9 replies to this topic

[g4321]

I have heard all the stories that modern unleaded fuel goes off and has a very short shelf life - I was a ltlle scheptical but now I know its true.

Took my trusty old TLR to a trial yesterday along with a tin of petrol from the shed - suspect the fuel in the tank was same age - no more than 4 weeks old. Normaly I give the bike a run the day before just to check all is well but this time was a last minute effort.
Loads bike on trailer and off I goes, usually i top up with fuel on the way - dont bother since running late.

Starts bike on choke - sounds bit rough - unusual for this bike, its normally trouble free and was perf4ect the last time I used it. lots of smoke as well - very unusual.
Off choke bike dies - bike wont run without choke at all - frustrated I go through the normal drill, seat off, check air filter aint wet, check carb - jets clear - nothing untoward there.
The petrol did smell flat ie with not strong smell - could it be fuel?
luckily a kind samaritan had 2 litres of fuel so we drained tank, changed fuel and try again - as soon as new fuel got into float chamber the bike cleared and ran like it should do.

Thanks to the two kind samaritans who lent me fuel to complete the trial - Les from Elgin and the chap from the HIA in Inverness -I owe you both a favour.

Then again pity my riding was really poor - even for me - I am blaming the stress of my beloved bike embarassing me by not starting!!!!!!!!!!!!!!

[barrybaines]

g4321, on May 21 2007, 09:34 PM, said:

I have heard all the stories that modern unleaded fuel goes off and has a very short shelf life - I was a ltlle scheptical but now I know its true.

Took my trusty old TLR to a trial yesterday along with a tin of petrol from the shed - suspect the fuel in the tank was same age - no more than 4 weeks old. Normaly I give the bike a run the day before just to check all is well but this time was a last minute effort.
Loads bike on trailer and off I goes, usually i top up with fuel on the way - dont bother since running late.

Starts bike on choke - sounds bit rough - unusual for this bike, its normally trouble free and was perf4ect the last time I used it. lots of smoke as well - very unusual.
Off choke bike dies - bike wont run without choke at all - frustrated I go through the normal drill, seat off, check air filter aint wet, check carb - jets clear - nothing untoward there.
The petrol did smell flat ie with not strong smell - could it be fuel?
luckily a kind samaritan had 2 litres of fuel so we drained tank, changed fuel and try again - as soon as new fuel got into float chamber the bike cleared and ran like it should do.

Thanks to the two kind samaritans who lent me fuel to complete the trial - Les from Elgin and the chap from the HIA in Inverness -I owe you both a favour.

Then again pity my riding was really poor - even for me - I am blaming the stress of my beloved bike embarassing me by not starting!!!!!!!!!!!!!!

Think how long that fuel has been sat in tankers, transport and again at the filling station, I think you're cause is more likely to be down to water contamination than "going off" a little bit of condensation is all it takes!

[GII]

Yes, it does go off, and it smells different too. Though 4 weeks is pushing it, I fill my jerrycan up with 18-19 litres for the 4RT and this lasts 6-7 trials/weeks

Loads of problems with road bikes only taxed for 6 months then SORNED for 6 months,

You can get 'preservative' to put in it, and I've heard that filling the tank / can to the brim then sealing tight can obvert the problem. But, having spent 2 hours trying to start the Honda lawnmower in March (it's always a first pull starter), I drained it off, including the float bowl drain valve, put in a little fresh juice, 1½ pulls and off it went.

I am of course adding the old fuel to the tank once it's running - I can cope with a rough running lawnmower!!

For some reason the 2 strokes in my garage + shed don't seem to have the same problems, there must be a preservative in TTS.

[windlestone]

I've experienced petrol 'going off' a few times too but must admit it's been longer than 4 weeks. Nearest thing i can describe it to is varnish, smell and consistency change. Petrol strimmer is a candidate every year

Edited by windlestone, 22 May 2007 - 07:49 AM.

[g4321]

Quote

Think how long that fuel has been sat in tankers, transport and again at the filling station, I think you're cause is more likely to be down to water contamination than "going off" a little bit of condensation is all it takes!

Condensation was my initial thought and this was what I checked for - definately not the cause. No signs of water in tin, no water in floatbowl and no water in petrol tank. Condensation tends to form as water droplets in the bottom of the tank , the tin or collect in float bowl.

Petrol does have a distinctive smell and this lot smells decidely flat.

The time was 5 weeks - 14th April to 20th may - 14th April was last trial I did on bike and fuel was fresh that day - I think it was the higher octane unleaded I used

There is a chance the fuel in the tin was older but I would have expected the fuel in the bike to be OK after 5 weeks and it was not.

I have left fuel for months before with no real problems - perhaps this time I was unlucky.

[mad4it]

Fuel kept in bulk does not go off very readily but put
it in your tank where it is allowed to breathe and the
octane rating goes out the window about a month is
all you wil get out it being left in the tank before it's
had it.

[muddytires]

I have noticed similar fuel problems with my Tlr200. I rebuilt the motor last summer with probably a little too much compression , so i use higher octane fuel to solve the problem of pinging. But the motor seems very sensitive to the quality of the fuel, two or three weeks after buying fresh stuff it will go back to pinging again. I am about to pull the motor apart again to fix the compression issue with thicker base gaskets and hopefully not worry about this anymore.

[Slawley]

You have to bear in mind that changes in temperature of the fuel can cause it to "go off", especially if its been left in a hot bike then it goes cold that night.

[Brian R]

Muddy Tires,
Send me a PM

Brian

[lastplacebrad]

I read in a trade mag (tool hire) that fuel left in summer hire equipment strimmers, mowers etc needs replacing after been left all winter due to the butanes and pentanes evaporating (i think thats the names!) and these are the parts of the fuel that help ignition.