Mine always fires on the third or fourth turn of the crank regardless of the pump priming the line, does yours have a problem starting?