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Heres something you don't see every day

A Close inspection of the clearence, and condition of the impellor and housing might be worth a mph. Smoothing, and knife edging the intake grate can help also. Make sure that the reversing mechanism does not hang down into the jet stream when in forward. Due to the direction the impellor spins, the pump may like water to come in at a certain direction. You may see an increase in forward velocity by slightly turning the powerplant either right or left, at speed. I predict 50 mph. Covering up exposed areas of the interior can be good for a mph or two also.
 
Bill Gohr said:
When you put a jet pump on the boat, the pump needs to be as close as it can be to the boat and still turn, as well your boat will never work well with it because it is a V bottom, thats why it is so trim sensitive. The pad will protrude down below it or above it, no matter what you do, it will arrate the pump. They work the best on a flat bottom boat with the intake about 1/4" below the bottom and negative trim.

Also, when we built V6 jet pump outboards, we had to take compression out of it, not add it, on decelleration, the motor detonates so bad it sounds like it has marbles in it, if you look the OMC 105 jets have looser heads to correct this issue, one of the reasons they were called 105's.
Click to expand...


It works reasonably OK. The compression is low to be sure but it is able to maintain a half decent top speed. It has to be on a Jackplate to work though . No possible way to get that motor high enough without one. Otherwise it would be hanging 8 inches into the water. In any case it was a fun experiment . Now I'll bolt some 34 CC heads on with a standard lower and it will run just fine. Only crappy part will be getting the shift shaft in there.


Best thing is that it has a 105 HP sticker on the midsection.
 
Bill was 100 % spot on. I changed the lower and with a 23 pitch prop on a 2:1 lower it would barely get out of its own way off idle. Ran OK to 65 MPH top end but pretty sluggish getting there Checked the compression and found 90-95 psi all around. Pulled the heads and they were 47 cc on a 2.0 liter. Picked up a set of 32 cc heads and those should liven things up a bit. Those should put me in the 14-145 ish range and since all I use is 92 octane it should work OK.
 
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