yamaha 40hp 2T help please

[nw04jen]

Hiya

Have 90s 40hp 2T - starts on the button first time with choke lever up....as lower it to what would normally be idling - engine splutters and conks out - if keep lever up a little more splutters almost like a cough every few seconds - not sure how to describe it...just wondering if anyone had similar and knows remedy. I intend to alter the throttle cable slightly to increase idle but not too much- just wondering what the 'cough' actually could be?

TIA

[beamishken]

Originally Posted by nw04jen

Hiya

Have 90s 40hp 2T - starts on the button first time with choke lever up....as lower it to what would normally be idling - engine splutters and conks out - if keep lever up a little more splutters almost like a cough every few seconds - not sure how to describe it...just wondering if anyone had similar and knows remedy. I intend to alter the throttle cable slightly to increase idle but not too much- just wondering what the 'cough' actually could be?

TIA

Carbs will need a full strip & clean, preferably in an ultrasonic bath but alternatively a strip & spray through all the jets & orifaces with carb cleaner will do the trick

[nw04jen]

Many thanks...will begin tomorrow!

[nw04jen]

So cough splutter was solved easily with altering the mixture screws on the 3 carbs all back to 1 3/8 ish open - cleared immediately and idles perfectly - WOT cuts out so am guessing still need to strip and clean carbs as likely main jets are blocked