Outboard Jet Reverse Problem

[otterbfishin]

I run a 16x60 tunnel modified jon powered by a 50hp Honda 4 srtoke with a jet. My problem is that the jet does not operate properly in reverse. It will work a little at idle, but if rpm's are increased it seems to cavitate (?). The engine height is correct and the linkage adjustment for the bucket is also to factory specs.<br />Does anybody know of a modification I can make to the bucket to give more reverse power?

 

[Bondo]

Re: Outboard Jet Reverse Problem

Jet Drives are Famous for having Lousey Reversing capabilities.......

 

[rodbolt]

Re: Outboard Jet Reverse Problem

what bondo says, plus in a tunnel the problem is compounded by your backing the jet intake into your turbulence in the tunnel.<br /> jets dont like areated water at all.

 

[otterbfishin]

Re: Outboard Jet Reverse Problem

So, directing the flow at a deeper angle by bucket mods might wotk? Anybody?

 

[Chief101]

Re: Outboard Jet Reverse Problem

I'm assuming that you have the same outboard jet pump as mine, and if so I don't know what modification to the bucket you can do. It just sounds like you are running the engine too shallow. In reverse the whole jet pump should be submerged, and if not will not pick up water and that will cause the same problem you are having. Reverse isn't great with an outboard jet, but it is positive. The tunnell hull should have no effect in reverse, only in forward.

 

[otterbfishin]

Re: Outboard Jet Reverse Problem

hief 100,<br />The engine is at the position the dealer set it at. I tried to lower it "one notch" which was about 1", but the foot of the jet was submerged and the top speed dropped considerably. I raised it back up to the dealer setting. Could be I need to drill holes 1/2" below the current setting? I don't know. I don't want to loose any top speed.<br />Thanks,<br />otterbfishin.

 

[Bondo]

Re: Outboard Jet Reverse Problem

Could be I need to drill holes 1/2" below the current setting? I don't know. I don't want to loose any top speed.

Could Be....................<br /><br />Or,.......... It Could Be,..<br /><br />That you'll have to accept the fact that Jet Drives Don't Reverse Very Well................

 

[Chief101]

Re: Outboard Jet Reverse Problem

Otter, jets and tunnels don't get along well, but reverse should still work ok. If the gate is all the way up when you push into reverse, and you are deep enough to get good speed when in fwd, I don't know what the problem would be. You might take the bucket off and make sure the casting is not defective. just a thought

 

[Chief101]

Re: Outboard Jet Reverse Problem

On second thought, the tunnel hull may allow the engine to be to high to get good performance in reverse. Here's a page with some pictures of a correct setup for a jet on a nearly flatbottom hull. If your engine is setting higher than that you will have the problem you describe. Chief<br /> http://sites.state.pa.us/PA_Exec/Fish_Boat/boatcrs/jet/jetboard.htm

 

[otterbfishin]

Re: Outboard Jet Reverse Problem

Chief 100,<br />Wow, that site is great! I think my questions have been answered. In my case I will have to install a transom jack. If I can lower the motor when backing off the beach the jet foot will be submerged enough to get good traction and not cavitate. Then when powering up in forward I will raise it back up to achieve the least drag for the conditions giving me my maximum forward speed. Now to research transom jacks and costs?? The other thing I gained from that site is that I'm now convinced that I do need a stainless impeller to gain as much advantage over load and displacement as possible. As I might have mentioned before my boat goes great with just myself and possible one other, but really slows down with three on board. A 16 to 25 percent increase in thrust would help to reduce this problem.<br />Thanks again Cheif 100,<br />otterbfishin

 

[Chief101]

Re: Outboard Jet Reverse Problem

http://www.wooldridgeboats.com/jets.htm#outboard <br />These are the guys that developed the SS impeller for outboard jets. Go to the "contact us" page and either call or email them They will be there to help you with any more info or parts you might need. They should have the best price on the ss impeller you need. Chief