Guys I really need some help!! I purchase a 98 XPL with a Blown Motor and decided to spend $2,000 for a new SBT motor and installation at a non sea-doo dealership. I decided to rejet the carbs and add airfilters and have them jetted according to Aftermarket specs. My XP will only tops out at 56mphs and max rpms is 6400. I check the compression and it is at 125psi while my other stock 951 motor is showing 135 psi and the SBT comformed that their 951 rebuilts have a slight lower compression then the oem ones. So why is my RPMS so low?? Timeing ?? how can I check it? Jett Settings ??Has anyone else had this problem with a SBT Motor and if so what Did I miss.
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Low RPMS on New seadoo 951 SBT Motor
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Re: Low RPMS on New seadoo 951 SBT Motor
check the raves to make sure there working ok . what jetting /popoff settings are you using ? the lower PSI is fine i setup most of my motors with lower compression but tune for more topend .PRIDE IN SERVICE<br /> <img src="http://www.sbtontheweb.com/images/forposts/4609/1.jpg" alt=" - " />
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Re: Low RPMS on New seadoo 951 SBT Motor
My Jet Specs are Hi Speed 1/2 turn out and low speed 1 3/4 turn out. How do I check the rave valve? I head to hook up a hose to an exhaust and rev up the rpms to see if it hits the rev limiter around 7500 rmps to see if your timing is ok. Does that sound like a good Idea?
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Re: Low RPMS on New seadoo 951 SBT Motor
take off your black caps . push down on the raves and put your finger over the air nipple , then let go of the rave it should not come back up , if so then the raves are leaking some . easy fix . also take the ski to the water and try running with the rave caps off . your bottom end should be slower but topend should be back up if the raves are not working right .
also what jet sizes are you running ? and what kind of FA ?PRIDE IN SERVICE<br /> <img src="http://www.sbtontheweb.com/images/forposts/4609/1.jpg" alt=" - " />
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Re: Low RPMS on New seadoo 951 SBT Motor
Carolinadocks, I experienced a problem with missing RPM’s after installing an SBT engine. My engine would only reach 6600 RPM’s. After posting here, and getting the following info:
· Check carburetor jetting, and needle settings.
· Check engine timing.
· Check water box valve.
· Check RAVE valves, hoses, and solenoid.
· Check engine alignment.
I tried all of these but I was still missing 300 RPM’s. So after talking with a reputable shop they also advised me that when an engine is assembled the cylinder port timing should be set to factory specs. If the piston cylinder is lower than factory spec you can loose RPM. If you raise the cylinder higher than factory spec you can gain RPM. My SBT motor came with a base gasket that was so thick it is not even listed in the Sea Doo manual, and my cylinder port timing was still low. After razing the cylinder to factory specs I gained my lost RPM’s back (but also lost some compression).
I’m sure that SBT receives some really bad cores, and that they have to mill the heads, cylinder, and case sometimes to square things up. But if the cylinders are not set to factory specs you could see an RPM increase or decrease. Good luck hunting down your problem.
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Re: Low RPMS on New seadoo 951 SBT Motor
Revving an engine out of the water on a garden hose will tell you nothing about ignition timing, or much of anything else for that matter. Your oem rev limit is 7150 rpm.... It still has nothing to do with timing. Your motor should run around 6800-7000 rpm while riding at wot.
Typically, if the engine won't get the full rpm, you either have a rave valve issue or your water regulator on you muffler is leaking too much water into the hose that goes to the pipe at higher rpm. Another possibility is that you got the TPS out of adjustment when you re-installed the throttle cable.Bill O'Neal <br>
WCM
<a href="http://www.watercraftmagic.com"
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Re: Low RPMS on New seadoo 951 SBT Motor
I will check the raves this weekend and did a plug test 2 weeks ago. I put in new plugs and ran at WOT for about 5 minutes and they looked okay Brownish. Is that enough time? I have no idea of the size of the aftermarket jets I used flyracing for my air filters
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Re: Low RPMS on New seadoo 951 SBT Motor
the seat is easy to get off . undo the shock and 2 bolts under the hood, you should pull your jets and get the numbers . 1/2 a turn on the highs is a lotPRIDE IN SERVICE<br /> <img src="http://www.sbtontheweb.com/images/forposts/4609/1.jpg" alt=" - " />
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Re: Low RPMS on New seadoo 951 SBT Motor
I can tell you right now that if you installed larger main jets your high speed needles should be closed. If they are 1/2 turn out, that will lower the rpm by alot.Bill O'Neal, owner of Watercraft Magic in Glendora California, www.watercraftmagic.com
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Re: Low RPMS on New seadoo 951 SBT Motor
Hell Yes.Bill O'Neal, owner of Watercraft Magic in Glendora California, www.watercraftmagic.com
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