Sport Jet inlet guard

[RedBarron55]

I just bought a Hobie Jet Fisherman and it has an inlet guard I have not seen and I wonder if anyone has information on it.
The jet is a Mercury Sport Jet 90
and here is a picture

 

[Cobra Jet Steering LLC]

my guess is someone built that or modified the original one, I know I modify all my intake grates to keep out weeds. I have never seen one similar to yours

 

[RedBarron55]

I finally got my Hobie Fisherman running and it is turning 5000 - 5100 rpm per specs from a 1996 article, but the speed is lower by about 6 mph.
The jet parts look new and have good low clearance and the only question I have is the inlet I have.

This seems to be a kind of loader, but perhaps it pulls in water from the front of the boat in shallower water instead of pulling sand off the bottom.
This sticking down might be slowing the boat down some, but I might be willing to trade some speed for less pickup from the bottom.
Perhaps if I took my grinder and streamlined the bars a little in the front the water would at least go in with less drag.
I tried to remove the screws but they are frozen and will need some heat to get out.
I may try the boat without a grate and see if it makes some difference

 

[Cobra Jet Steering LLC]

Yes putting a taper on the leading edges will help somewhat but I still have never seen any intake grate like that one and I would love to see the parts diagram to see if it is a custom built one as I suspect it is, Top load grates have the deflector above the bars in the tunnel deflecting water to the top of the pump.

 

[RedBarron55]

I haven't found any like it either and I also haven't found a stock grate to replace it with either.
If I can get the thing off I will see if I can streamline it some.
It has to add drag if it doesn't cram more water in than it absorbs in power.
BUT it it keeps the sand and weeds out in shallow water what is a few MPH.
Fairing off the blunt edges can't hurt the above presumed benefits and would help get the water into the pump.

 

[Cobra Jet Steering LLC]

It looks like it hangs down from the bottom of the boat about 2 inches that would concern me . As for loosening the bolts try a hand held 1/2 inch drive impact driver with the proper size tip and a good hammer to smack the driver with after you heat them.

 

[haknslash]

Dang that thing looks like a fish worst nightmare from a jet boat !! I see some fishing line snagged in between the ride plate and intake grate.

Then again there was that one member on here who posted a pic of a big catfish that got sucked up and wedged in his top loader which I'm sure was just fun to clean out on the trailer

 

[RedBarron55]

I have one at another workshop in Mobile.
As it is I managed the wring the head off of the first one I tried.
With the other screws on the jet like the pivots a little heat helped.
(I wrung off one of the reverse bucket pivots too)
And yes it does hang down about 2 " and that is a concern as well, but I haven't found a replacement stock grate yet.
By the way are you familiar with the advance curve on the Force 90?
When I put the CDMs on the engine and the new trigger coil I found the advance a bit more than I expected.
I was worried about too much advance as I advanced the throttle in the water as It went past 30* buy a good bit.
However the timing came back to 30* at WOT.
I assume the extra advance is OK since the carbs have not opened up at that point. Can you tell me if that is correct?
Thanks

 

[Cobra Jet Steering LLC]

I honestly have on experience with the timing on those power heads sorry

 

[RedBarron55]

If I sharpened the leading edges enough on that grate perhaps I could use it to fillet the fish I hope to catch really really fast

 

[Cobra Jet Steering LLC]

Dang that thing looks like a fish worst nightmare from a jet boat !! I see some fishing line snagged in between the ride plate and intake grate.

Good catch I never noticed the line there until you mentioned it. I would personally redesign that plate I believe it will work to feed smaller twigs and other items into the pump and crash into the beach digging up sand if it hit the bottom.

 

[RedBarron55]

I think you are correct in that if you did run aground the thing would make a great scoop to pound sand and debris into the pump.
Anybody got a spare Sport jet intake grate?