Stumped. Slow boat,,,,

[rennen]

I cant figure out why the heck my boat wont get up to speed. I found out that I was running on one cylinder a few days ago, so I changed the head and spark plugs to fix. Then I addressed the issue of my cavitation plate being too low by raising the motor 3 inches. Progressively the boat is getting faster but it is still really slow. At WOT I can hit about 15 mph by myself and MAYBE 10 mph with a passenger. The boat is so ridiculously weight sensitive.<br /><br />I will decarb the motor tomorrow and pull the prop off to check if it is spun. From the looks of the prop, when it is still attached, it looks fine.<br /><br />What could I possibly be missing? Any insight is appreciated, as I would like to overtake canoes sometime this month.<br /><br />Thanks,<br />Sal

 

[umblecumbuz]

Re: Stumped. Slow boat,,,,

Hi Sal,<br /><br />Love the canoes bit! Presumably they'd be going upstream while you're heading downstream?<br /><br />What motor? What boat? What WOT figures? What prop?<br /><br />Even some of this information will help the experts here to reach the ballpark.

 

[rennen]

Re: Stumped. Slow boat,,,,

Ha ha.. Thats the third post that I forgot to post that vital info... I thought you all would just assume that I have a 1963 Evinrude 40hp Selectric Shift, on my 1957 14ft Rockholt Utility Runabout. Just a little wood boat with a Mahogany Deck. WOT??? I think about 6k 7k, but I couldnt tell you cause I dont have a tach. Prop.?. The black one that came on the motor (i think about a 10inch but pitch ???<br /><br />Sorry to be so vague but I simply dont know the rest of the info. This is my first boat and I am on my "Broke college student budget" so luxuries like tachs and speedos come with time.<br /><br />Thanks =) Sal

 

[lark2004]

Re: Stumped. Slow boat,,,,

Sal,<br /><br />You really should just keep all this in the original post.<br /><br />That way every one can see what has been done, and see if something has been missed.<br /><br />At the moment, you now have three post going, asking the same question.<br /><br />Now, as to the WOT rpm's for these motors, Don't go over 5000 rpm. If you do..... at least the pistons are facing the back...<br /><br />now, are you sure that you have spark to both cylinders all the time? <br />Mabye you have problem in the vacume cut out switch. <br />It should be grounded through the switch on top off the block, above the exhaust cover. this only provides ground at low rpm. That way the cutout switch won't affect high rpm running. It is only there to prevent rpm runaway when the throttle is closed(it's a habbit of the bigtwin).

 

[rennen]

Re: Stumped. Slow boat,,,,

Gotcha Lark,<br /><br />Now consolidated and will reply only to this post.<br />Thanks