Carb Spitback Help??? its getting to me now.

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sunrisemac
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Posts: 47
Joined: Mon Oct 06, 2014 10:25 pm
Main scooter: Lambretta GP150
Location: Dear Old Sussex by the Sea
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coaster wrote: Tue May 06, 2014 10:28 pm When you say you drained the tank, would it be likely that there was still some residue left in the tank? Maybe the water sits on top of the fuel and some got left in the tank? Just thinking out loud here, oil does emulsify when it's mixed with water and air.
I agree that it loks like there's water in the fuel mixture, modern fuels with the dreaded ethanol don't help ;)
johnny650
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Posts: 395
Joined: Wed Oct 12, 2016 10:18 pm
Main scooter: lambretta 64 li 150 Special
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final issues fixed scooter starts and runs really well .

The final 3x issues were carb related (Jetex 22)

First I had not fully seated the carb on the manifold so there was a slight air leak along the gaps in the plastic insert between the carb and the manifold. The reason for this was because if the carb was fully seated the throttle was snagging on the petrol tap joint making it difficult to turn the petrol on and off and also to operate the throttle.

I now use a small block of hardwood (Teak) and a hammer to make sure the carb is fully seated.

Second issue was air-locking in the fuel line. if you don't use clear fuel hose you'd probably never see if this was happening.
I think this was due to 1. the fuel hose having a sagging loop below the fuel bowl and 2. lack of pressure from the fuel tank due to low fuel level and maybe a distorted fuel tap .

once I had removed the fuel bowl and allowed the fuel to flow from the tank to the fuel bowl it cleared the air and the scooter started 2nd kick on choke no throttle and no air filter. I replaced the foam filter and it runs really well very strong acceleration .

The other issue was insufficient fuel at starting and idle and increasing the mixture screw to 3x turns out together with the other corrections sorted the non starting problem completely.
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