389/689 monobloc

dynodave

dynodave

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May 28, 2003
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I have finally allotted myself some norton play time after a 4 year break. I was sorting out parts for the different motors and found I am short a set of 389/689 carbs for my 66 atlas. My 63 and 65 engines work on 389/chopped 389 and I'm all set with those.
I finally figured out the air cleaner differences between the two monobloc styles of carbs.
389/C389 left and 389/689 right. Difference being 389/689 has two fuel banjos to accomodate instead of just one see different dimpling of body here:
http://atlanticgreen.com/images/389689airfil.jpg

My 68 Dunstall Atlas uses 32 mm concentric's. Originally it did not have an air cleaner, but I will remedy that before it goes back on the road.

Any one have a spare set of used rebuildable resleeveable 389/689 -236 or-237or-241... they can part with?
thanks
Dave
 
Chopped amals? lean the bike over one side and it revs up, lean it over the other and it cuts out, the carb with the float is to far away from the other.
Twin concentrics work better.
 
john robert bould said:
Chopped amals? lean the bike over one side and it revs up, lean it over the other and it cuts out.
Click to expand...

Keep it approximately upright while stationary.
 
Triton Thrasher said:
john robert bould said:
Chopped amals? lean the bike over one side and it revs up, lean it over the other and it cuts out.
Click to expand...

Keep it approximately upright while stationary.
Click to expand...

In a lean, the fuel surface tilts to remain normal to the vector sum of the gravitational force, and the centripetal force.....similar to the way the ball in an aircraft turn and bank indicator remains in its straight and level sector when the aircraft is making a proper turn.

The end result is the fuel level remains in proper relationship to the carb jets in a lean, or stationary upright.

slick
 
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