Hope you are recovering well, AVB. I love my spices, but have friends that have to be careful so as not to disrupt the natural order in their guts.....

If many motors of this size (ride-on) give up after 600 odd hours, and my failure is rare, what commonly kills them?

Is there anything about mower engines that kills 'em quick? It seems to me that 600 hours is, as I said previously, equivalent to not many kilometres by a car (@60kph= 36,000km). I would have thought that 20hp on a ride-on the size of a Greenfield would hardly be labouring doing what it does....... Does being air cooled make a significant difference? I don't think any motorcycles would expect the same lifespan as a car engine, but they are generally higher performance units.

I would do at least 2 hrs mowing a week, and this would mean that from new I could only expect 5 or 6 years before replacing. To be honest, I would be disappointed with that, particularly had I maintained it as per schedule.

Genuine Hondas are not in a different league altogether?

Norm, I'm glad to see my measurements were at worst only 0.58mm out. It wasn't easy to get a perfect measurement using tape measure and estimated centres, although I did end up measuring side to side, rather than centre to centre. Interesting to see the spacings are not whole numbers (mm) or even common fractions of inches (7.07 inches?).

I better go and push that long suffering Victa pro460 2 stroke around a bit. $30 at the markets years ago. I reckon it has done 600hrs for me and is still going strong (I hope I haven't jinxed it).

Having heard that most ride on motors only run for less than a thousand hours means that the second hand Greenie I'm looking at will want a Chonda very soon as it has over a thousand on the clock. It mightn't be the original though, and as it had a new deck put on it a couple of years back, and drives well, I won't be that disappointed.

Probiotics might help, AVB.