I have learnt a few tricks for centering the jets:
1: When the engine is running, the airflow will naturally
tend to pull the piston downstream, towards the engine.
So when lifting and lowering the piston to check the centering,
gently (I mean less than an ounce of force) press the piston
towards the engine to make sure the needle does not start to touch the jet.
This is more of an issue as the piston shaft becomes worn and allows
a bit of lateral free play.
2: Make sure the choke is off, and the jets are adjusted upwards
at least as far as they will be after the tune-up. I would temporarily move
them up all the way, until they are flush with the base of the venturii.
3: Replace the thin soft aluminum washer between the jet and the clamp nut!
After it is installed, it gets deformed, and if you need to re-center
the jet, the deformed washer will interfere. I got half a dozen of
these washers from Rimmer once, so I would always have some spares.
If you are lucky, you can re-use it once by flipping it over.
Also, don't overtighten the jet clamp nut.
Doug Braun
'72 Spit
At 07:13 AM 6/1/01 , Nolan Penney wrote:
>Yes it's important to center the jet, and yes it's easy to detect.
>
>The best way is to remove the air filter cover, reach in with your finger and
>lift the piston, let it drop. It should fall all the way down, with a solid
>"clop" sound when it hits the bottom. If the jet is off center, the needle
>will make contact and slow the piston down on its decent, sometimes even
>stopping the piston from falling all the way down.
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