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Intermitent overheating, also mid range bog

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  • Intermitent overheating, also mid range bog

    Took the Polaris sl 650(92 model) out for my first time today. Had a ball when the temp. buzzer would shut up. I have checked the inlet, there is no obstruction. Had a good flow coming off the head rail. Thermostat is gone. I guess I should check the sensor and see what temp sets it off. What temp should it be? I would put a gauge but the kids and wife are better off w/the buzzer.
    Also had the midrange bog. Idles great, runs wfo great, but power falls way off at part throttle. I opened the high speed screws 1/2 turn and it improved, another 1/2 and it got worse so I went back in 1/2.
    Any suggestions?
    BigD

  • #2
    if you have the thermostat housing still hooked up it could be building up sand and momentarily blocking the water flow.

    Rob

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    • #3
      The thermostat housing is hooked up, the 'stat is removed. I went into it and all is clean, it still has the high flow pop-off valve in it, w/ a small hose (1/4") going to the top of the exhaust. Should this be done away with? People keep telling me the buzzer is for a low level in the oil tank. I'm gonna go look for some wires on it, but the alarm should be a steady sound since the tank is completely empty. This alarm would sorta go off and on, and then be off until after 2-5 minutes of wfo. Then it would be a LOUD steady sound. I would go to a idle for a few minutes, and the alarm would go completely off.
      All help is appreciated, BigD

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      • #4
        Ooops, It DOES have a level gauge cork in the oil tank. I put 2 qts. in there and plugged the line. Will be trying it out monday afternoon. Still need some feedback on the midrange bog and if I should remove the thermostat housing and its flow control valve. Thanks, again. BigD

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        • #5
          BigD
          If youre running pre mix do what I did. On my raider the gauge would flash low oil. I just unhooked the guage where it plugs to the wiring harness going to the display gauge and jumpered it. Now the guage thinks the oil tank is full. I would do that rather than having oil in the tank. And then on the other hand at least you have a place to store extra oil if you need it.
          As for the mid range bog. Does it bog down and then take off or is it just a hesitation and them it takes off? if its bogging down and then it takes off then you have too much fuel. at 1/2 to 3/4 throttle position its controlled by the high screws/jet. the low screws/jet only control to about 30 to 35 % of throttle and the rest is mostly controlled by the high screw/jet with the low jet helping a little.
          You said turning it out 1/2 turn made it run better/ I would go from there and turn them in 1/8 th increments. check the plugs for a nice chocolate brown color
          Let me know
          Rob

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          • #6
            Once you took off the thermostat the housing is just another obstruction. Make yourself a t split and run that instead of the housing which had a stepped turn and small hioles to allwo water through. The ideal temp of a ski motor is about 130 degrees give or take a few. also you can check the temp sender by using a pot of boiling water it could be malfunctioning.Unhook it from its place in the ski and bring a small pot of boiling water and drop it in. start the ski on a flush kit and see if it sets it off. i know there is another way to check the sensor, but I cant remember how. If you have one of those Reytek temperature thermometers take it out and then run the ski. point it around at different palces of the ski and you can get temp readings. I use mine when I have skis in the water tankl at my buddy s shop

            Rob

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            • #7
              Raider: The thermostat housing seems to direct water to the ex. man. until pressure builds to a certain point. I'll know tomorrow whether the oil tank alarm was my problem, and then we can go from there.
              As for the carbs, the best way to describe it is: linear throttle response from idle to 1/2, then it's like a light switch from 1/2 to wfo. I can back off maybe 10% from wfo. I know what it's like for a 2-stroke to get on the pipe, but it's not quite like that. These carbs don't have diaphrams, do they? Maybe they could be bad. But I thought that was only carbs w/o fuel pumps that had those. Or is this a characteristic of pwc's in general?

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              • #8
                BigD
                you seem to be running a little lean.if you say it hesitates for a second then goes . Ok do this. go out tomorrow and play with the boat. while youre doing that do the following. hold the throttle at 1/4 1/2 and 3/4 of the way. Each time hold the throttle for about 20 to 40 sec. ive done it up to a minute. when the time is up go full out. see if it hesitates at any of those times. depending on which time it does it ( 1/4 1/2 or 3/4 throttle) youll know where youre running rich or lean as i said before. ( Bryan JUMP IN ANYTIME) HEHE As for the thermostat housing, since there is no thermostat, there is nothing to slow the water down so the water flows continuously.
                there shouldnt be anything to hold the water to the pipe unless you have a small fitting with a jet in the pipe. I know sea doos do not quite sure about polaris. So the pipe is/should be getting a constant flow of water.
                As for the carbs they do have diaphrams. if you look at them youll see a square side with 4 screws on the corners. the square if youlook at it is actually a diamond ( as the carbs sit in the boat). they are on the outside facing the right side of the hull.
                You could probably take them off without removing the carbs. youll need a ratcheting filips head screwdriver with a small head. you could get those at sears. they look like a 1/4 inch ratchet, but have a fillips and a flat head where normally a socket would fit. Undo them and youll see a round rubber piece with a metal center. take them out and hold them up to the light. if you see cracks or pin holes its time to rebuild the carbs. i think Bryan has good prices on them. In my area the kits run about 40 $
                let me know.
                Rob

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                • #9
                  Headin' to the river this am. Will try the above and get back to ya. I did mean to say 1/4 turn, not 1/2 earlier and will fine tune it to 1/16 before it's over. I was just trying to see if I was even in the neighborhood. I had my multimeter out and the oil tank plug opened up, but the probes were not reaching up in there far enough. Then I thought about the waterproof plugs and decided to skip the jumper wire idea. Thanks alot.
                  BigD

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                  • #10
                    Okay, the oil level alarm shut up. Then after 3-6 minutes of wfo I would get a LOUD steady beep. I kept richening the high speed needles a little at at a time, and it stopped alarming. I got it home, took out all the carb. screws after counting the turns in to stop, and found the center carb. was either very sticky or was only out 1/2 turn, while the others were 1 7/8(idle screw) The high speed were pretty close at 3 1/2 turns out. Does this sound about right to anyone? Going out tomorrow and see what I did. Sure had fun today!

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                    • #11
                      BigD, You are way fat on the screws. 3 1/2 out on the highs and even 1 7/8 on the lows is too much for a stock 92 SL650. Are your carbs clean? Take them apart and clean the internal filters. This would explain your bog. Have you felt all the cylinders with your hand when the buzzer goes off? You should be able to place your hand on them. Your pipe also has an orifice that should be cleaned because it might be plugged with debris. The hole is in the tail cone under the water fitting right before the exhaust hose. Take the fitting off and with a paperclip or wire, see if you can clear the hole. Your temp sensor could also be bad.

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                      • #12
                        I'm gonna have to disagree with SL on the part about being able to touch the heads after riding the pwc. Granted, I do not have near the technical experience with Polaris watercraft like he does, but I did own a sl650 all last year and sold it to a close friend this year (so I still ride it often). The domes will be hot to touch and will burn your hand. I know the water circulates through the water jacket and into the heads, but the sheer amount of heat from the cylinder will warm up the heads in 15-20 seconds after shutting the craft off (about the time it takes to dismount and remove the seat) and you will burn your hand.
                        That old polaris puts out white smoke at idle, but runs like a champ and can jump wakes with the best of them. That craft was definitely a great learning experience for me, especially rebuilding and tuning all 3 carbs and replacing a jug and piston assembly all in my garage.

                        Joe

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                        • #13
                          Yes they get hot but not to the point of burning your hand, at least not if everything is ok. BTW, did you guys know that the temp sensor kicks in at 220*F? If you reach that point, you are pretty much guaranteed a seizure when the buzzer or warning light goes off. Optimum temp is in the 125*F range and I don't even know why Polaris put this 220* sensor on the ski. It is actually useless.
                          BigD, you might have a grounding problem of the temp sensor wire, which will in turn activate the buzzer.

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                          • #14
                            Lots of good info. Thanks. Never did get the overheat buzzer in 2 days of riding, probably because it's a little rich. I'm yanking the carbs first chance I get. Looks like they should come loose from the manifolds and come straight up pretty easily. Yeah, it is a fun learning machine and we look forward to getting it running correctly. Thanks again, and I'll let you guys know how everything goes.
                            BigD

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