Honda-SOHC

I keep wondering WHY did Honda cut down a normal O ring, did they find like Jiutz did that getting the carrier on using a round ring was difficult, it split the ring or forced it out as the hub went on? There has to be a reason, Honda don't do things like this for nothing.

Did they find it fouled and couldn't make the groove deeper as it would compromise it's strength? To me it still makes more sense that they trimmed the top of the ring, just enough to still get a seal but enough that it didn't stop the carrier either moving or being installed without any of the problems they must have found in order to have done this in the first place.

Why didn't they just use a thinner section O ring?

They may have put a flat on the ring so that it not only sat lower but resisted being forced out better as the carrier went on, in which case flat side down also makes sense.

This question is bugging the hell out of me.

Ohhhh and I'm back in the game 

Well.

Checked 2 sets of jets and there is something in there. At first it's not really apparent but when you look through the jet whilst holding it up to an intense white light like an LED you can see what looks like a * in fact that exactly how it looks, 3 lines intersecting in the middle. I checked a set of 069a carbs and a set of 627B carbs and both show this odd little feature. I have no idea how they manufactured them like that. Probing the jet with a piece of wire off a wire brush they all felt the obstruction in exactly the same place, you can actually get the wire down past it by wiggling it a little but the obstruction is right where the body and the narrow tube meet. I measured the wire and it's right there on all of them.

I doubt a wire would break these lines but a drill certainly would. Not wonder my probing with a interdental brush didn't work when I was cleaning these jets. I thought maybe the brushes were too big but it's just that they are too soft to break the mesh.   

Both 500 and 550 use the same pilot jets.

Even when my eyesight was perfect (and I had exceptionally good eyes when younger, still not bad now) I never saw this spider web on the inside of those jets, I've even done what you did and used a piece of wire to clean them out and never noticed any difference in how the engine ran.

That sliding surface looks very dry. How's the corresponding surface on the sprocket carrier?

Is that a piece of garden hose used as petrol pipe? Plus it’s so kinked I doubt petrol could flow down it.

Lot of chrome tarnishing evident, it should sell but not for as much as you expect I think.

Sure somebody on site was after a Hondamans unit recently