"Stale" petrol

[awayatc]

Some things one is maybe better of not to know......

[400sm]

Then that's testament to how right Suzuki RM's are in that they can run on the smell of an oily rag.
However your welcome to come round and kick me Norton over with "stale" fuel in the tank anytime...I will enjoy the heap you will eventually be lying in

LOL, I would love to.
I've only been playing with bikes for 40 years, so I'm no expert . . . . but could your fueling come down to contamination in any way ?
When one says Norton, l think, rooly Old.
What is the state of the inside of your bike's tank ?

[400sm]

Fuck my dirt bike is scary on the road and I learnt to ride on an XR with knackered knobblies. I'd claim BS on that claim.

Gas can last well enough but some vehicles better than others. My high compression dirt bike runs like crap when it's cold until it gets totally hot. Then I worked out that if I bought fuel on the way to the ride it didn't happen. Fuel had lost it's light gases through plastic tank. Less detonation in the sand too.

But there's only one person qualified to talk on this subject I'm aware of and he's already spoken. It's not you by the way SM.

That's MEAN Bro :-((

[400sm]

The GSXR (injected) will always start after sitting for months on whatever is in there.

The DR650 how ever seems to cook off the float bowl if not used for 3-4 days. Big single sucks a bit of juice out of battery so not worth cranking it over

Yes the old float bowl scenarios.
Fuel evaporation is indeed a problem.
When left over time, the needle valve can also seize shut, or seize open.
Jets somehow can get blocked too.
This is when the "stale fuel experts" come into their own !
As mentioned, with a bit of a bowl clean, that same old "stale" fuel will start their bikes and take them to the nearest fuel stop. :-))

[Grumph]

Injection has been a godsend to fuel companies. Even when pump fuel is contaminated with water - and has lost most of it's aromatics - the pressure at the injector will still vaporise the muck coming down the lines sufficient to ignite as normal. In my experience this has resulted in fuel with what appears to be shorter shelf life.

Carburettors - especially gravity fed like ours mostly are - are at the whim of whatever shit is in the tank. Extremes of temperature don't help either...

[Macros]

Petrol does decay over time causing the octane rating to decrease.

[breakaway]

Carburetors are shithouse 1950s tech that needs to die.

Virtually no cars come with Carbs now (haven't since the 90s really), yet there are new model year bikes coming out that have this antiquated tech. What's the reason?

[ellipsis]

Carburetors are shithouse 1950s tech that needs to die.

Virtually no cars come with Carbs now (haven't since the 90s really), yet there are new model year bikes coming out that have this antiquated tech. What's the reason?

...probably the same reason that some people walk to work and some prefer a lift...or...

[Mike.Gayner]

Carburetors are shithouse 1950s tech that needs to die.

Virtually no cars come with Carbs now (haven't since the 90s really), yet there are new model year bikes coming out that have this antiquated tech. What's the reason?

Carbs are a simple and reliable device. I don't know why you think they're "shithouse" - they perform extremely reliably for their given task.

[R650R]

Carburetors are shithouse 1950s tech that needs to die.

Virtually no cars come with Carbs now (haven't since the 90s really), yet there are new model year bikes coming out that have this antiquated tech. What's the reason?

Engine-bay real-estate and ease of manufacture, size of injectors makes for more compact engine size.

Nothing wrong with good old gravity fed carb, just spent some dollars on a new Flatslide for the DR650

Injection is great until... at higher mileage the injector tip wears/breaks, high pressure fuel pump fails, engine computer fails...
I love the injection setup on my 750 but for lots of stuff like the DR, carbs are fine. Set up properly the fuel economy is just as good as injection.

[Flip]

Petrol does decay over time causing the octane rating to decrease.

Other way around.

Old petrol has a higher octane number.

[pritch]

Years ago when I was reading Yank magazines there were warnings about trying to store petrol. At some times though the quality of American petrol had been rather low.
No idea what it's like now.

[noobi]

Other way around.

Old petrol has a higher octane number.

I think you're right. Octane rating is weird.

Probably something about the important components of the mixture being more volatile, so they disappear faster, so older petrol has a higher octane, relative to when it was fresh.

[Flip]

http://en.wikipedia.org/wiki/Octane_rating

[F5 Dave]

Carburetors are shithouse 1950s tech that needs to die.

Virtually no cars come with Carbs now (haven't since the 90s really), yet there are new model year bikes coming out that have this antiquated tech. What's the reason?

I think you'll find that has more to do with emissions that everything is changing to FI. Obviously FI has decreased in price every year and multiple injectors and throats provide an increase in performance where bikes have had on throat per pot since the japs got involved. As far as being 50s tech - they are of course 'before turn of the century before that' tech.

But also consider that as recently as the last 125GP racing (ended 2011) the highest output per litre class we've seen yet by quite a bit, well they could have used FI. But they chose carbs. So don't be so quick to diss an engineering solution because of fashion. In some applications DOS is a better platform than W8.(think battery life).