Has anyone got any up to date observations about the shelf life and reduced volatility of petrol? Had a lot of trouble trying to get the M20 running this afternoon. I suspect the petrol has something to do with it (bike hasn't been running for a few months). And it also has a wet sumping issue that I've got to sort out. Meanwhile, there's the question of old petrol in the tank.

I know this question comes up from time to time. I'm just trying to get the latest feedback. Any comments, anyone?

email (option): dannydefazio@sumpmagazine.com

I've not had any problems in this regard. I've had petrol in bikes for weeks, even months and they have started without difficulty. Ron Pier for one, I know will concur, as we have discussed this subject in the recent past. When I started the WB30 for the first time I used some petrol from a can which was at least 2 months old and it was fine.
I know with my own M20 that if it is left long enough to wet sump (that takes a couple of months with mine)it is a sod to start and I would think that is at least part of the problem.
Petrol wise? ...no problems for me yet....Ian

email (option): julie@wright52.plus.com

Danny
I think we have talked about this Previously and it was brought to mind recently as I went to Start my FJ1100 which has stood Idle for 12 months and despite having half a tank of petrol a Fully Charged Battery and the Carburetor bowls full it would not even kick Until I Drained the Tank, Carburetor ‘s and refilled them with new Fuel it then started first Kick (electric Leg) this the First Problem I have had with a vehicle although we have had interminable problems with a lawn Mower when Fuel is left in the Tank but this has improved by the use of an Additive We though may have different Fuel mix I.E. more or less Ethenol

email (option): grumpy.moran@gmail.com

Thanks Ian and Ron. The reason I suspected the fuel was because I also had a lot of trouble starting my BMW R80ST. Haven't used it in a month or so. I had to crank it for 3-4 minutes with a support battery before it fired. However, I have had some intermittent problems with this bike regarding the floats (unresolved, but have new ones ready to fit). Usually when the M20 wet sumps (which take a month or so to lose any appreciable amount of oil) it is hard to start, but it generally gives it up after a few minutes. Today that didn't happen (but it is pretty cold and icy down there in the garage).

I checked the internet and opinion (as ever) varies regarding fuel shelf life. As I said, this issue has come up before. I'm just looking for up to date anecdotal evidence, especially as (I've read) the petrol "brew" changes seasonally. Apparently, it's less volatile in the summer, and more so in the winter. The petrol in the M20 is a good few months old. Maybe 3-4 months even.

Also, there might be differences between low compression engines and high compression engines where the compression aids ignition.

Any other views out there?

email (option): dannydefazio@sumpmagazine.com

Its probably the oil in the crankcase causing drag on the crankshaft that made it difficult to start. Both my Commando and WM20 are hard to start when they have wet sumped. And when its this cold the oil will be thicker than usual. Its probably best to drain that oil out, as I said in an earlier post I think crankcase pressure can push it into the primery chaincase where it will contaminate the clutch
I put some 6 month old petrol out of my dirt bike into my Paneuropean, and that ran fine with it. I think the biggest problem with old petrol is it gumming up the carb- not losing its volitity.
Best start them up and get the engine hot every few weeks. Even if you dont ride it out, its good to hear it the run and know that it lives.

email (option): Gasboy@btinternet.com

Good point about the carb getting 'gummed up'...I usually switch off the petrol and let the bike run until it empties the carb if I know I won't be using it...and I use more modern taps which don't leak. Oil viscosity is relevant as well..I used to run my Ariel Square Four on SAE 50 and as soon as the cold weather arrived each year I could feel the difference when kicking it over. I used to run that one on SAE30 in very cold weather...and it has been bloody cold of late!!..Ian

email (option): julie@wright52.plus.com

Having spent 20 years or so in the buisness of repairing and servicing small petrol engines (chainsaws,generators,mowers etc.)i can say that fuel certainly "goes off" if the machine is stored up for any length of time.The problem seems worse if the fuel is in small quantities and if in an open enviroment.I found the best way to demonstrate this to customers was to tip a bit of suspect fuel on the floor outside the workshop at put a match to it,if really stale the fuel would not even light but more usually after lighting would leave an oily residue behind,where as fresh fuel would light well and leave nothing behind.I'm not a scientist and i dont know the reason for this but i suspect it is conected with fuel evaporation.I know there are additives on the market which are supposed to aid storage of fuel and was told by some one some years ago that additives were used when storing fuel in jerry cans during ww2.Any way hope this is helpfull,Merry christmas to you all,Mick.

email (option): sally_jones@btinternet.com

"Sta-Bil" stabilizer saves the day. In the summertime I sometimes don't use the car for months on end. In winter I don't use the bike for months on end. Stabilizer works on both. When I was ambitious enough to mow the grass myself, I also used it in the lawn mower, which obviously was not used for a number of months every year. (My wife was not satisfied with the frequency with which my ambition manifested itself, so some years ago she gave away my mower and got one of the local services to do the lawn - my bad, ha, ha.)

BTW, when running the motor with a closed tap until it's "starved" you don't get anywhere near an empty float bowl. The fuel level drops by less than 25% when the motor stops for lack of fuel. If it's your intention to empty the carb you need to actually empty it by, e.g., loosening the banjo bolt (and collecting the run-off in an appropriate container, keeping in mind how flammable it is). On the other hand, if your present method provides good results "if it ain't broke, don't fix it".

email (option): jonny.rudge@verizon.net