Altitude Jetting and Amal Premiers

I am at 5800 ft altitude, my newish Premiers came with stock settings with the needle in the middle of 3 notches.

Just curious what you all who live at altitude have done to your Premiers' jetting if not leave at stock settings?

How did you get your plug reading? Was it with a wide-open throttle chop? If not, you'd be surprised just how much these bikes rely on the idle/pilot jet for general riding. You could try dropping the pilot jet size and see how that affects things.

Nathan

1up3down said:

I am at 5800 ft altitude, my newish Premiers came with stock settings with the needle in the middle of 3 notches.

Just curious what you all who live at altitude have done to your Premiers' jetting if not leave at stock settings?

Click to expand...

Set the jet needle where is runs best off idle without any hesitation when you slowly roll on. To adjust for altitude you should be going smaller on the main jets as there is less air" up there". When outside of your altitude not worry about jetting. My home is at around 300ft above sealevel, but I don't worry about jets on Sonora Pass once a year when visiting the Sierra passes.

If you are operating the bike at high altitude, the carburation is likely to run slightly rich. If you lower the needles in the carbs and the motor does not cough as you change up and down through the gears while traversing a winding road, you are probably still on the safe side of too lean. For most of your riding, you will not be using full throttle. Plug readings are usually only relevant to full throttle operation, so you can have the situation that you might ride for long distances with jetting that is too lean and not find out until you cause damage. If your motor coughs while you are riding the bike, stop and raise the needles one notch.