Valve recession?

[Subike]

Carbon buildup in the combustion chamber and on the back of the valve, is two things, poor quality fuel and oil from the engine.If you want to see less/no carbon buildup , use caltex fuel.

Is this because Caltex use stricter quality controls on their production process and delivery?
Or because the additives they use are more engine favorable than environment/ sales promotion propaganda favorable.
I believe that Caltex oil products are better quality than most that are available on the market.

[bsasuper]

I always filled my work car up with caltex, 4 years later I had a look down the inlet, valves were clean ,I mean zero carbon buildup.A bike I purchased used had carbon buildup on the valves, so I used only caltex fuel, I checked 3 months later and carbon was gone,the techron additive they blat on about actually works.

[jonbuoy]

Maybe some of the carbon build up is down to how the engine is run, a good run up to the blood every now and again helps clean the system out.

[SS90]

This is the type of wear I'm referring to.

As a sideline to my day job, I restore ultra light weight Italian 4 strokes (50 to 100cc 4 strokes from the early 60's mostly) things like Moto Morini Corsarinos as an example.

Quite often I come across rooted inlet valves, it would seem that valves where a problem on such small "performance" bikes.

Generally, inlet valves (actually all 5 I am currenly doing) look exactly like the computer image

A while back I mentioned to a highly experienced machinist (no google searches in his day) as to why they all looked like that (bearing in mind these bikes generally have not run since the 70's at best, so unleaded fuel is not the culprit)

His opinion is that simply rich running was/is the cause, and this ties in with the fact the the old carbs on these sort of bikes where shit when they where new, and they are no better now.

Rich running may or may nit be your cause, but it certainly is for the old Italian ultra light weights I see, and the valve damage seems neigh on identical.

[Crasherfromwayback]

His opinion is that simply rich running was/is the cause, and this ties in with the fact the the old carbs on these sort of bikes where shit when they where new, and they are no better now.

Rich running may or may nit be your cause, but it certainly is for the old Italian ultra light weights I see, and the valve damage seems neigh on identical.

What's his reasoning for it?

[scumdog]

Maybe it is? How many car motors ever have the head off before they finally make it to Pick-a-Part? When I was working as a mechanic (Mitsi/Chrysler dealership) a valve grind was par for the course at around 50,000 miles, especially on Hunters and Avengers.

Way back then I got the impression that a fair number of those valve grinds at 50,000 miles were done simply because 'That is What You Do' at that mileage rather than obvious evidence of a need for it.

And I use to worry about that sort of thing back then too.

Now I just drive/ride 'em until 'something' happens.

And so far the only obvious sign of valve-seat recession on zany of our vehicles was on Mrs Scumdogs little Anglia when the valve-clatter disappeared - and so did the compression and smooth idle.

SO...I re-set valve clearances and all was sweet for another year or so.

[ducatilover]

I wonder how the direct injection petrol engines will last?Camhaft lobe wear is more of a problem these days.(who measures lobe wear when doing a shim check).

Why wonder now? Look at the valves on any GDi Mitsi, shocking heaps of shit those.
And yes, I measure my lobes