Evinrude 140 Idling and Hydrofoil

Update: I just ran my boat after having my prop reconditioned, see email below:


I am glad I found this site, you provide some great insight.

I have a 1988 18’ Stratos Bass boat with a 140 Evinrude (model E140TLCCM), with a StingRay hydrofoil/stabilizer bolted on, and a Raker 13.5” x 20 prop. At WOT it runs approx. 5600 RPM, yielding only 46 MPH (by gps). I have had this outfit approximately 2 years. I have no complaints about the outfit, as I got a great deal through a friend on it. Supposedly the unit was entirely rebuilt by the previous owner (which I firmly believe, judging by the condition when observed with the cover off). It seems to have a good hole shot (I have nothing to compare it to), and good top end. The only fault in performance is that sometimes it “starves” for gas at idle, and may sneeze and stall, particularly when idled for a few minutes.

I have two question areas:

Idle speed running:

Is there anything that can be done for the idle speed gas starvation? All fuel lines are good, no air leaks, etc., and I always run a fuel line filter and marine fuel stabilizer/cleaner (btw, are all stabilizers created equal? I use Valvoline, available at my local Wally-World). It has been a number of years since I owned a boat before this one (this is actually the largest outboard, since the 1963 75 HP belt drive distributor Johnson I owned in the late 70’s). I have also noticed that my brother-in-law’s new 90 HP Saltwater Merc runs rough at idle, and can show similar symptoms. Is this typical to a large number of 2 stroke outboards?


I tried running with it removed, but it was slow to plane (I assume ventilation), and had uncontrollable “porpoising” at higher speeds. This boat is rated for 150 HP. Does this mean the engine is too heavy for the boat? Would a different prop cure/help this so that the hydrofoil is not needed? Are all hydrofoils created equal? I did some checking on Raker prop sizing, and it appears that the 13.5” diameter is not the norm for this outboard. Would an extra inch of pitch help here? Is this the appropriate top speed for this outfit? It almost feels like the hydrofoil could be slowing me down……is a jack plate in order, or best well left alone?




Stick with the prop you have. The idle just needs to have the idle air bleeds sized down. This will cure the idle. Hydrofoils are experiment only at best. You would have to try a bunch to see any differences.




Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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