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Heres my problem. I bought a motor off SBT because my front cylinder got cooked out. I bought this ski off someone else and rode it for a couple of hours before it cooked out. It has a factory mod pipe and dual makuni BN 46's. After breakin I noticed that I couldnt get the front cylinder to richen up for the high end adjustment. I thought it needed a rebiuld so I ordered and rebiult both carbs(both have pumps). Still I cant fatten up the top end. Heres what I found in the carbs. Both have 2.3 needles with 80 gram popoff springs and both pressure tested at 17 psi. low jets are 120 and high jets are 105. It says in my BN owners manual that its supposed to have 150 for highs. The rear cylinder looks like its running good but the front is too dry. I got some high jets today;125,135,145,152.5 . Should I just change the front to try to fatten it up? Why would it do this? I cant ride it like this. Its breaking up at high RPM's because of this and I'm afraid to cook out the front cylinder and have to get another motor from you guys.
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what does the plug tip look like? color?
I know Yamaha and Sea Doo like to stagger their jetting, but Im assuming that youre not having a fuel delivery problem at the carbs. Check the fuel line leading to the carbs ( dual fuel lines?) and see if a possinble kink exists. are both the carbs adjsuted the same as far as the high and low needle adjustments? Does one cylinder feel hotter than the other mainly #1 compared to #2. check the carb gaskets or the front crank seal for a leak. use a propane bottole with a hose attached to the nozzle. then startt he ski and turn on the propane and movve the hose around. if the motor revs up you found a leak.
I assume the compression is the same on both cylinders or close
let me or bryan know
Rob -
Check your pulse line to the carb. I had one that had a small hole in it and it done the same thing. After I changed it then the cylinder was running to rich. Just a thought!
Yam
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The front plug is dry and light brown while the back plug is a little darker with an ever so slight hint of moisture. Why would there not be a fuel dilivery problem at the carbs? All fuel lines are clear and new with no kinks(yes dual fuel lines and filters). Both carbs are adjusted the same but even when I open up the front carbs high adjuster it does nothing to fatten it up. The front feels hotter I'm assuming because of lack of lubrication. the compression is the same in both cylinders. Why would it have a leak its a brand new SBT motor? I also found a small hole in the front pulse line and thought that was the problem that smoked the old motor but I put all new lines in when the new SBT motor went in and nothin'. what a wasted summer! Could reeds be a problem?Comment
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check for blow back. put your hand over the carb abd ceank the ski over. if you feel a blowinf sensation you have a cracked or broken reed. Im not saying it is a seal thats bad, but its a possiblity. you could be jaut having a problem with a carb gasket and its making it run lean.
see if its any of those problems if nothing comes of it then you may need to step up the carb jetting on the #1 carb and run staggered getting
RobComment
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