Author Topic: fuel system question  (Read 559 times)


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fuel system question
« on: September 21, 2016, 08:51:08 PM »
'09 Fiddle II 125.  700 miles on it give or take.  I picked it up from the original owner who used it a year or two and then it sat.  Carb was nasty obviously as was the fuel tank and lines.  I removed all parts and ultrasonically cleaned them.  Reassembled and it ran beautifully, I rode it around town a few times and didn't have a minutes' problem with it.

The last few days, however, I've noticed that the engine is a little hard to start when cold.  Actually, impossible, UNLESS the throttle is wide open.  Then after cranking a few seconds, it fires off and it acts flooded.  The autochoke is obviously "on".  After running a few seconds keeping it running with the throttle, it will smooth out, and will run smoothly at a higher idle speed (autochoke) with no throttle input-like it's supposed to.  From that point on, it will run perfect, other than being about 5 mph slower than I expected (tops out at about 51 mph...I hear this is common until it's broken in).  Park it, come back 24 hours later, same thing.  Flooded until it's cleared out.

I'm familiar with carburetors, but I've never run into this before, with it being flooded after sitting all day.  I have noticed no gasoline smell anywhere, no gas stains on the concrete floor where it sits all day, nothing.  It's almost as if the fuel level in the bowl is rising but not so high that it's puking out of the overflow.   Any idea what I should be looking for here? 

I am going to sell it but I don't want to sell anyone something that could be problematic!


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Re: fuel system question
« Reply #1 on: January 01, 2017, 11:37:48 PM »
I've heard this happen before to other scooters. With your situation, it could be one of many different issues.

1. It could be bad gas if you didn't drain the gas tank and put fresh gas in there. Also, crud from bad gas could re-clog the carburetor, the fuel filter, or the petcock (vacuum operated fuel pump). I would still stick with the fluid related issues first if the gas was not changed.

2. Other things can happen, such as cracked rubber in the carb, or vacuum lines.

3. A readjustment of the air/fuel mixture could be needed.

4. You might need a new spark plug if it happened to get fouled from bad gas or poor idle mixture.
2009 SYM FIddle II 125 (~155cc)
NCY 58.5mm big bore kit, NCY 58.5mm large valve head, NCY CDI, A13 camshaft, de-restrict airbox, Malossi kevlar belt, sliders, upjet, wired front factory running lights Big Bore  Airbox Mod  Kevlar Belt