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  1. #1

    Finally rebuilt (300 conversion) and.... Knocking? Need Help Won't Start

    Hey guys ever since my supercharger went in my 255 I rebuilt it and had the PTO housing machined for the 300 hp super charger. After putting it back together it won't start... All I hear is a loud clanking noise that sounds horrible. I am use to hearing it rough as it starts normally but nothing like this and it won't start.

    While I had the head off I machined the head as it was a little bit uneven granted this is at the max limit or even slightly past the max limit for machining the head. I also swapped out the Cam Shaft for a performance cam.

    Would anyone be able to help me diagnose what to do now. Frankenstein is fully built but has 1 gremlin left. I am curious if timing is off by 1 notch will it not start and will I get this knocking noise? Would the head being machined that much cause this? Shit cam?

    Please help been dieing to ride this thing been a 5 week rebuild as I was waiting for parts and what not.

    Video: https://www.youtube.com/shorts/6QD7Qi_Pbjs
    Last edited by taserz; 08-13-2022 at 07:22 PM.

  2. #2
    Myself's Avatar
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    Ouch! You sure that's not valves hitting the pistons.....timed off the front cylinder instead of the rear?


  3. #3
    Quote Originally Posted by Myself View Post
    Ouch! You sure that's not valves hitting the pistons.....timed off the front cylinder instead of the rear?
    I was fairly confident I had the teeth lined up straight and I had Cyl 3 locked TDC.

    Cyl 3 being the one closest to the handle bars right... now I am questioning it all

    Also if it's valves hitting piston would damage be done if it never actually ran just tried to... (for some time)

  4. #4
    tiderider's Avatar
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    I would pull the engine and try, try again..

  5. #5
    What should I be trying again though

    If it's just timing on the gear I can find TDC again and lock crank again without pulling the head. Then I assume I would take rocker arms off get camshaft locked put timing gear on again and double check it's straight then redo rocker arms.

    But if your suggesting I go further what should I be doing?

  6. #6
    Myself's Avatar
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    Yes, #3 is forward. Bring it around to TDC again and look at the cam sprocket, do the horizontal lines match up with the head casting surface?

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  8. #7
    Thanks guys I think my cam shaft wasn't TDC when I locked the wheel on or something during the rocker install like I didn't have the pin all the way down...

    So... It now sounds great as it attempts to run...

    It doesn't start. I smell gas coming out the exhaust after trying for a while. Fuel pressure rail shows close to 80 so I know it's got fuel.

    I do have a bad TOPS switch I ordered a new one. Would that be causing it not to start? I can't find it in the manual if it is unplugged or not working if it will start.

    So close I can taste the victory but any help is appreciated

  9. #8
    SplishSplash's Avatar
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    Do a compression check, make sure it's OK.
    Do you have spark?

    Maybe it's flooded , hold wot and crank for 10 seconds . Then try a normal start and see what happens.

  10. #9
    tiderider's Avatar
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    See what I posted earlier?? Oh sh..

  11. #10
    Quote Originally Posted by SplishSplash View Post
    Do a compression check, make sure it's OK.
    Do you have spark?

    Maybe it's flooded , hold wot and crank for 10 seconds . Then try a normal start and see what happens.
    I have compression about 110 psi on each cylinder when cranking with the gauge on it.

    I pulled a spark plug and ran it outside the engine and I saw the spark plugs fire off. I also let it sit and tried what you said. Still no luck. Could it be too much gas it is new vt1100 injectors and a new tune but idk... this is confusing now

    Quote Originally Posted by tiderider View Post
    See what I posted earlier?? Oh sh..
    You didn't say much. You said pull the motor and try again

    Why would I pull the motor I didn't have to pull the motor when I did this work? Also try what specifically again? I didn't make any big changes. I replaced the supercharger for a different one which is straight forward. PTO housing is just unbolt and re-bolt (Had to get it machined to fit new charger) nothing too crazy there either. I now know the engine was not timed so I fixed that. It sounds great as it tries to start but I am stumped what would pulling the motor do if I don't know what to check.

    Don't get me wrong if I have to pull everything out to check the motor I will but that's a lot of time to do that so rather do that last. Also I don't have the ability to pull it from the ski so I have to work on it in the ski. (PTO was a bitch to do but found the trick is to loosen starboard side engine mount lift motor and jamed a block of wood under it to make those bottom bolts doable

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