Pilot screw adjustment

G'day,<br /><br />I have a 50HP Yamaha (50DETO) and I want to tune the carby. According the the Clymer manual the carby should be stamped 62X00 with a 130 main and 62 pilot adjusted to 15mm float and 1.75 pilot screw. My carby is stamped 6H511 ED20 with a 135 main and 62 pilot. According to the yamaha parts site my carby should be 6H511 with 135 main and 60 pilot.<br /><br />My carby was set to about 14mm float (measured on side at maximum) and 2.25 pilot screw.<br /><br />When warm the motor can flat spot or stall on accelaration even after cleaning the carby spotless. I have now set the float at 14mm and adjusted the pilot screw to 1.75. I have yet to take it for a long run and am unsure of what settings to use since the manual does not seem to match my carby.<br /><br />Does anyone know what settings should work best?<br /><br />Thanks,<br /><br />Ian

Re: Pilot screw adjustment

start with the yamaha settings and work from there. the flat spot is most likley incorrect cam follower adjustment. adjust the cam follower to pickup very soon after throttle cable movement. throttle valve to timing advance sync is important, thats where the link occurs.

Re: Pilot screw adjustment

Thanks for the reply Benc,<br /><br />When you say Yamaha settings do you mean as per the Clymer manual?<br /><br />Originally the motor was suffering strange performance where it would run all day on WOT but at say 4000rpm it would slow and near stall after a few minutes but would work fine if backed off and reaccelerated. At that time I checked all linkages and they seemed fine. With hindsight it did not have a flat spot at that time.<br /><br />Following cleaning the carby the above problem is gone but I assumed it could also be causing the flat spot. Now I think you are right since I checked the linkage marks and at idle it does not even reach TDC.<br /><br />In my manual it shows 3 marks 7ATDC 25BTDC and another I assume TDC. My motor has 4 marks in all. From memory I think the most ATDC was the original idle setting. Does this sound correct? Does anyone know what the extra mark is for?