might be a pain in the arse, but would squirting neat fuel into the carb help with the starting issues first thing in the morning. I take its ok when you have been out and about on the scooter, left it for an hour or so, does it start no problem or still a pain.
gary
vespa t5 tillitson conversion
-
Rich_T
- Dealer
- Posts: 540
- Joined: Fri May 29, 2009 8:07 pm
- Main scooter: Li Special
- Location: Birmingham
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They can also be a bit of a pig to re-start when they are hot. The reason for this is that as the carb gets hot some of the fuel turns to vapour in the delivery chamber and sometimes you get a bit of an air lock. Also a pressure pop off and decay tester is useful for testing these carbs as needle seating is important.
One other thing to note on these carbs, if you buy one with a choke butterfly look out for a large brass screw on the side of the body held in with a red locking compound. This screw is a cover for an RPM limiter. How this works is that there is an additional feed from the fuel pressure chamber to the venturi. This path is covered by a small ball bearing that is kept in pace by a spring. If the carb is vibrated heavily (such as over reving) the ball bearing does not seat and extra fuel enters the venturi over richening the mixture (effectively turning the choke on to kill the revs). This type of carb is not a good idea for scooters, if you get one use it for spares as typically they are used on chain saws.
One other thing to note on these carbs, if you buy one with a choke butterfly look out for a large brass screw on the side of the body held in with a red locking compound. This screw is a cover for an RPM limiter. How this works is that there is an additional feed from the fuel pressure chamber to the venturi. This path is covered by a small ball bearing that is kept in pace by a spring. If the carb is vibrated heavily (such as over reving) the ball bearing does not seat and extra fuel enters the venturi over richening the mixture (effectively turning the choke on to kill the revs). This type of carb is not a good idea for scooters, if you get one use it for spares as typically they are used on chain saws.