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Initial Startup really bad idle - Help Needed

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paulbaker1954:
All back together and ready for MOT now BUT..............really poor idling problem  :( :( :(

Symptoms --- starts OK even from cold but sounds like a tractor  >:( >:(  moving choke doesnt seem to make a whole lot of change. Also I noticed that adjusting the pilot air screws doesnt seem to induce any change in engine note but to be fair this is the first time I have worked on a four and I was only moving the screw about 1/4 turn either way. SO I am not sure really what I should be listening for here.

Once warm she sounds better but still a bit lumpy, blipping throttle off idle to say 3k RPM sounds really good

What I have done ........


A) Carbs all cleaned out including all jets removed and cleaned and all appear clear. All jets are original Keihin and fitted with new O rings.

B) Carbs have been balanced

C) New points and condensors fitted and timing strobe checked

D) New intake boots and no air leaks detected

E) All pilot air screws set unitially at 1 turn out


Overall it sounds to me like overfuelling at idle the only thing I have NOT done is removed the pilot air screws and cleand all their orifices


My plan as I really dont want to take the carbs off agaiin

1) Recheck timing with strobe

2) Recheck float heights and fuel levels using "manometer" tubes

3) Remove all pilot jets reclean and squirt a ton of carb cleaner in the pilot air  screw holes


Anything else anyone can suggest ?

Bryanj:
May sound like a daft question but you haven't left anything under the seat then shut it have you? Also check that the advancer is working Plus Idle is normally at about 1100 RPM

Sgt.Pinback:
Did you check the valves? Spark on all pots?

paulbaker1954:
nothing under seat and yes firing on all pots

As I said runs great at higher revs

Johnwebley:
try checking plug caps,

 as they get older the resistance increases,

 

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