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Discussion Starter · #1 ·
So...I've got 2 brand new just out of the box 930's on a 70 Bonneville 650 that's running WAY too rich and fouling plugs like crazy.
I've got the air screw (throttle stop I guess its called) just nudging the sleeve up & adjusted the fuel inlet screws back (from being cottomed out) almost a quarter turn)
It idles without stalling at right around a grand but is just WAY too rich.
I quess my question is, what'll happen if I move the little clip on the needle in the carb up or down a notch?
Right now its set on the middle notch but to be honest, I'm not sure which way does what.
Also, I guess to be as descriptive as possible, the main jet is a 220, the needle jet is .106 and its got short velocity stacks.
Any help is, as always, appreciated.
Thanks.
 

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Try to move the needle clip up, so that it actually moves the needle down. For some reason I'm thinking the 930 is too big for a stock 650 Bonnie. Did you buy those based on manual recommendations?

You might have to rejet.
 

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Richie said:
So...I've got 2 brand new just out of the box 930's
That's enough info for me right there.

I have YET to see a set of new Amals come with the float height set correctly. And I don't mean a little off, either. The last set I got (two weeks ago) had the float height set so high it wouldn't close the needle when the bowl was screwed to the body.

If you haven't set it on an Amal before, it's pretty simple.

Rather than bend a tab on the float like with most for-HD carbs, you adjust the height on Amals by moving the needle seat in the bowl. Use a drift or a piece of rod to LIGHTLY tap the seat into the correct position. The correct float height is noted in the book, but in general the lip that's farthest away from the tab should be about 1/32" below the bowl lip when the needle is close. Easiest way to check that is to hold the bowl upside down while holding the pivot pin in place and seeing where the float comes to rest.

Jason
 

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JasonMcElroy said:
That's enough info for me right there.

I have YET to see a set of new Amals come with the float height set correctly. And I don't mean a little off, either. The last set I got (two weeks ago) had the float height set so high it wouldn't close the needle when the bowl was screwed to the body.

If you haven't set it on an Amal before, it's pretty simple.

Rather than bend a tab on the float like with most for-HD carbs, you adjust the height on Amals by moving the needle seat in the bowl. Use a drift or a piece of rod to LIGHTLY tap the seat into the correct position. The correct float height is noted in the book, but in general the lip that's farthest away from the tab should be about 1/32" below the bowl lip when the needle is close. Easiest way to check that is to hold the bowl upside down while holding the pivot pin in place and seeing where the float comes to rest.

Jason
and if that doesnt work - rejet.
 

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You adjust the richness of the mixture up to a quarter throttle by changing the circlip position on the needle, and by using the adjusting screws. Move the circlip up on the needle to lean out, down to make richer. Anything above a quarter throttle is controlled by main jet size. If the main jet is way too big, then you probably won't be able to get it lean enough. Definitely check float level as well...as suggested by Jason McElroy.

930 Amals (30mm) were the factory carbs for a '70 Triumph.
 

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Discussion Starter · #7 ·
You guys are great!
Thanks for the info.

Looks like yet ANOTHER weekend spent taking carb apart.
I'm gonna start using snaps.....or velcro!

Thanks again!
 

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throttle positions for amals

throttle positions and what effects the mixture;
shut to 1/8 =idle mixture,
1/8to1/4 throttle it is the cutaway on the slide that controls the mixture ,
then 1/4 to 3/4 it is the needle ,
then3/4 to full is the main jet
the main jet effects everything so get your jetting correct first
hope that helps
 

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You should start with 190 main jets. 220's are for hopped up big bores and the like. Remember stock jetting for a 930 carb for a TR6 (feeding both cylinders) is 230. So you are way over jetted.

Re-jet to 190 each carb and lave the needle position in the middle notch.

Richie said:
So...I've got 2 brand new just out of the box 930's on a 70 Bonneville 650 that's running WAY too rich and fouling plugs like crazy.
I've got the air screw (throttle stop I guess its called) just nudging the sleeve up & adjusted the fuel inlet screws back (from being cottomed out) almost a quarter turn)
It idles without stalling at right around a grand but is just WAY too rich.
I quess my question is, what'll happen if I move the little clip on the needle in the carb up or down a notch?
Right now its set on the middle notch but to be honest, I'm not sure which way does what.
Also, I guess to be as descriptive as possible, the main jet is a 220, the needle jet is .106 and its got short velocity stacks.
Any help is, as always, appreciated.
Thanks.
 
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