Tamiyacowboy
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Hello TC,
I hope you don't mind me bothering you like this.
I couldn't help noticing as I trawled through some posts from a few months ago that you have an astonishing knowledge of scooter carburettors.
So I'm wondering if you might be able to offer some insight on a small problem I have with my scooter?
It's a Piaggo Sfera 125 RST from about 1996. It has the pre-leader engine with a Mikuni BS24 carburettor. Now, it doesn't enjoy starting from cold unless I twist the throttle a bit, then release it before pressing the starter. It fires straight away if I do this. This is fine by me, but after a little bit of a ride, or even a long one, if it's left switched off for a few minutes for something like going into a shop it takes quite a few turns on the starter to get going, and then it stutters and judders and won't produce full power for a couple of hundred metres in a very embarrassing and slightly irritating manner, which is exaggerated when you have a queue of impatient cars 2 inches from the tiny rear wheel!
It has defied my efforts so far- the spark plug is new, the air filter clean, the valves set correctly, the fuel tank cleaned out, the carb cleaned, a new tap and fuel lines fitted, the breather tube is clear and I'm all out of ideas!
It will 65 mph on a flat road if I duck down behind the screen and do everything else quickly enough, it's just this juddering thing now
Thank you
Nikki
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hi nikki sorry i not been about much
first off, check your carb connection to the motors manifold, a slight air leak caused by perrished rubber hose/poor fitted clamp - no gasket can provide just enough extra air to cause starting problems . can be either end the airbox hose to carb join or the carb to motor manifold , usually these two places get overlooked.
if that does not help, try tweeking the idle screw slightly to bring up the resting idle, what this is doing is moving the throttle slide up slightly , when your cold start its like an added little extra air and fuel and can sometimes stop poor starting right from the bat. the other area is the coldstarter aka the auto choke, these can start to fail over time and leave the choke semi engaged so it acts up , or just does not open the choke when starting due to it failing.
If all else fails you could come and join The Scooter Shack forum, we have a whole forum of scooter tuners and motorcycle mechanics logging in that could offer other insights that could be the problemheres a link to the shack if you wanna pop by and lurk /read up https://www.scootershack.co.uk/
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Hi TC and thanks. I meant to send that as a PM but somehow clicked the wrong thing
I actually made some progress and discovered that the clircular clip on the needle was on the wrong notch. Also the mixture was causing the spark plug to blacken terribly in no time at all. So I've been slowly adjusting things as and when I have time for a test ride and a check afterwards. It has improved considerably already but I will check the connections you mentioned as well
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awesome news to hear Nikki .
a wrongly re-set needle clip can cause overfueling , if all the above was to fail my last place would ahve been a re-look at the carb and its slide needle settings just to be fully sure .
great to hear the sfera is back to being itself again, i just got new rubber on the piaggio skipper, went with avon viper strykers this time round .Ride safe <3
Tami
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