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  1. #1
    JP44's Avatar
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    SL 1050 Diaphragm Backwards(SOLVED!)

    Hey Guys! Long time no talk. You helped me get my 95 SLT 750 running like a top back in 2011. Ran great until I sold it a few years ago. Thanks again!

    New project...picked up a 97 SL 1050 from a co-worker, $500 including 2 place trailer. Near mint condition, considering its age. Sitting for about 12 years. Spotty maintenance history. Apparently started running poorly at their cabin in Canada, and some people worked on it, and never got it right. Co-worker tried a few things last season when he brought it back here. No luck.

    I just got it today, charged the battery(new last year). Checked compression- MAG 125, CEN 125, PTO 115. Started it on the trailer after changing plugs, and it ran OKAY for the few seconds I ran it. Brought it to the lake and backed it in, leaving it on the trailer. It started hard. Didn't want to idle, ran kind of shaky, would top out at 5900 rpm. Just didn't sound right.

    Pulled the carbs out, pulled reed cages out. Reeds in really nice shape, look new. Tooks some pics of piston wash(or lack thereof). Took carb cover plates off, and the MAG carb had the diaphragm in backwards. What type of effect do you think this would have on the machine?

    The overall condition of this machine is awesome. All little stuff works, except I think the little 1/8 amp fuse is burned out on the fuel sending unit, no fuel level shows on MFD(K447's post). I really want to avoid the stator and electric box upgrade if possible, at least for now until I get the carbs rebuilt and see how she runs. I think this machine will be a blast!

    I guess my only other questions for now are about the two fuel pumps on the carb rack. Replace them? Wait until carb rebuild? Also what do you think about my compression numbers? PTO lower cylinder walls had some surface corrosion. Zigler still doing parts?

    Thanks guys. I've had fun reading through these posts again.

    Jason
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    Last edited by JP44; 09-06-2020 at 11:22 PM.


  2. #2
    Click avatar for tech links/info K447's Avatar
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    Welcome back.

    I would not be ‘waiting’ to do carburetor service/rebuild. The number one way to hurt these motors is to run them with clogged/dirty carbs. Old gasoline is also not doing you any favors.

    You may want to drain and fully clean inside the fuel tank, and clean the sender unit if it is gummed up.

    You can fix also the tiny fuel sender fuse while you have it out, if it is actually bad.

  3. #3
    JP44's Avatar
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    Thanks for the quick reply. Carb rebuild will be the first thing for sure. I am looking for parts right now. Just wondering if that backwards diaphragm is my smoking gun. I will clean and rebuild off of your rebuild link that I just read through. Really handy with the pics. Thanks.

  4. #4
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    The diaphram allows fuel into the carb. With it backwards it wasn’t allowing enough fuel in.
    Check the needle arm height.

    Definitely rebuild the carbs and fuel pumps.
    Not enough piston wash on any cylinder.

    The 1997 1050 engine had some sort of issue with "running compression".
    Polaris used a lower compression head on the center cylinder "# xxx025".
    Mag and PTO used "# xxx050".
    In pictures, looks to me the 025 is on the PTO.
    Last edited by K447; 07-16-2020 at 10:57 AM.


  5. #5
    JP44's Avatar
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    Quote Originally Posted by casey67 View Post
    The diaphram allows fuel into the carb. With it backwards it wasn’t allowing enough fuel in.
    Check the needle arm height.

    Definitely rebuild the carbs and fuel pumps.
    Not enough piston wash on any cylinder.

    The 1997 1050 engine had some sort of issue with "running compression".
    Polaris used a lower compression head on the center cylinder "# xxx025".
    Mag and PTO used "# xxx050".
    In pictures, looks to me the 025 is on the PTO.
    Well I'll be damned! Nice catch! I never would have caught that. I came home from work and checked it, and sure enough the CEN head, 025 was in the PTO spot. Thank you so much for catching that. That is why I love these forums. Unlimited amounts of information, and people willing to help.

    I have the heads back where they belong, and my compression also moved. 125, 110, 125. Once I get the carbs rebuilt here hopefully this weekend, I'll get it back together and let you know how things are progressing.

  6. #6
    savageman69's Avatar
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    those pistons look pretty close to lean

  7. #7
    JP44's Avatar
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    Quote Originally Posted by savageman69 View Post
    those pistons look pretty close to lean
    That's what I'm thinking too. About as bad as I've seen in my limited experience. Hopefully the rebuild helps out. I feel like this has been asked and answered many times, but I'm going to ask again. What is your opinion on how long to wait before checking the piston wash again?

    One other question for everyone. What is your honest opinion about the quality of the $600 ignition upgrade kits? I've read a lot of bad about the quality of the stator, but the box is good? I currently have the 4060170 box installed. After some research it appears this is the old style. After I re-install the carbs, and try it again, I think my next troubleshooting step is the electrical side. I have not tested my stator yet, but I have found a lot of conflicting information about the testing process and values found when ohming out wires. I'm a little hesitant to make my decision based on that test. I will spend the $600 if I have to, but I would really like to get reliable parts. Thanks!!

  8. #8
    How do you tell the difference between the lower compression head and the normal one? is the number stamped on it somewhere?

  9. #9
    JP44's Avatar
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    Quote Originally Posted by acanofdrpepper View Post
    How do you tell the difference between the lower compression head and the normal one? is the number stamped on it somewhere?
    Yes, the numbers are stamped on the top of the heads, you can see them if you take the red head covers off. If you can't read the numbers, which I don't think would happen, you can remove the head and turn it upside down, like in my picture, you can clearly see the "dome" on the bottom of the picture is bigger on the lower compression head. When I say "clearly", that is only because Casey67 pointed it out. I never would have noticed on my own.
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