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  1. #1
    Pistonwash's Avatar
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    How about 5mm stroked, 87mm pistons 66v?

    Hmmmmmmm....when Mr. Lowell rolls out of his shop tonight, maybe he can answer the possiblities. I am sure Greg @ Advent could set-up a proper timing curve.

    Sorry guys..just cabin fever kicking in.


  2. #2
    Hydrotoys's Avatar
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    Where did you come up with the 2.5mm stroke (5mm total)???

  3. #3
    YudLuz2's Avatar
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    LOL, Maybe you should ask the guys at MudBug when you see them run.

  4. #4
    ramnj's Avatar
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    Re: How about 5mm stroked, 87mm pistons 66v?

    Quote Originally Posted by Pistonwash
    Sorry guys..just cabin fever kicking in.
    I'm going CRAZY already Can't wait until March! Luckly I might be riding this Monday, even if I freeze my cojones off!!!

  5. #5
    All hail the Chief! fullboogie's Avatar
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    Mike, it's WAAAAAY too early for cabin fever!

  6. #6
    Moderator RX951's Avatar
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    Is there anyone out there strokin' their motors ?

  7. #7
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    I guess when cabin fever kicks in all you can think about is strokin. Could not resist, How are you doing Mike any new ski projects in the future.

  8. #8
    flyboy's Avatar
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    Jim,

    this is an old post Billy brought back from the abbiss

  9. #9
    YudLuz2's Avatar
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    Talking

    Quote Originally Posted by RX951
    Is there anyone out there strokin' their motors ?
    Stroker's have always been around. But it takes time and money to get
    them right. Using a heavy duty stock lenght rod you can go out to 3mm
    with no problems and it will clear the cases fine. You can take that same rod
    to 4mm stroke but thats about pushing it for that rod lenght. Using a stock Polaris 1200 rod you can gain addition 1 mm over the 1200 Yamaha rod and still use the same piston pin and bearings. You can now take it up to 5mm
    but you will require the cases being cut for the properly clearence when going this large of stroke. Anything over that will require a lot of time and money, and the limit factory will be how much meat is left on the cases. Any other rods (the honda rods are great) will require addition mods for custom pistons or modifed cage bearings or piston pin sizes. This setup would work great on the 1400 and 1500cc motors to get the bore and stroke in line better, you get to the point where you start pushing the piston out the exhaust on the big bores if you don't keep it in line. The proper porting timing and blown down will be require to get the max out of a stroker. I don't have a stroker and I don't really know much about them, but I did stay in a Holiday Inn last week. Ben

  10. #10
    HopatcongGPR's Avatar
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    Quote Originally Posted by yudluz2
    Stroker's have always been around. But it takes time and money to get
    them right. Using a heavy duty stock lenght rod you can go out to 3mm
    with no problems and it will clear the cases fine. You can take that same rod
    to 4mm stroke but thats about pushing it for that rod lenght. Using a stock Polaris 1200 rod you can gain addition 1 mm over the 1200 Yamaha rod and still use the same piston pin and bearings. You can now take it up to 5mm
    but you will require the cases being cut for the properly clearence when going this large of stroke. Anything over that will require a lot of time and money, and the limit factory will be how much meat is left on the cases. Any other rods (the honda rods are great) will require addition mods for custom pistons or modifed cage bearings or piston pin sizes. This setup would work great on the 1400 and 1500cc motors to get the bore and stroke in line better, you get to the point where you start pushing the piston out the exhaust on the big bores if you don't keep it in line. The proper porting timing and blown down will be require to get the max out of a stroker. I don't have a stroker and I don't really know much about them, but I did stay in a Holiday Inn last week. Ben
    well said.

    we could talk about RSR (rod to stroke ratio) but that really has minimal effect on the 66v...even with a 4mm stroke in a single piper turning 7200 rpms....so i wont even bother to discuss here...

    im not going in to much detail here...some things need to remain for the researcher to locate and determin on their own.. ..however, i will say, increased stroke will increase piston velocity and decrease dwell time at TDC with the standard rod....it will also increase/accelerate piston to cylinder wear.

    http://www.e30m3performance.com/tech...io/accel-1.gif

    http://www.e30m3performance.com/tech...atio/index.htm

    increased piston velocity can increase intake velocity which alone (if ported correctly) can lead to increased HP.

    yes, you can go to a 4mm stroke on a 66v...however, you also have to take into account the total displacement in relation to exhaust system volume (point of dimishing returns/peak HP to RPM band)....and DO NOT forget about the pistons exhaust side skirt dimensions. if the skirt is not long enough OR wide enough, you are/will be further limited in stroke (piston @ TDC) AND (more importantly) exhaust port configuration.

    Further.....

    i ran a 14/27 prop on my 86.5mm standard stroke motor last year at 7230-7260 rpm....at 14/28 the blades on a dynafly are near max extension. the impeller and 155mm pump are an area of closely hitting the wall of diminsihing returns, imvho.

    imvho, a 2 mm stroke with a bb is ideal. this allows for some increased piston velocity, decreased dwell time, and increased transfer port dimensions while minimalizing piston to cylinder wall wear.

    the question is how big can you go (displacement) on a single until the point of diminishing returns begins?

    weeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

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