Jet sizes for hard jetting waterbox

[MPower]

What size jets has everyone found to be ideal for a 787 X4 with high compression (pump gas) and jetted carbs with F/As?

 

[glsmohio]

you running stock carbs? 44's i like to be around 250 total

 

[Matt Braley]

140-150 in the waterbox where the water regulator was.
I would not go less then 100 in the mid pipe unless you put a fitting in the stinger. If you do you can run a little smaller in the mid without getting the coupler and rear riser hose too hot.

 

[MPower]

you running stock carbs? 44's i like to be around 250 total

Yep, stock carbs just jetted for flame arrestors. The seadoo racing manual says start with 200 in the waterbox and 150 in the fitting on the pipe. Also, stock pipe, but milled head.

140-150 in the waterbox where the water regulator was.
I would not go less then 100 in the mid pipe unless you put a fitting in the stinger. If you do you can run a little smaller in the mid without getting the coupler and rear riser hose too hot.

Matt, what do you mean 150 in the pipe unless using a fitting?


Overall I am confused because when we did this on Suke's ski he lost 100+ RPM (6790) with 150 in the waterbox and 115 in the pipe. Tried 200 in the waterbox and 150 in the pipe as in the Seadoo Racing Manual and RPMS went back to 6940.

 

[Matt Braley]

That's great that he was able to work it into a good spot. That's a great RPM for a stock pipe.

The stinger location is at the small end of the pipe cone just before the coupler that goes to the waterbox. There is no fitting there but they do cast in a place for to be drilled.

Normally the more that you dry out the pipe the more rpm you get. Adding water when taking off helps it pull through the mid range but then it limits rpm at wot. If you can find better rpm by adding water that is great because things are running cooler and larger jets don't clog as easy.

 

[MPower]

Matt, would different locations for the jets have an impact.

Seems some put both jets in the T fitting while some put a jet in the fitting on the waterbox and one in the fitting on the pipe? Would that make any difference?