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So, having a number of bikes there comes a time when some bikes get used less than others. Probably as long ago as 6 months, I parked up this bike in a perfectly reliable and road-worthy state and now the time has rolled around for me to MOT it again. Although I knew the battery for the original 6V DC system was failing to hold charge for long, I decided to give it the once over and ensure that my battery charger had put enough into it for the active supply when running to power the horn and brake light.

This morning I got up early to check that all was well for me to try and get it in for an MOT, only to find that the bike wouldn't start. Funnily enough, it did fire a couple of times (I kid you not) so I thought it might burst into life after a few more kicks, then a bump... but no Lift the seat and check fuel in tank (fine). Panel off to see that fuel is visible in the clear fuel line (fine). Swap out plugs again, checking for decent spark (fine). After many attempts I decided that stripping the carb might be a good idea... and look what I found!!!













Bearing in mind that the fuel in the tank looks fine, as does the fuel in the fuel line, how the heck can this be the state of the fuel in my float bowl?! I had this happen once before, decades ago, when leaving my bike out the back of my digs and finding that the oil separated from the fuel on cold nights, however, this is something else! When this happened, way back when, I was using good quality Rock Oil, today's example is on the same Groundsman that I've used without issue for a number of years and have never previously had a problem with.

Is this going to be another example of the fuel changing specification?

Your thoughts very welcome.... and take this as a warning to the rest of you that leave a bike standing for any length of time (if that is a contributing factor).

Adam

PS - All parts cleaned out, then doubled cleaned with spray carb cleaner, the fuel flows freely from the tank/tap and the bike runs fine!

PM sent.

Post it on here Capt. as it is too good not to share!

you had some one sexually attracted to your scoot by any chance

Feedback so far:

The oil in the carb has reacted because maybe it's reacted with the oxygen in the water and air drawn in through the carb vents? It's possible with such a small volume of fuel in an oxygen rich environment. Also, the fuel will contain ethanol, which could also be the reason for oxygenation. I would have to do a bit of research in to the fuel contents and the reactions involved.

Written by biochemist.

CONTINUED...

She did explain more but didn't write it down, she mentioned dissimilar metals in the carb, varying temperatures through the day is it in a warm garage subject to changes in temps day and night or and a humid environment the carb interior is subject to free radicals in the fluid all effected by the environment & temps it's kept in.
The fuel tank likely has a larger and much more different or stable environment altering the effects on the fuel.


Funny that she said about the range of metals in the carb as it looks as though the alloy of the float bowl has almost been etched with oxidization where the gel has formed, much like the white crust that you get when alloy casings weather/oxidize, and the brass body of the main jet holder has turned a slight purple colour where the gel has built up on it.

This is a regular science experiment!

Adam

Adam
I think I'd look for something more straightforward than chemical reactions and nuclear fission, mainly because I don't have the mental capacity to deal with things like that.
My first thought was 'water in the fuel', maybe settled in the bottom of the tank and some got into the float bowl.
That could happen if the fuel was contaminated with water at the petrol station, or if somehow it got into the tank via the filler cap.
It happened to me many moons ago when I had an old Vauxhall Cresta with the filler on top of the back wing, and the rain gradually leaked into the tank, settling at the bottom until it built up enough to get into the fuel system. In the fuel pipe and carb water looks very much like petrol, and smells of petrol and I only realised what was going on when my mate dropped his fag in the pool of 'petrol' on the floor and it didn't catch fire !!
Is there definitely no water at the bottom of the tank?
Worth a look and cheap solution if that is the answer.
Nick

nickwill wrote:Adam
I think I'd look for something more straightforward than chemical reactions and nuclear fission, mainly because I don't have the mental capacity to deal with things like that.
My first thought was 'water in the fuel', maybe settled in the bottom of the tank and some got into the float bowl.
That could happen if the fuel was contaminated with water at the petrol station, or if somehow it got into the tank via the filler cap.
It happened to me many moons ago when I had an old Vauxhall Cresta with the filler on top of the back wing, and the rain gradually leaked into the tank, settling at the bottom until it built up enough to get into the fuel system. In the fuel pipe and carb water looks very much like petrol, and smells of petrol and I only realised what was going on when my mate dropped his fag in the pool of 'petrol' on the floor and it didn't catch fire !!
Is there definitely no water at the bottom of the tank?
Worth a look and cheap solution if that is the answer.
Nick

Your 100% right in my estimation it' is caused by water but she was trying to explain why the different reaction in the carb and not the tank...


but it is Certainly some kind of a chemical reaction that's happened, my daughter just explained to me what she thought it was and how she thought it had happened. She did say that without a chemical analysis she could only take a guess but it was her best guess.

Yep, agree with comments above and have repeatedly suffered from water in petrol over the years (different bikes, different petrol stations, different types of petrol, different countries, different times of year), however, I've never had a reaction like this before. Water may well have been one of the factors but this certainly isn't just water contamination, more a case of a chemical reaction in which water may have been one factor or a catalyst. Water is very common in fuel, seems to be becoming more common, but this is not simply a pool of water, or beads of water, getting sucked up into the main jet occasionally, this is very odd.

Thanks for the feedback though, all good food for thought.

Adam

certainly looks like emulsification, certainly when ive laid bikes up ive never had problems in the tank, but ive always made sure to drain the carb and pipe feed too.

Good informative posting.
Frightening !