Pressure got the drop on you......
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Pressure got the drop on you......

This is a discussion on Pressure got the drop on you...... within the General forums, part of the Caferacer.net Forums category; ok, clash covers of reggae songs aside, how would I go about dropping the compression ratio of a cb450 without changing pistons? stock compression ratio ...

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  1. #1
    Senior Member Geeto67's Avatar
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    Pressure got the drop on you......

    ok, clash covers of reggae songs aside, how would I go about dropping the compression ratio of a cb450 without changing pistons?

    stock compression ratio is 9:1 and the 500t's comp is 8.5:1, Really I would like to be 8:1. Can I just use the 500T head or do I need the pistons also?

    this is a low budget so I am open to suggestions that don't rape the wallet.
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  2. #2
    buckandaquarter's Avatar
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    For your application, you may also want a copper head gasket. You can tune the compression with a thicker or thinner head gasket (of course there are valve timing changes that go with that.)

  3. #3
    Senior Member robin1731's Avatar
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    You could make a thick copper head gasket. On drag bikes we can get different thickness head gaskets. Can also get different thickness base gaskets. I'm guessing you would have to get a custom one for this though. You might contact Cometic and see if they can make something up for you.
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  5. #4
    Senior Member kenessex's Avatar
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    I suspect the chamber volume on the500 head is larger than the 450 head so would drop the CR. How much? I don't have any idea, but shouldn't be hard to calculate if you had the 2 heads. I agree with Robin, thicker head gasket will help.

    Ken
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  6. #5
    Senior Member Geeto67's Avatar
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    yeah the thicker head gasket is probably not going to be an option seeing as how it is a DOHC where the cam are chain driven and raising the head up will change the cam timing forcing me to degree the cam and slot the cam gears for adjustability - not really what I want to do.

    I was kinda hoping to hear I could take a dremel to a 500t head and take out some material without killing the flame front.
    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
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  7. #6
    Moderator joe c's Avatar
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    thicker base gasket.

    tiny holes in the piston should work too.

    jc



    not a pretty boy honda rider... i\'m fag on a TTR

  8. #7
    buckandaquarter's Avatar
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    Are the cam bearings integral with the head or are they separate?

  9. #8
    Senior Member Diamondj's Avatar
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    Geet - I have a spare 500T head if you want to take a look at going that route.....

    Jim

  10. #9
    Senior Member robin1731's Avatar
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    I guess the cam timing issue wasn't even in my thought's. It is just such a common thing on the bikes I do.
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  11. #10
    Senior Member krapfever's Avatar
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    quote:Originally posted by joe c


    tiny holes in the piston should work too.

    jc
    Or put some crappy ol' rings in there?

    What if you section out a few thou from the middle of the con rods?

    Wait, no. Run it reallly hot for like, 17 hours!

    How about you hone the shit outta yer cylinders?

    I got nuthin.






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