Does Petrol Really Go Off........

[Shandy]

............seriously does it??

I've had about half a tank of it in the monster over winter and i'm having some problems getting it started. I know its a bit cold out there at the moment which never helps, but at the moment it kind of fires but won't stay running and wondered if it could be fuel as everything else seems ok?

So if fuel does go off, what happens to it, does it just go mouldy like the milk i left in my fridge for 4 weeks??

Cheers,

Shandy

[SJR999r]

yes,it leaves a 'wax' ......doesnt mix well with jet needles or injectors.....makes my 900SS run (when it does start) like a bag of ****e

[retskcid]

Yes, it does. I dont know the technical term, but I believe parts evaporate and leave behind a gooey residue - blocking fuel lines etc. Thats why I run bikes once a month when not in use. I recently sold a Blade that sat for a year with no fresh fuel and it was fine - ran it once a month on average.

On the other hand a neighbour had to strip the carbs on his bike because he left it in storage for months on end without running it - the fuel had gummed up.

I would try emptying your tank and use fresh fuel..good luck.

[SJR999r]

the fireblade ran fine........cos its a HONDA!!!!!!

[Stafford]

It's not the petrol going off Shandy it's the puddle of it under your bike that's the problem!

[JMo]

Some say it does, some say it doesn't... my Monster has been fine the last 6 months in storage (started it twice), but you might find that carb'ed bikes suffer more then EFi?

xxx

[Shandy]

Yeah sounds reasonable that stuff evaporates off, i would like to know the science if someone does know.

I'll drain it off in the week, fill it up with fresh and see waht happens.

It's not the petrol going off Shandy it's the puddle of it under your bike that's the problem!

That was one time last year when it had a wee wee on the road, hopefully it doesn't do it again!!!! :hissy:

[gary tompkins]

I think it looses some of it's ooomf (technical term) as it degrades, as well as leaving a residue in carbs,injectors etc.. as it evaporates. May explain why bikes get harder to start on old fuel - I know mine always run better on fresh petrol rather than stuff that's sat in the tank for ages?

[barbican]

Apparently (and I only read this on some other site so...) over time the fuel particles polymerise in the presence of air, moisture, and metal, this is effect is made worse when petrol from different crude sources are mixed.

Over time petrol molecules change and form tars varnishes and acids which can cause sludge and/or corrosion

The presence of water can promote fungus and bacteria growth also causing corosion and blockages

Having read this I can't sleep at night - but apparently adding XYZ miracle cure solves the problem!

Have noticed the effect far more in some engines than in others, especialy in an old lawnmower (1930 J.A.P engine) with brass tank and carb

[Nickj]

That'll be because the JAP is a child of a different age when the air was purer, the skies bluer and fuel was fuel, you could do lands end to john'o'groats and still have enough left for your next weeks daily commute miles on a teacup full. The kind of people that say this of course are all well into the age of severe senility so it might be a slight exageration.

The grass was softer too says the same impecable source, the modern seed blends do have more tough grasses in them so that is probably true.

Octane content was generally higher I think (5 star equivalence plus) and power outputs a little meagre so you would notice the loss more. There were fewer additives so probably less odd chemical reactions but the quality did vary between brands.

[Gilps]

I've not had a problem with the carbed bikes as long as I turn off the fuel tap and run the engine until the carbs are dry. I leave the fuel in the tank over winter and have no probs. I don't do anything with the injected bikes, just leave the fuel in there and fire up again in Spring, no problem. However, I always use the higher octane stuff and I think this is less liable to going off.

[retskcid]

the fireblade ran fine........cos its a HONDA!!!!!!
Good point :biggrin:

Its only a hunch, but I'm guessing its less of a problem with FI bikes as there is less chance of air getting into the system and to the fuel, hence if you drain carbs when first stored you are less likely to suffer.

[Pedro]

............seriously does it??

I've had about half a tank of it in the monster over winter and i'm having some problems getting it started. I know its a bit cold out there at the moment which never helps, but at the moment it kind of fires but won't stay running and wondered if it could be fuel as everything else seems ok?

So if fuel does go off, what happens to it, does it just go mouldy like the milk i left in my fridge for 4 weeks??

Cheers,

Shandy

Bloody hell, does that mean you're actually gonna ride it soon?

[Shandy]

I've not had a problem with the carbed bikes as long as I turn off the fuel tap and run the engine until the carbs are dry. I leave the fuel in the tank over winter and have no probs. I don't do anything with the injected bikes, just leave the fuel in there and fire up again in Spring, no problem. However, I always use the higher octane stuff and I think this is less liable to going off.

Cheers Gilps now that sounds like good advice which I didn't do any of, ah well :Furious:

I'll drain it all down in the week and squirt some fresh fuel staight down the throat of em, that'll get it running enough to draw some fresh through from the tank!

Bloody hell, does that mean you're actually gonna ride it soon?

Well if it was an old nail like your two it would have been out ages ago.......lol

Hoping to get out soon for a few runs before heading to Le-Mans mid may, i'll give you a bell when i do head out see if your about.

Cheers,

Shandy

[barbican]

I'll drain it all down in the week and squirt some fresh fuel staight down the throat of em, that'll get it running enough to draw some fresh through from the tank!
Shandy

If it is a bit gummed up you'll need a bit of carb cleaner to get the gum to disolve, seems unlikely unless it's been left for months.

[russ77]

If it is a bit gummed up you'll need a bit of carb cleaner to get the gum to disolve, seems unlikely unless it's been left for months.

Bradex is your friend. Conventional wisdom says it is still better to leave the tank full over the winter if you're not riding, to prevent corrosion of the inside of the tank caused by condensation. The condensation could be the cause of the problem too, since water is more dense than petrol, it will have sunk to the bottom of the tank.

[Shandy]

The condensation could be the cause of the problem too, since water is more dense than petrol, it will have sunk to the bottom of the tank.

Top prize for you russ, drained the carb bowls and there was a mixture more water than fuel came out. tried starting again and away she went!!! Ran a bit pants for a while but that soon smoothed out. Going to chuck some pro-fst into the two thirds remaining in the tank for a bit of a wash through on a good run sometime. Just very please it works again!!!!! :mand:

Cheers All,

Shandy

[S4R Dude]

A trick us trail bike riders use, when the bike is left standing for long periods between rides, is only ever to fill with something like Optimax or the expensive option of whatever the garage sells. Ther is always an option for higher octane rated fuel.

This stuff does not go off 'overnight' like the usual stuff.

Cheers. Carl.

[JMo]

A trick us trail bike riders use, when the bike is left standing for long periods between rides...

...is to ride more often?! x

As for petrol 'going off', I can now categorically say it's bunkham... the last time I filled my monster tank was last September (2007), left it in the garage until January this year, when it started on the button. Left it again until two weeks ago (mid May) - started first time again and ran perfectly too...

I'm sure it drops an octane or two, but unless you are racing and/or wanted every last bhp out of your engine, it really doesn't seem to matter...

When it comes to topping up the tank with some fresh stuff, then maybe go for super unleaded like Carl suggests? (that is if you can bare to pay the price - the vintage stuff in my tank cost 87p a litre as I recall... ah the good ol' days...)

I reckon if it's a carb'd bike then it is more likely some goo/residue in your jets causing the problem, rather than 'stale' fuel...

xxx

[S4R Dude]

Ahhh the brown petrol goo...pure evil that stuff!

[YoungDucS4R]

If my experience counts for anything then petrol does not go off!

I had a Yamaha DT250 which I "laid up". This entailed turning off the petrol tap and draining the carb. I also stuck a matchstick up the tank vent (a rubber tube coming out of the filler cap!).

Eleven (yes 11!!) years later ( a long long story) I squirted some oil in the bore, opened the tap and took the matchstick out. Within six kicks on the kick-starter it was firing and running!

It took a while longer to free up the clutch, buy a new battery and renew the tyres, but that tank of petrol kept the engine running till the next fill up.

........or was petrol different in the "olden days" of the 1980's??

[S4R Dude]

I believe petrol then had a higher octane rating?

Which goes with the theory of my using the higher rated petrol in the trail bike as it is often laid up for periods.

I don't rightly know though!!

I can say that it is a right arse to start if i use the cheap stuff.

All stuff to ponder.