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  1. #1
    Senior Member Tiny-Wheel-200's Avatar
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    no compression.

    installed an engine with a kickstart I bought off ebay years back and it seems to have low or no compression. what am I looking at in terms of what's wrong and what needs to be done. the engine has sat unused for at least five years indoors

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    Member jonnyquest's Avatar
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    Quote Originally Posted by Tiny-Wheel-200 View Post
    installed an engine with a kickstart I bought off ebay years back and it seems to have low or no compression. what am I looking at in terms of what's wrong and what needs to be done. the engine has sat unused for at least five years indoors

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    I think you have a valve that's stuck open.

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  3. #3
    Senior Member bartruff's Avatar
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    No muy Bueno....if it needs a complete rebuild, that used to cost about $800.....hoping for something minor....

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  5. #4
    Senior Member grewen's Avatar
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    yup, i would check that the valves are moving first. pull the valve covers is the easiest place to start
    Greg

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  6. #5
    Senior Member Tiny-Wheel-200's Avatar
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    so if the valves arent moving how would I proceed? is there some way to unstuck them or do I need to start eeplacing things? this is new territory for me.

    I should note this is à pre 2000 engine and I have a parts engine from a 2007 bike that I can use as à donor
    Quote Originally Posted by grewen View Post
    yup, i would check that the valves are moving first. pull the valve covers is the easiest place to start
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  7. #6
    Super Moderator Purple's Avatar
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    The usual cause of a stuck valve (in your case) is corrosion of the valve stem. A simple spray of penetrating oil may well cure this, from the top. If you can get the valve to release like this, follow up with something a bit heavier, like 3 in 1 — do not attempt to start the engine, just keep applying oil until you can crank it by hand (or foot) to prove that the valve action is free

    All you’re trying to do is dislodge the rust on the stem. At this point, assuming some success, you can go on to starting the engine — the moment it fires up, shut it down — more oil onto the stem — rinse and repeat

    The downside to trying this without taking it apart, is that once you have the stem moving, it might let too much oil past. We call this “overhead sump syndrome” — but you might get lucky. A simple compression test will reveal all you need to know

    As long as you don’t run the engine for longer than a few seconds, it can’t hurt to find out …..
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  8. #7
    Senior Member elime's Avatar
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    Quote Originally Posted by Tiny-Wheel-200 View Post
    so if the valves arent moving how would I proceed? is there some way to unstuck them or do I need to start eeplacing things? this is new territory for me.

    I should note this is à pre 2000 engine and I have a parts engine from a 2007 bike that I can use as à donor

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    If you have a complete 2007 head just swap it over.
    Long live the internal combustion engine!

  9. #8
    Senior Member Tiny-Wheel-200's Avatar
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    OK so bumping this up. The valves are moving fine so it seems like it might just need rings or a new piston? How many hours would you estimate to do this and do i need to remove the engine to do this?

  10. #9
    Member jonnyquest's Avatar
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    A valve still may not seat completely or even the valve seat could be bad too. A friend of mine bought a Honda XR a few yrs back with no compression. The valves moved, but nothing. We found a bent valve from someone over revving it. Replaced the valve and everything was A-ok.

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  11. #10
    Senior Member arbolmano's Avatar
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    Before getting too excited, put some ATF down the spark plug hole, like two tablespoons. Crank over and let set a little. You can take off the little adjustment covers and check valves. I’d adjust whilst there. See how much compression comes up. Maybe sufficient to start. Rings can stick from sitting too much. Might fire up an clear up. Unlikely however. I find it’s easier for major work to pull the unit. But I’m old an can’t see that good plus my back won’t let bend over too much. At least put the bike up high like on a drum or low table. Highly advise download manual, directions really help.
    Go man go
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