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Discussion Starter · #1 ·
Working on a 68 cb450 for someone. Have it running and rode it today. Seems sluggish at low speed. Rebuilt carbs new floats. Starts great idles good. I set the pilot screw at one turn out. Will the pilot screw control fuel supply at 1/8 open throttle? Should I turn it out or in? I read turning in makes it richer? Is that so or was that bad info? thanks any suggestion will be arpprecated. thanks
 

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Start with making sure your timing is correct.. then you can dial in the carbs.. new floats.. is their height correct? Are the carbs ballenced and synced?
Points or EI? Has the bike sat or run regularly? Old fuel?
Is this a condition that surfaced from a good running bike or r u trying to get this running proper from being sat up for some time?
 

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Discussion Starter · #3 ·
It is a bike that has set for over 25 years. Carbs were cleaned and left empty. I set the new floats at 20mm the tank was sealed 25 years ago and is clean with new gas. Oil is new. After I got it running with new coils I switched to pamco with advancer timing is spot on set at 1000 rrpm. New stock jets with the new o ring on the pilot screw. Before all this I checked cam timing and the valve clearance and adjusted cam chain. I cleaned the air filters. The exhaust seems to be balanced holding your hands behind the mufflers. I have not drilled and tapped holes for balancing with homemade vacuum gauges
From what I understand the Idle jet controls fuel from idle to 1/4 throttle and that is where my dead spot seems to be. Should I turn the pilots in or out to correct this issue? thanks for your inputs.
 

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Should I turn the pilots in or out to correct this issue? thanks for your inputs.
Yes. That would be a place to start.
A flat spot off idle is usually caused by a lean condition. If the bike is all stock. original airbox and exhaust it should be running perfectly. You mentioned it was running before you installed the Pamco ignition, how was it running before you installed the Pamco ignition? Did this problem start after installing the Pamco ignition?
TOOLS
 

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^^^^+1^^^^
I recently was informed by a shop that recommends Pamco EIs ... install it a "full advance" (both cylinders)..
If you have them and they are in good codition.. install the points system, get it running proper.. then install the Pamco
 

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With the engine fully warmed up and idling, the pilot screws should be adjusted to the spot that results in the highest idle. If everything is working correctly, you will hear the idle either rise or drop a bit as you turn the screw in or out. Adjust each carb in the middle of the range that produces the highest idle. Do this for both carbs and then adjust the idle speed screws (not the pilot screws!) as necessary to return the engine to the proper idle speed.
 

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With the engine fully warmed up and idling, the pilot screws should be adjusted to the spot that results in the highest idle. If everything is working correctly, you will hear the idle either rise or drop a bit as you turn the screw in or out. Adjust each carb in the middle of the range that produces the highest idle. Do this for both carbs and then adjust the idle speed screws (not the pilot screws!) as necessary to return the engine to the proper idle speed.
And make sure you feel the exhaust pressure to ensure the idle is the same on both sides. Also do this with the throttle open a bit, to make sure the throttles open up the same. That is, if you haven't added vacuum ports to do this more accurately.
 

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Discussion Starter · #8 ·
Its what I did put new condenser and coils in and got it running then ran into the carb problem with a bad float. After I got the carb working I installed the pamco. Did not want two problems to deal with. I dont understand when you say install it a full advance both cylinders?
 

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Discussion Starter · #9 ·
I will put the timing light back on as it has a good tach and do what you suggest. Will post when I get that accomplished.
 
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