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  1. #1
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Rodneyae, got a question about Swifts cylinders

    Did you have them bored or were they already .20 over when you got them?
    Reason I ask, is from what I've read and understand, is that when they are bored the height of the ports are lowered (because of the angle of the ports). And this changes the port timing to have more lowend pwr and will limit the high end rpm.
    When they were bored, was the port hights re-adjusted to compensate for the new bore?
    BTW..Do you need to pull the General apart this winter to do any work?


  2. #2
    Water Bum Rodneyae's Avatar
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    Cyclinders were already bored .20 over. I imagine the port job was done at the same time, as Wiseco dose't offer a std. size piston and the clearance was set up for a forged pistons.

    The General is running fine, and I have already started on another winter ski project. I am guessing you are wanting something?

  3. #3
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Well if you were going to pull things apart, I was going to ask to borrow a cyl. to get some port specs from it. Its all good. I found a couple of oversized jugs, and looking for 1 more, just in case I screw something up or keep them as spares. Or use them on the 650, as I have all the other needed parts from the 780.
    Thanks anyways.

    BTW...what do you have burning in the fire now?

  4. #4
    Water Bum Rodneyae's Avatar
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    Here is a hint, plus lots more stuff, for the unnamed ski.

    Click image for larger version. 

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    If I get some additional time I might be able to do that for you.

  5. #5
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    The hint looks cool! Is it an intercooler, or a mean looking intake?

  6. #6
    cheatin' piston popper addicted's Avatar
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    Star, not sure if you came across this thread, but there are alot of good pics of the jugs in it

    http://www.greenhulk.net/forums/show...t=addicted%27s

  7. #7
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    I've been through the threads, but its really hard for me to measure port demensions from pictures.
    I have specs from factory 750's and 780's, and Keddano may send me a template from his ported 750. I will compare the two to see how the ports changed to accommodate the PSI pipes. Having the ported 780 jug would also help me gain a huge amount of knowledge in my endeavor of learning the Art of Porting. I'm just trying to gain more knowledge in my hobby. I'd even be willing to pay to go to school for this info.

    BTW..I do love looking at jugs, I just need a hands on approach.
    Last edited by starflight; 12-07-2007 at 11:37 PM.

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Star, what do you need specifically measured? I've got the PSI 780 cyls that are way tricked out. They are gas valved though, so that will vary exhaust port heights.

  9. #9
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Could you edit the 780 in this chart w/ your ported 780's demensions, or create a template of it's ports layout?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Nice chart Star!!!! Here's what I got, keeping in mind it's with a dial caliper, not anything high tech...
    Exh port height A 41mm (exh valve closed) 34.5mm (exh valve full open)
    Exh port width B 50.5mm
    Exh boost port height C 37mm
    Height/width D/E 12.5 x 14.5mm
    Main transfer height F 50.5mm
    Main transfer width G 27mm
    Rear transfer height H 49.5mm
    Rear transfer width I 25mm
    Boost port height J 50mm
    Boost port width K 21mm

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