1986 120hp VRO sluggish. problem

86 120 VRO new fuel pump, tiiming set, idles well, slow to get on plane, boggs down, once it gets to high speed(4200rpm), its fine. Back down under 3700rpm it falls off and is sluggish to get back to high speed.
Whats wrong??

Re: 86 120 VRO sluggish. problem

Have you tried cleaning the carbs.

I don't just mean throwing something in the tank or squirting something in the throat.

It sounds like you have a clog or two in the low/intermediate speed end of things.

Aside from the main jet (which sounds like it's fine), each of the 4 carb bodies has an air idle jet and an intermediate jet (to the left of the throat) as well as a couple little (internal tubes) that carry fuel "behind" the butterflies on the throttle bodies.

There is also a little channel/hole in the throttle bodies (one for each carb body) that lets fuel bypass the butterflies when they are "less than fully open".

If any of the above is clogged not only is your performance suffering, but one or more of your cylinders may be getting "oil starved" - and that's a really bad thing

Carb kits are fairly cheap for this model (I just rebuilt the carbs on this exact model/year) and the carb bodies themself are one of the easiest carbs rebuild (all the jets are fixed, so only need to be soaked out in alcohol).

Not counting the "soak" is about a 1 hour job - worth doing...

Re: 86 120 VRO sluggish. problem

Thanks for the reply. Re-building the carbs makes perect sense. Thanks for the help. I'll follow up after the rebuild!!!!!