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  1. #1
    srjrinc's Avatar
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    Finally bought a broken rxp !!!

    So I finally got my hands on a broken 05 RXP with 49 hours! ( I'm completely new to 4-Tecs by the way)
    I've been looking for a project like this to learn the 4 Stroke ways.....(couple 2-stroke re-builds under my belt)
    This RXP has 0 compression on the #1 piston (pto) and about 130 on #2 &# 3 .....Where do I start????
    What are the most common causes of this issue ? Valves will get replaced since I will be already at the top end.
    Just trying to get a head start with some advice from other members.....Thanks Guys!


  2. #2
    leejax01's Avatar
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    Well first. Is there damage to the cases or just a dropped valve with piston/ head damage? Need to yank the engine and see what's the damage and caused it. The 4 stroke isn't as forgiving as 2 strokes and would recommend having someone local if possible to double check things or post plenty of pics and get the help that way.

  3. #3
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    Sounds like it lost a valve....thats common for 04/05 heads...

  4. #4
    srjrinc's Avatar
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    Quote Originally Posted by leejax01 View Post
    Well first. Is there damage to the cases or just a dropped valve with piston/ head damage? Need to yank the engine and see what's the damage and caused it. The 4 stroke isn't as forgiving as 2 strokes and would recommend having someone local if possible to double check things or post plenty of pics and get the help that way.
    Thanks, just trying to get some direction, I will pull the engine and start tearing into it. I will post pics of what ever I find. Thanks for your help!

  5. #5
    srjrinc's Avatar
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    Quote Originally Posted by Danny View Post
    Sounds like it lost a valve....thats common for 04/05 heads...
    'll look for that......What are the stock compression #'s for an RXP ..... 170 ???

  6. #6
    boost junkie skidoochris's Avatar
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    no, if the motor is only 8.4:1 then 8.4 x 14.7 =123.5 psi and 8.5 x 14.7 = 125 and 9x 14.7 = 132.3
    if you dropped a valve you might as well look for an other motor, bet ya its junk

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  8. #7
    srjrinc's Avatar
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    Quote Originally Posted by skidoochris View Post
    no, if the motor is only 8.4:1 then 8.4 x 14.7 =123.5 psi and 8.5 x 14.7 = 125 and 9x 14.7 = 132.3
    if you dropped a valve you might as well look for an other motor, bet ya its junk
    Dang!!! now I have to loo into that compression ratio!..... I going to pull it apart and see what's going on first and see if any thing stands out first! THANKS!!!!

  9. #8
    boost junkie skidoochris's Avatar
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    now those numbers are not corrected for valve timings or oversize pistons

  10. #9
    Dropped exhaust valve?.... 72 prefix part # on the valve stem is BAD NEWS.. A Busted Intercooler core? (freeze)..... A Bent Rod that squared the piston bore..? (Engine that ingested water)? are all things to check & most pertain to the #1 cylinder failures..... Just depends on how much it got ran after the orginal damage will determine the cost to fix it.....

  11. #10
    srjrinc's Avatar
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    Great, thanks!!!! I'm just going to start to pull it apart and see what I have..... A lot of info, but its leading me in the right direction!!!!, you suggest to pull the motor completely out or just the head?

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