Re: Weber carb problem?
As per above but before doing any of this do as Hugh says. Give both carbs a thorough clean.
If these are the standard carbs fitted by factory then they come with the cold start device (choke to the rest of us). Check, then double check that this is working correctly. It is effectively a carb within a carb so if it is not closing properly (little gears open and close an internal sprung valve) then you will be over fuelling and this will make the soot you describe. A common modification was to use a deletion kit to remove this. If this has been done, then again check it has been done properly.
The Weber DCOE has an idle circuit. The idle circuit has VERY thin passages. Make sure this is not blocked. If it is blocked then NO fuel will get into the engine at idle. Another issue you identify. The idle jets are the 2 on the top, under the little round cover, closest to the engine.
The butterflies should be virtually closed at idle, letting in hardly any air. The idle circuit takes over providing the air-fuel mixture. Carb cleaner can be very effective at cleaning these tiny passage ways.
Often people who do not understand these carbs will try to overcome the blocked idle circuit by opening the butterflies. This then creates loads of other problems as you are now exposing the emusion tube holes which control the off idle characteristics. This will identify itself as rich mixture which will also give you the soot.
Float height is also a very important factor. Check this against the manual but usually set to 8.5mm closed, 15mm open giving a stroke of 6.5mm.
Hope this helps.
Originally posted by AdminUser
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If these are the standard carbs fitted by factory then they come with the cold start device (choke to the rest of us). Check, then double check that this is working correctly. It is effectively a carb within a carb so if it is not closing properly (little gears open and close an internal sprung valve) then you will be over fuelling and this will make the soot you describe. A common modification was to use a deletion kit to remove this. If this has been done, then again check it has been done properly.
The Weber DCOE has an idle circuit. The idle circuit has VERY thin passages. Make sure this is not blocked. If it is blocked then NO fuel will get into the engine at idle. Another issue you identify. The idle jets are the 2 on the top, under the little round cover, closest to the engine.
The butterflies should be virtually closed at idle, letting in hardly any air. The idle circuit takes over providing the air-fuel mixture. Carb cleaner can be very effective at cleaning these tiny passage ways.
Often people who do not understand these carbs will try to overcome the blocked idle circuit by opening the butterflies. This then creates loads of other problems as you are now exposing the emusion tube holes which control the off idle characteristics. This will identify itself as rich mixture which will also give you the soot.
Float height is also a very important factor. Check this against the manual but usually set to 8.5mm closed, 15mm open giving a stroke of 6.5mm.
Hope this helps.
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