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  1. #1

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    xl1200 piston problem

    Hey guys. i have a friend who has a 2001 xl1200. he blew the motor about two years ago.
    he bought a crate motor and installed it him self.

    he also did the Dplate. he said he took it out and was doing a slow speed run. about 20 minutes in to his ride and it stopped running.
    at that time he said no spark. he put a new ecu in it and it started right up but ran like crap.


    it has sat for the last two years so his limited 2 year motor warranty is gone. he should had done something right away back then.
    anyway he asked me to look at it today. first thing i did was a compression check. 2 and 3 are great. 1 is at 0. it looks like the top of the piston had melted off fully exposing the top ring.

    i am thinking intake leak. maybe crank seal ? that are your thoughts..
    i am going to pull it apart tomorrow and see whats really going on.
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  2. #2
    Myself's Avatar
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    Probably carb issues that were not addressed after the first engine blew. Very common for a DIYer to fix the problem without ever fixing the CAUSE. Some shops are bad about it too.

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  4. #3
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    Agree with @Myself, root cause analysis and fixing is very important when an engine blows up. In my project XL1200 I also had 0 compression on one cylinder which was caused by a creased check valve in the carb. Reason for 0 compression was a big hole in the bottom of the crank case.

  5. #4

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    yep. he has bigger problems. got the head off and i can lift the piston about 1/4 inch up. Crank is shot also. going to get it pulled out and torn down. the carb was my first thought also. i know the pop off can cause a lean cylinder and was probably the reson his first motor took a dump. from what i can see as of now. they have never been apart. will see when they are out. thanks

  6. #5

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    Got the motor out. i think the guy who he got the motor from screwed him. IMO. this was never a crate motor. No chance in hell.. the water jackets were almost closed with what i am saying is salt water calcium build up. i have never seen a fresh water motor this bad. he says it's never been in the ocean. the cylinder walls have a light rust coat on them. maybe from sitting for two years ?. it also has something going on in the 3rd cylinder. there are 2 1/4 inch marks on the cylinder walls. look at 2nd picture. missing bolts all over and the cable body on the oilier was bent down and squished almost closed. he said he had the motor installed buy the seller of the motor.
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  7. #6
    Myself's Avatar
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    Could be an SBT reman. I see sleeved cylinders, AND a 'std' stamp on a piston. They don't come stamped like that from the factory.

  8. #7

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    Is that what that STB sticker is on the head with a serial like number.. maybe this guys is only giving me half truths of his story on this ski. ? when i said friend, he is a friend of a friend. i have been out of working on jet ski's for over 15 years. i have never heard of them until lately. but then again. im old school and only use OEM parts. i honestly believe this motor has more than 20 minutes on it.

  9. #8
    Myself's Avatar
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    Yes, the SBT sticker is a serial number. They can tell you exactly when that engine was bought. They also have piss poor assembly practices. Be prepared to spend a few extra hours cleaning off all the excess sealant and truing up all the gasket surfaces.

  10. #9

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    WOW !. in all my years working on motors, i have never seen a piston melt like this one. i cant believe the crank looks and feels totally untouched. i had to beat the pin out of the piston but the rod looks great. the main bearings look good also.. the head looks almost un touched. but with the heat this went through, im just going to put a new crank in it. how could the water jacket be this plugged up from a 20 minute ride ? the only time i have seen a cylinder this bad was from an ocean ski. the lower end has a bunch of oil in it just like the other two. so this must had been an lean intake leak. are these cylinders Nickel coated or can they be bored.
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  11. #10

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    couple of questions.
    i got the lower end apart.

    1st, is when i removed the crank. the center spacers between the crank bearings were siliconed in place. is this normal on these motors ? i don't see anyone in the youtube videos doing it. I don't have a shop manual. I have never done that before on any motor.

    2nd is the piston pin thrust washers. when i put the two good pistons back in do i put those thrust washers back in. and when i put the new cylinder / piston kit on, do i use the old ones on that rod if it dose not have them or do the new pistons not need them .

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    Last edited by sand_fiend; 06-03-2021 at 11:03 PM.

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