dirty valves

I just removed the carbs from my '01 SV650S for the first time and was surprised at how much carbon build up is on the backs of the inlet valve heads. The ports are clean and so are the valve stems, just the valve heads are carboned up.
The bike runs great and doesn't burn oil, but there is more crap on the valves than I'm used to seeing on my old BSA's.
Anybody else noticed this?
Oldie

The thing is, you had the valves out on a BSA every week to regrind them, your SV has lasted 8 years to get to this state.

There speaks a man with experience!

Originally Posted by Jester666

There speaks a man with experience!

The only British bike I have ever owned was a 2004 Triumph Daytona 955i SE. When I was a lad I remember seeing all the local bikers working on their old BSAs, Velocettes, Nortons and Triumphs. Every weekend they'd have the useless piles of crap in bits, and every time they saw a Jap bike go past they'd sneer and call it Jap Crap. I often wondered how the jap bikes could be crap when they kept running and promised myself I wouldn't own a British bike until they finally made something I liked the look of that was reliable and affordable.

I started riding in 1978, the day I bought a British bike didn't happen until late 2006.

[embee]

The build-up on inlet valves depends on a lot of factors, not least the fuel quality, the oil used, the blowby rate, oil carry-over in the blowby, how hot the inlet valves run etc.

It can be useful to use some carb/injector cleaner on occasion if your engine is prone to these deposits, it can help minimise the build-up though it won't usually clean it off if it's been baked on.

As an aside, I personally wouldn't have a direct injection gasoline (petrol) engine car yet, the ones I've had development experience of all suffer drastic deposit build-up on the backs of the inlet valves (due to not being washed as with port injectors). I've recently been doing air flow measurements on a certain German manufacturer's engine, it had done 9k km in a car and the deposits were so bad the airflow was down by best part of 5% compared to when they were cleaned. Another German manufacturers DI engines are just as bad.

what fuel / oil are you using ?

cheap supermarket fuel, and /or basic mineral oils can also contribute.

I've been doing some work with Jaguar on their new direct petrol injection 5L V8 for the new Jag - it needs a very special 5W-20 oil designed to help keep the valves clean ( and work the variable valve timing ). I used a pic of a valve from a mates GDi Volvo for the presentation to show them what can happen - the carbon was that bad it had completely blocked the head so the cone of carbon built up on the valve was the exact fit to the conical hole in the head that it fitted into !

Mitsubishi GDi engines are notorious for it - they have a specific oil designed to help the problems - but using an oil that is less volatile and prone to oxidation such as a full or at least part synthetic will help.

And regarding fuel - I know BP have an Audi A6 V8 that has been modified to run separate fuel tanks in each bank of 4 cylinders - I have seen pictures of the valves ( they have boroscopes down the inlets ) and the ones using BP ultimate are clean as new, whereas ones using supermarket fuels show considerable carbon build up.
Spokey

I tend to agree with Lozzo about the reliability of the old Brit bikes, but between repairs they are great to ride! When I was younger I really thrashed 'em and they broke regularly but now I treat them better, they actually stay together pretty well. I just did the first top end overhaul for 24 years on my BSA Victor and the inlet valve was cleaner than the ones in my Suzuki.
I use Esso premium unleaded in the BSA and Esso regular unleaded in the Suzuki, but I may start using the premium in the Suzuki too after seeing the valves.
Oldie

[johnnyrod]

Embee, would that be a VW Polo by any chance? Or am I too old skool with that one?

Originally Posted by johnnyrod

Embee, would that be a VW Polo by any chance? Or am I too old skool with that one?

Ooh! Scunny!
almost neighbors!
I see you cant say ScVnthorpe on her either... the ISP Demon had a problem with that, nobody could have an Email address with ScVnthorpe in it!

Steve

[embee]

Originally Posted by johnnyrod

embee, would that be a vw polo by any chance? Or am i too old skool with that one?

-owomobo-