95 40/30 yamaha jet tuning issue or pump.

[muffintop]

[FONT=helvetica, arial, sans-serif]I got a kinda serious issue im facing that you all might have experience with. I finally have had the time to take out my jet sled on the water after buying it almost 3 months ago and although it has great compression and the impeller looks ok. i could not get it up on a plane. I put everything heavy towards the front and even used a 3ft tiller extender so that i could stand in the middle of the boat. nothing. my boat is a 15ft valco with a 40/30 95 yami. Im wondering if my pump sits to far in the water or if my impeller is really out of shape. maybe my yamaha is not tuned right? idk where to start.[/FONT]

 

[mphelle8vld]

Photos of how the pump lines up with the bottom of the transom would help. I would recommend purchasing something similar to this: http://www.ebay.com/itm/New-Digital...nes-/331223584733?hash=item4d1e76cfdd&vxp=mtr to help troubleshoot.

Jets are very sensitive to weight, what are you carrying in the boat?

 

[muffintop]

I checked the gaps on the spark plugs and some where a bit off so i re adjusted them. going to take the boat out later. Also a friend told me to check how much the throttle opened when i gave it full throttle and i feel that it did open almost all the way, but there is still a little bit that could open up even more. with out a tack i could not say if my motor is taking to high or what. generally with a 2 stroke you don't wide open them since the powerband is lower. but This knowledge only pertains to my use with ATV's a bikes. the grate is a bit lower than the bottom of the boat. but only by half an inch if.

Here is a picture of throttle linkage when the tiller is set to 0%

here it is at full throttle,

 

[mphelle8vld]

I would still recommend the tach to monitor the health of the motor, it should spin that pump around 52-5300rpm. First I would move the trim adjustment pin to the middle or lower hole and test again, in the current position, you're wasting a lot of thrust trying to lift the bow of the boat.

Wanted to add that you should remove the plastic carb cover (4 screws) to see if the throttle plates are fully open (horizontal) at full throttle.

 

[muffintop]

So i took the back carb cover off and the two bottom cylinder looks to have a bit of gas residue inside even though when i put the motor away i ran it dry, or so i think. also my spark plugs seem to be a bit wet. mind you im a novice about boats.
I adjusted my angle to the max, and i have another wonder. could the bottom rib that is like 5 inches from the stern cause caviataion?

 

[mphelle8vld]

Take this photo again with the trim adjustment pin in the middle and then in the bottom hole.

 

[AJ168]

Two good jet references- http://www.leeroysramblings.com/outboard_jet_maintenance.htm and http://fishandboat.com/anglerboater/1999/sepoct99/jetboard.htm

I saw a huge increase in performance of mine by having the impeller shimmed properly, and also by keeping the leading edges of the impeller clean.