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front card phf 32 COUGHING and idle difficult to set

Posted: Wed Jul 27, 2011 9:24 pm
by maxmar
HI

i think i have a problem on my 750 gt . when engine is cold the front carb is coughing when accelerating at low rpm . on the other hand even when engine is hot it s difficult to have a good engine idle though both idle screw on the carbs are at the maximum. and richness is set properly.
i m wondering whether the carbs themselves are to old so there is a small air leak somewhere so that the idle circut is not working properly.
at high rpm the engine is just working perfectly from 2500 rpm.
what should i look at .? idle jets are 60 carbs phf 32
MAYBE fuel level in the carb?
any help appreciated
cyrille from toulouse france.

cough

Posted: Thu Jul 28, 2011 3:24 am
by Lumpy
Maybe sucking air through the front carb manifold gasket?? Although I`ve never tried this myself I`m told vacuum leaks can be detected by spraying Aerostart (cold starting aerosol aid for worn engines)at or around the manifold gasket and watching for a raised idle. Watch out however the stuff is EXTREMELY flamable and should probably only be used while the engine is cold.
Failing that I would perhaps be looking at ignition timing. I beleive the old round cases were points type ignition. My Duc`s are all square cases and don`t use points...............kinda wish they did some times. Although not that reliable or efficient they are easier to fault find and are reliable enough if you keep them in fine fettle. Good luck.

RE

Posted: Thu Jul 28, 2011 3:37 pm
by maxmar
YES IT is a good idea .these gaskets look quite old and might be cracked a little bit . last time i found that i could thighten the nut . pobably i should change them and see what happens. thanks

re

Posted: Thu Jul 28, 2011 3:38 pm
by maxmar
and also i have a dyna coil on my duc and it s been set 1500 miles ago.