Its a very cute little engine, but as it hasn't gone wrong I've never had it apart to learn any more about it. But typically, small Honda engines are very well thought out and maintainable.
Talking Honda engines. I've noticed some of the cheaper machines with far eastern made engines have engines that look remarkably like Hondas? Our 18" Rover Mower, like this one:
https://www.sweeneygrassmachinery.com/product/rover-835m103-18/ had a genuine Honda engine - which made it more expensive than the Briggs option at that time. Being the only 18" machine we had, it did a lot of running doing smaller areas and around border edges where the bigger machines were more difficult to manage. It ran pretty much every day and never went wrong in all the time we ran it - probably 10 years or so. It got it's oil changed every 2 months through the season, as did all my daily used machines - straight SAE 30 in them all - It also used noticeably less petrol than the Briggs engined machines, although, to be fair, they were larger more powerful machines. This is the modern version:
https://masportlawnmowers.co.uk/col...r/products/widecut800alsp-selfpropelled-mower which has changed very little compared to the ones I had except that ours had the "trusty" old side valve, cast iron bore, engine. The Hondas which were there when I took over the squad were very good indeed engine wise, never had a problem, but transmissions and chassis parts weren't in the same league. The Masports had aluminium decks whereas the Hondas had pressed steel ones which rusted. The Hondas were good, but the Masports were even better. I think Masport is now owned by Briggs, or maybe vice versa? The biggest single thing I liked about the Masports was the swing blade system which eliminates the possibility of bent crankshafts and makes the blades a lot cheaper to replace. Here's a good video which shows how it works:
We didn't have the chipping blade but we had 2 with the 2 blades and one with the 4 blades - The Rover also had a 4 swing blade system and ally deck, I like ally decks, My own wee 16" cut Harry has an ally deck - Can't say the 4 blades really made any difference I could see - the lawn looked the same no matter which machine was used and all seemed able to cope equally well with longer grass.
By the way, I mentioned earlier that I ran my 4 stroke machines - all the smaller ones anyway, so I don't include the Ferris or Simplicity - on SAE 30. When I started getting involved with small machine maintenance pretty much all these small 4 strokes ran on SAE 30, so Briggs, Tecumseh, Victa, (although Victa were big on 2 strokes) etc, etc. but as the years went by some started specifying multigrades. Of course I initially followed this advice as new machines were bought but I ran into an interesting situation. It's largely associated with machine abuse. I found that some of my machine operators, no matter how much I tried, just didn't seem to have an "ear" for when an engine was straining excessively. This would happen mainly in two situations, either when cutting long grass or failing to empty the grass collector when it was full and just continuing to mow. The result of this use is that the blades can't clear the cuttings into the collector so get clogged with the result that the engine has to work very hard. In the end the engine will stall, but before that it will have been working on full throttle as the governor attempts to maintain engine revs. The result of this is the engine gets very hot indeed and this subjects the oil to extreme stress. Air cooled engines are prone to localized overheating much more than water cooled units and I think the combination of extreme hot spots and overheated - so very thin - oil film causes problems. I had a few problems with the engines running multigrade, bore scoring, rings loosing their tension, etc, but no problems with the ones on straight 30 weight and, knowing a wee bit about engine oils, I think the binding polymers were failing in the multigrade products. I've stopped an operator using a Briggs, running on SAE 30, that had got so hot the engine was smoking - not from the exhaust but from the head and barrel - and after maybe 15 minutes it restarted and carried on as if nothing had happened. I think the straight oil just gets progressively thinner the hotter it gets but the multigrade holds viscosity until it suffers some sort of structural failure when it's performance just "drops off the cliff". So it's SAE 30 for me, until a machine gets really old and worn when some SAE 40 may extend it's working life for a while.
Edit. By the way folks, did you notice how the chap in the video tipped up the machine to look at the blades? that's the way to do it on most machines - I won't be foolish enough to say all machines - Do it this way and the oil is contained in the sump and there's very little risk of fuel leaking out if the tank cap is in good order. I always tip my machines up this way and rarely have a problem unless I'm silly enough to do it with a very full tank. Tip most machines sideways and they'll either leak oil or fuel or both. By the way, you may find it'll need a few more pulls than normal to start after you've put it back on it's wheels because tipping it up may flood the carb.