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Thread: PEG not starting after sitting more than a week - anyone found the real reason?

  1. #1
    apriliaforum newb PeggyBob's Avatar
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    Cool PEG not starting after sitting more than a week-two, anyone found the real reason?

    Me just opening a discussion about this problem, as may be usefull to every Peg driver out there.

    While reading the forum posts, it was very rare to find/get the real answer on this! So, I am scared to death thinking that this can happen to me as well, specially being far away from home.

    Your experience is really needed in here please,
    so it will be great if the rider who had this issue write the comments bellow!

    Many thanks and safe ride!
    PeggyBob
    Last edited by PeggyBob; 05-15-2019 at 12:24 PM.
    * Aprilia Pegaso 650cc Cube '98
    * MZ RT125cc '00
    * PUCH 250cc '58
    * MZ ETZ 250cc '83
    * Jawa CZ 350cc '79


  2. #2
    apriliaforum Junkie
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    It's not just the Pegaso, but pretty much any bike with carburettors can suffer from this issue these days. The problem is caused by the current fuel formulations. Without some careful analysis it's impossible to know the exact cause, but the most obvious correlation in my experience is the higher than expected ethanol content. I've measured up to 30% ethanol by volume in my local fuels, where the regulated maximum for 95ULG is supposed to be 5%. Ethanol is hydroscopic, which common lore suggests results in carburettor corrosion, but in my experience this is only true if the bike sits unused for very long periods. If one of my carb equipped bikes doesn't start after not being used for a short time, the cause is always always always blocked pilot jets. There's no obvious corrosion products in the jet, although the brass doesn't look as bright as you'd expect; what I always find is some gummy residue, presumably some product of the fuel evaporation, sitting in the bore of the jet.

    Fixing it is easy (just strip the carbs, pull the jets and clean them), but it's a massive pain in the arse. Better is to try to avoid the problem. Draining the carbs sort of works. Running them dry is more reliable (providing you know you're not going to use your bike for more than a week or two, and you remember). Best is to use fuel which you KNOW has no ethanol. For me, in France, a 98ULG bought from anywhere other than a supermarket seems to do the trick.

    A lot of people in forums swear by fuel stabilisers, some magic potions which you add to the fuel to prevent the problem. In my opinion, fuel is expensive enough without voluntarily adding some liquid gold. Similarly, you'll read of many tricks to unblock your jets using other fuel additives or carb-cleaners. They may well work, but I've yet to understand how they manage to win access to the blocked jet when it's above the normal fuel level at the end of a tube... perhaps that's the magic at work?

    If you use a carb-cleaner solvent in an aerosol-can and you can squirt it down the appropriate hole, that'll surely work. How do you get access to this without first pulling the carbs off the bike though?? In which case, you'll be better off just taking out the jet and poking out the blockage and saving your money to buy more fuel!

    Why the fuel companies add ethanol is well beyond the scope of this forum. I'm very sure they know what it does, and I'm also very sure they don't care. Take one look at their annual profits then answer the question: why would they?


    Anyway, rants aside, that's my experience of the subject. Buy good quality fuel, avoid anything which suggests it contains higher than 5% ethanol, and if the problem does happen to you, learn how to quickly pull your carbs and clean your pilot jets.

    Cheers... Paul

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