Waterbox jet size?

[rotaxrule1]

Hi guys,

I am trying to figure out the exhaust setup on my xp, I think I am pretty close now. I have installed a coffman rec pipe, ocean pro flame arresters, and have a stock waterbox with the water reg removed. I am trying to figure out the routing for hard jetting my water system.

Basically I have the stock t fitting between the pump and head that leads to a Unjetted plastic t fitting that routes to my manifold that has its own jetted t fitting, then I have the other end going to my jetted t fitting, which goes to my waterbox and tail cone.

My question is what size jet am I supposed to use in these? The documentation from coffman says use a 65 main jet, but that is awe fully small, and various posts online talk about using 165 to 190 jets. Does anyone have any experience in this area? I have my stock 142.5 main jets I can use, is that a good starting point?

Thanks in advance

 

[Matt Braley]

Yeah 65 is not much at all for passing water. Usually a 65 is used on the fuel return on aftermarket carbs. I would start with the 142.5 jets that you have and put one in the wb and one in the stinger fitting(tail cone). See how it performs and make sure the wb is not getting too hot. Use inline fuel filters before the jets so they don't clog and burn your coupler and rear riser exhaust hose.

I can't picture your water routing yet. It just seems like there are too many T's in there. From the stock T on the incoming cooling(1/2"X1/4"X1/2") line I would run a T(three way 1/4" barbs) and use the two barbs that are left to feed the headpipe and the wb. I like to feed the stinger with a fitting screwed into the overheat sensor hole. You may want to hear the continuous beep if your getting hot though so I spose that is where another fitting is needed.

I don't think one 1/4" fitting is going to do a great job of feeding three. You may want to put another 1/2X1/4X1/2 in the incoming line.

 

[rotaxrule1]

Hey Matt,

Thanks for the info. I have attached the diagram from coffman, the way they have the t fittings illustrated was how I was trying to set it up. But didn't realize I may have a flow issue (does make sense though) so I may grab another large t fitting to t from the incoming hose again. I'll try the stock jets and see how she does, thanks again!

 

[rotaxrule1]

Hey Matt,

Thanks for the info. I have attached the diagram from coffman, the way they have the t fittings illustrated was how I was trying to set it up. But didn't realize I may have a flow issue (does make sense though) so I may grab another large t fitting to t from the incoming hose again. I'll try the stock jets and see how she does, thanks again!

View attachment 23965

 

[Matt Braley]

I've never seen that diagram before....nice! I would start like they have it then. I wish they listed jet sizes. Your gonna need a good tach so you you can determine what is what. Smaller jets dry it out and create more revs but you don't want anything too hot under there. Start large and work your way down.

 

[rotaxrule1]

I've never seen that diagram before....nice! I would start like they have it then. I wish they listed jet sizes. Your gonna need a good tach so you you can determine what is what. Smaller jets dry it out and create more revs but you don't want anything too hot under there. Start large and work your way down.

Sweet, I'll start there then. I actually bought a tach off an old jet boat and soldered a resistor in the line, then I am putting it by the DESS key so it looks like it would have came with it. It will only be as precise as the crappy oem gauges, lol. But should give me an idea of rpms. I poked the stater wire and powered it up the other day and it looks like it will work nicely. Anyway, I'm excited to run it this year with these mods and the tach, should be fun as long as I don't blow it up.

I hear I need a rev limiter, but man the way the thing sounds when the pump comes out of the water, I swear it already exceeds the rpm compared to my gsx and gtx, so I will be curious to see what the tach says.

 

[Matt Braley]

I have an extra rev limiter reasonably if you need it. Another option would be a taller prop to try and make more speed. I think they recommended a Solas X1 with that which is a lot taller than the stock impeller.

 

[Minnetonka4me]

You absolutely need a rev limiter. The whole point to modding them is to gain a few extra 100 RPM on top which is more speed.

Matt also brought up an important point...you must run a filter or strainer. I run strainers.

I have a brand new X-1 prop if anyone needs one.

Oh...and you wouldnt need to worry about heat with my new silicone exhaust hoses!! You could run it dry! Deposit needs to be in by march 1st.

 

[rotaxrule1]

Thanks guys, I will keep the prop and rev limiter in mind. I guess I wanna try without first and see where I hit, because I seriously have never heard the limiter kick in on this one, so I may not need one. I can go out there and start it and it revs all the way to a point where I cringe, lol. I know this from when I blow the water out of the exhaust on the ramp, and when I hit jumps, it never backs itself off. And now I will have a tach to see around where I'm at. My gsx, and gtx definitely hit it past like 7000 or 7200.

There is no reason it would already have an aftermarket rev limiter, because it has been totally stock, so it is a strange deal. I'll keep you all posted once I can finally dip it in the water.

 

[blackNyellow787]

Nick what kind of strainer do you run and where could one be purchased?
I'd guess there are probably different brands & styles available?