115 HP Merc

[Crazy]

Well guys took my boat out today , after the over heating and changing of the water pump . Runs great . Oh ya the boat is a 77 Formula 18 foot fiberglass , After it is good and warm and I put it N it will stall ??? idel is way low , how do I fix this . I done a WOT test and no Bog off the line and it plained out fast , top speed was 32mph at 4800RPM's , That's a little low ... Prop #'s are hard to see , I'll have to scrub some paint off . The boat doesn't have power trim , it is Man and I have it set in the 2 hole of 5 , I'll try #3 next time . What do you guys think

 

[emckelvy]

Re: 115 HP Merc

This is an inline, yes? If it doesn't bog on acceleration, it's certainly not too lean! <br /><br />Maybe all you need to do is bump up the idle speed stop a bit to get a stable idle in gear. <br /><br />Or, on the off chance it's a bit rich (especially since it does this once it's good and warmed up), you might try leaning out each carb 1/8 of a turn (clockwise). You'll know if you go too lean 'cause it'll bog. <br /><br />But it definitely will get a bit fussy if too rich. You won't notice when it's cold, but as you have experienced, when it warms up it won't idle well.<br /><br />And you are definitely overpropped, that motor should be spinning up to at least 5500 rpm, preferably higher. <br /><br />You'll likely find an increase in speed with the lower-pitched prop, as the motor produces much more HP in the correct rpm range. <br /><br />If your hull responds well to trim, it'll do better with the tilt pin in the 3rd hole.<br /><br />HTH and let us know how it runs............ed