SXR Issues

[112motorsports]

I have an SXR with a wet pipe, ADA head and flame arrestors on it, and it will not run worth a darn down low. I have have to keep the throttle damn near half open to get the thing to get up on a plane. Once it comes up it runs like a top. It seems to me that it is running way too rich on the bottom end. I bought it from a guy who ran it in the ocean and the cabrs we full of salt so I bought a used set off a guy and they are mint. I thought maybe it was the check valves in the carbs but after switching them out I have pretty much ruled that out. I started with factory pipe jet specs and have since gone down 2 sizes on the pilot jet but it still hasn't seemed to make much of a differace. It has the stock prop in it right now but it almost feels like it is over proped as crazy as that might sound. My other theroy is that the tank is getting over pressurized. I checked the vent line and nothing is blocking it but it seems like it could be building way too much pressure in the fuel tank and it is over ridding the needle and seats per say. Any and all help would be much appreciated. I am lost for ideas, and i hate to keep gonig down on the jet to compensate for another issue that I am over looking. Thanks again. And I just put a new seat of deal stage reeds in there so the reeds are brand new.

 

[112motorsports]

I am running 155 highes, 77.5pilots with stock 1.5 needle and seat with stock spring. Any others have any differant jeting specs. I am in NC so pretty much sea level. Thanks.

 

[Scorn800]

I have a very similar set up and have good bottom end.
What are you pipe setting? How do you have you cooling set up?
What kind of rpms does it pull up top and what rpms is planing out at?
My boat with 185psi, wet pipe, & timing advance and stock prop & nozzle pulls 7280

 

[112motorsports]

The pipe setting are the following. Bottom closed mid open half way and top around 3/4. When I first got it the mid was closed and the top was open a 1/4 and it ran terrible. Since I let more water in there it runs much better. The cooling is a single line in to the manifold, the out from the front of the head to the head pipe, and the out from the rear of the head PTO side to the stinger Ted to the bypass with a jet works valve in between the stinger. I just noticed that the rear cooling line is a 1/4 off the hear to 3/8 line before the stinger and bypass. Is that the restrictor etc or sould I changed the line to a 3/8 the whole way. I am trurning around 7300 on the top. Thanks. It is planning out around 4000

 

[Scorn800]

How hot is your pipe getting?
I think you may have a water screw clogged, it's common problem on wet pipe sxr's ridden in salt.
Your cooling set up may be wrong also. I run my water line from back of head to bottom of head pipe, line from top of headpipe goes out pisser. Line from front of head goes to tee to stringer then to pisser.
Also I would not run a jetworks valve because the stinger already has a jet in it.
I run the middle closed, top open a turn & half & bottom open 1/4 turn. With these setting the pipe hit good all around. I gained more bottom by proping lower.
Your rpms sound about right.

 

[112motorsports]

So if I am reading you cooling right you are running the single in line to the manifold and not using the drain line at all? Am I correct. That is pretty much the same way I had my supejet set up. Let me know if I am doing this right. I don't understand what the drain is susposed to be for. The in line is to the bottom of the head pipe while the manifold is set up to drain. The the back of the head goes to the pisser and to the stinger, and the front of the head goes to the top of the head pipe. Let me know what you think. Thanks.

 

[Crab]

Bore the nozzle to 80mm, and a cone. I had the return line pop off, and it ran way rich for some reason, make sure the one way check valve is working.

 

[Scorn800]

So if I am reading you cooling right you are running the single in line to the manifold and not using the drain line at all? Am I correct. That is pretty much the same way I had my supejet set up. Let me know if I am doing this right. I don't understand what the drain is susposed to be for. The in line is to the bottom of the head pipe while the manifold is set up to drain. The the back of the head goes to the pisser and to the stinger, and the front of the head goes to the top of the head pipe. Let me know what you think. Thanks.

Yes, I do not use the drain pisser (near the pump) you could though.
The main thing is you run the water from the bottom of the headpipe to the top. By running the front of head to top of headpipe is giving too much water.

Don't bore nozzle or change props till you get decent botton end. Once you get close prop down and go from there.

 

[112motorsports]

So you in line from the pump is going to the manifold? Correct? Thanks.

 

[Scorn800]

So you in line from the pump is going to the manifold? Correct? Thanks.

Yes
I also enlarged the the ends going through the hull to help flow and run 1/2 line water from inside of hull fitting to manifold fitting to help flow.

 

[jMike]

check all your fuel/return/pulse lines for breaks also definetly check those water screws for clogs..

 

[djkorn1]

What Jmike and Scorn said. It is not your prop or nozzle. You are tuned wrong or clogged somewhere.

Are the spitters putting out a good amount of water? That ski should SCREAM on the bottom end.

 

[112motorsports]

oh yeah the water is comming out the pissers like it should. I think I have the water routing wrong and some major fuel issues.

 

[subnsxr]

I have my SXR factory wetpipe tuned on bottom screw 3/8 turn, mid closed and top closed. this is how Wamiltons does it. Cooling lone from head to bottom of head pipe and from top of head pipe to stinger.

 

[kawi--rider]

Have the same setup in my ski..Pipe is set at lower screw 3/4 out, middle screw closed and the top screw out approx 1/4. Need to back your trailer down into the water, warm it up,pull the hood and get your plug wrench ready. Fire it up and pin it wide open for a minute....shut it down and pull the plug quickly to get an idea of what the fuel system is actually doing.

 

[DAG]

not sure if it was said but what's you popoff at? I noticed with my ski it did not follow the N/S mikuni chart. and it was way lower that it was suposted to be which was causing what you stated above. also mabe the salt has made the spring pivot arm start to stick.

 

[djkorn1]

Put some stock carbs on there and use FPipes settings. Those stockers might need a rebuild.

 

[112motorsports]

That is what is baffling me they are brand new stock carbs. When I shut it off running it wide open and check the plugs they look good. I have always heard tune from the bottom up. I am going to re route the water this weekend as well as replace all the fuel lines and check to make sure I don't have a block somewhere. Thanks for all of the help. It just sucks knowing my buddy on his stock Superjet is killing me down low, this isn't suspose to happen.

 

[112motorsports]

Scorn,
You are only running one single line in? No dual cooling. Thanks.