1999 spx tuning

[seadooxp1996]

finally got first ride on water and not impressed compared to 96 xp. i understand that they would be basically same speed. xp is faster top end spx is quicker off line. i still have to fine tune spx but it is a pain to find tuning screws on bottom of carb when seat is off and is in lake. xp has more room to adjust cause it has no accelerator pump hoses. spx seems to reach top speed with throttle at 3/4 to 80 percent squeezed and engine runs smoother at that position on lever. i put throttle to handlebar and i dont notice any difference from 3/4 throttle . y is that? cable is adjusted as manual says . all this money i dumped into it and not impressed at all. aftermarket sponsons damn near throw me off when i try to 180. mains are set at zero and low idle one and half out. accelerator pump is working 100 percent. again anyone looking for x4 hull go with xp and not spx.

 

[mikidymac]

The 99 SPX and 96 XP are the same engine and hull. There shouldn’t be any difference in performance.

What is your top speed and rpm?

 

[seadooxp1996]

55xp 53 spx spx has accelorater pump. xp dont. no idea on rpm cause there is no gauge

 

[mikidymac]

The accelerator pump doesn’t make any difference. A lot of people that have bad pumps just disable them and rejet to 96’ carb specs.
Without a tach it is hard to diagnose your issue.

Could be dirty RAVEs, bad water regulator, dirty carbs, bad impeller etc.

 

[seadooxp1996]

spx is new motor and computer mpem. its an aftermarket mpem . i can program it on mpem. instructions said to get number of block (5) and program mpem for that number. i can also program to rev higher but i put to stock rpm at 7200 . i can rev as high as 10000 but i want it stock.

 

[seadooxp1996]

literally everything has been gone over. raves cleaned. carbs are cleaned. alot of time into this thing. impeller is new, wear ring new. electrical has all been checked and replaced if not working to specs.

 

[mikidymac]

I would get a small inexpensive tach like the TinyTack to verify your top rpm.
The 1995 XP 800 to the 1999 SPX all have the exact same performance with a top speed of 57 mph.
If yours isn’t achieving this you have something wrong.

Also your sponsons are doing exactly what they are intended to. If you don’t care for it just go back to stock. I’m sure you will have no problem selling them.