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Post by RWS74 on Nov 29, 2016 7:49:12 GMT
Wocha folks I got to ride a mate's Vespa PX 125 with a Malossi 166 kit fitted.
20/20 Carb
113 MJ
55/160 IJ
Air filter Drilled.
It did seem smooth & plenary of torque from closed to open throttle with no hesitation at all anywhere in the throttle range while accelerating or maintaining constant throttle however on deceleration from around 55-60kmh the engine sounded a little rough, difficult to describe. With the set up mentioned above what could cause or improve this please?
Ta Muchly.
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Post by pxguru on Nov 29, 2016 9:24:35 GMT
Is this when the throttle is fully closed and rpm is slowing down from speed?
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Post by RWS74 on Nov 29, 2016 9:47:26 GMT
Is this when the throttle is fully closed and rpm is slowing down from speed? Hello mate, from memory as it was a short 10 min ride it probably was. We were riding in 30 & 40mph and rolling off from 30-40 sometimes to stop or just slow for hazards etc. smooth as silk when accelerating though. |
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Post by pxguru on Nov 29, 2016 11:23:33 GMT
Rolling off with the throttle still partially open or rolling off to throttle shut will involve different jets. Which atomiser and AC are fitted? these will matter if the throttle is not fully shut.
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Post by RWS74 on Nov 29, 2016 11:50:34 GMT
BE4 & 140
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Post by pxguru on Nov 29, 2016 12:09:09 GMT
How many turns out is the mixture screw?
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Post by RWS74 on Nov 29, 2016 12:18:06 GMT
How many turns out is the mixture screw? I think he said 2. |
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Post by pxguru on Nov 29, 2016 12:40:30 GMT
It might not be enough. When closing the throttle fully with the engine still at higher rpm the only jet officially working is the pilot jet (only the small number part) through the mixture screw. If the mixture screw is closed too much it won't be getting enough fuel and cause it to feel rough, cough or misfire. Opening the mixture screw to the correct point will improve this.
If this happens while the engine is running down with the throttle not quite shut, then the big number of the pilot is too big. If the small number was too small it would run bad on the way up.
If it is happening at mid throttle then it could be almost anything but on this set up, probably a base gasket air leak.
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Post by RWS74 on Nov 29, 2016 12:49:06 GMT
Thanks PXGURU, sound explanation. Will let him know. All the best,
Rws
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