97 GTX Performance

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
#1
I just went through the carbs on the GTX. Newly rebuilt with Mikuni parts. I am tuning them. Much testing and checking last week. On the water today, I couldn't get the ski to come hard enough to open the rave valves. My wife noticed the ski running differently right away... I gotta give her credit. :) It feels like the ski is not getting enough fuel. I'd play with the throttle, tweak it, nail it and sometimes the raves would kick in and then HOLD ON BABY !! LOL Previously I had a stumble at transition to about 4500RPM and I cleaned the carbs last week. I found some issues with pop-off and such. . Above half throttle I can do whatever I want and the speed does not increase, then when the raves kick in... hang on. I reset the raves where they were (about 3/16" past flush with the top of the cap. I made them flush last week and went back to the previous setting.

Question... is there any chance my carb settings are the problem. I'm at 1 turn out on the low speed, 0 on the high speed. On both GTX's there feels like there is more power to be had at high RPM. The 97 GTX is running close to 7K when the valves open. The 96 is getting about 6700. The carbs on both skis are set exactly the same.

Help a brotha out !! :D:D
 


tobytd

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Norris Lake, TN
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98 GTX
97 GTX
96 Polaris SLT 700 (sold)
#2
You know about early style rave housings. ' Actuation' ports cut open to valve stem Updated ones closed
 

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
#3
I know they are different. The ski had no problems the first weekend out with the top end. Broke it in slowly and it was great up high. I pulled the carbs to figure out why the transition was so coarse. So I cleaned everything again, I got a bit of dirt out of there and made absolutely sure those 3 holes in the barrel were clear. Funny, I soaked each carb for hours in carb cleaner and did my carb cleaner spray and air blowing and checking. C'est La Vie. :) Put the ski in the water today and it had issues. May not be a rave valve issue, may be a carb issue. When they opened hold on to your drawers. LOL

I'm thinking carb adjustment but asking for advice. I absolutely hate the fuel circuit on these machines so I am trying to understand it better.
 

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
#4
I'm gonna get on this job tomorrow. Pull the rave caps and have a look. I really believe it is a carb adjustment or carb problem.

I also noticed on my 96 GTX when steady at 5000 RPM it drops off to about 4700.... then back up to 5000. Seems like it is lean. Would it be a good idea to open the high speed needle a bit to give it more fuel?? This may be the same issue with the 97 GTX. Thoughts ??? Hook me up cuz I'm going to the canal with tools and testing... LOL
 

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
#5
Raves look good and a moving freely as I expected. I have less than 10 hours on the rebuild. Here is my plan.... I believe I don't have enough Pop-Off Pressure and the ski gets too much fuel at low speed. Pop off is around 23psi. I am looking for the pop off suggested range. Both these skis do not have good transition phases. I need to find out where I can buy an assortment of springs. I'd like to get the pop-off around 30 or higher and see what happens.

Then of course....they both feel like they are starving for fuel at High RPM (WFO) I have the High Speed adjuster full closed on both. I want to get the pop-off set higher then I will take the ski out with some plugs and do some tuning. I've never had this much trouble getting engines tuned... Yikes !!
 

mikidymac

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2001 XP
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1996 HX
1991 Superjet
2001 Superjet
#6
First off don't change springs or pop off. You have something else going on.
Both of your 1997 & 1996 GTX's use the same carb specs....
1.5 Neelde and Seat
80 gm Black springs
23-43 pop off, Anything in this range is fine so don't get too carried away with trying to raise it.
142.5 Main Jet
70 Pilot Jet
Low Screw = 1 turn
High screw (Mag = 0, PTO = 1/2)

Any stock seadoo will run perfect on the stock settings so if you have problems then something is wrong.
 

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
#7
Agreed.... but not two skis doing close to the same thing. Unless I built the carbs wrong 4 times. LOL I have an open mind. :) Thanks for the tip on the PTO Carb. Mine are all zero on the high speed. I'm going to the canal this week with tools in hand and extra plugs.

A calm sea never made and skilled sailor. :D :D
 

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