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Thread: "Hot" Street engine

  1. #1

    "Hot" Street engine

    As some of you know, this has been a two year engine build. Between job changing to get my dream job, to moving 3x, to FedEx losing my crankshaft, cylinder, and a custom piston, to a previous-to-me repair job failing causing the cases to be junk - it's been a bumpy rode, but it's getting there.

    The goal for this engine is a twist on the original Popular Hot Rodding's Engine Master's Challenge, which production based engines were built to a rule set, and scored on how much power they made from 3000-7000rpm as a function of displacement. My intentions are to bump up the RPM range to 3500-7500rpm or so. The idea here isn't so much peak power (though it's cool to talk about), but to build a very fat and stout power curve over this operating band.

    I'll get into the mechanics of everything in other posts, but here is the break down. The exhaust is yet to be built and I'm talking with people about the camshaft, so those are to be seen.

    Shortblock
    Bore: 3.543" (90mm)
    Stroke: 3.307" (stock)
    Rod Length: 5.709"
    Static Compression: 10:1

    Piston: Custom RaceTec forged, with skirt coating, and lateral gas ports
    Rings: Total Seal (standard) 1.1mm , 1.2mm (Napier Style), 2.8mm
    Rod: Carrillo
    Crank: Balanced - welded pin
    Cylinder: through bolting on all 5 studs, stainless O-ring, torque plate honed.
    Cases: Found used low mileage ones, will vapor blast, install new bearings, and perform some oil mods

    Machine work done by Curtis Fiske at Full Circle V-Twin (Flattracker94 on the old site)

    Top end:

    Intake valve: 1.90 (48.25 or +1.25mm over stock), 7mm valve stem, custom valve guide, custom titanium retainer, Ferrea brand
    Exhaust valve: 1.45" (37mm or -2mm from stock), 7mm valve stem, custom valve guide, custom titanium retainer, Ferrea brand
    Intake Port opening: 1.500 (38mm or +2.54mm over stock)
    Intake: Hoos Racing
    Carburetor: Mikuni TM-38, custom velocity stack

    Camshaft:
    To be determined, but currently have a low use Johnson J2 roller

    Exhaust:
    To be determined, but will be a multiple step piece with an anti-reversion chamber, megaphone / reverse cone with a muffler at the end.

  2. #2
    I like it.
    Can't wait to hear more

  3. #3
    Bottom end:

    Shortblock
    Bore: 3.543" (90mm)
    Stroke: 3.307" (stock)
    Rod Length: 5.709"
    Static Compression: 10:1

    Piston: Custom RaceTec forged, with skirt coating, and lateral gas ports
    Rings: Total Seal (standard) 1.1mm , 1.2mm (Napier Style), 2.8mm
    Rod: Carrillo
    Crank: Balanced - welded pin
    Cylinder: through bolting on all 5 studs, stainless O-ring, torque plate honed.
    Cases: Found used low mileage ones, will vapor blast, install new bearings, and perform some oil mods

    Machine work done by Curtis Fiske at Full Circle V-Twin (Flattracker94 on the old site)









    Last edited by Hoffman900; 06-13-2016 at 08:39 PM.

  4. #4
    Intake valve: 1.90 (48.25 or +1.25mm over stock), 7mm valve stem, custom valve guide, custom titanium retainer, Ferrea brand
    Exhaust valve: 1.45" (37mm or -2mm from stock), 7mm valve stem, custom valve guide, custom titanium retainer, Ferrea brand
    Intake Port opening: 1.500 (38mm or +2.54mm over stock)
    Intake: Hoos Racing
    Carburetor: Mikuni TM-38, custom velocity stack

    All port work and flow testing by Nick Smithberg at Smithberg Racing. Nick also spec'ed out the custom valves.
    Edco provided the valve guides for the 7mm valve stem valves and retainers / locks (R/D sourced).

    A lot of work went into this head (different valve shapes tried, different seat profiles, etc), but by all means, it's not a balls to the walls build.






    Last edited by Hoffman900; 09-25-2017 at 07:48 PM.

  5. #5
    More of the head / intake tract:





    Intake Port:


    Left side is with a custom radius plate on the spigot, right side is with the carburetor and velocity stack bolted on. The switch from a 36mm Roundslide to the 38mm Flatslide was worth over 15% more flow.

    Exhaust Port


    * note: .700" lift value is .600" with a pipe off the port

  6. #6
    Interesting stuff. Good to see how it goes once together.

    What material are the valves made from?

    SR
    ...'Any unnecessary items on the bike, that it doesn't really need, shouldn't be there!'. (Café racers creed). SR..

  7. #7
    Senior Member gcrank1's Avatar
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    Are you planning on an engine run video for us? I WANT to hear that puppy run!
    '81 Yamaha SR500 Caff Racer
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  8. #8
    That thing's way hotter than the motor in my race bike. I'd like to see what you'd call "balls to the wall".
    Last edited by Commander_Chaos; 06-16-2016 at 05:45 PM.

  9. #9
    Quote Originally Posted by stewross View Post
    Interesting stuff. Good to see how it goes once together.

    What material are the valves made from?

    SR
    Stew, they're stainless steel.

    Are you planning on an engine run video for us? I WANT to hear that puppy run!
    Oh yeah! It'll be on the dyno.

    That thing's way hotter than the motor in my race bike. I'd like to see what you'd call "balls to the wall".
    Just more compression, more lift, and a bunch more head flow.

  10. #10
    Okay, getting this back on track.

    Pressed out the bearings out of the new to me cases, and just making up a parts list of what I need to buy to get this back together.

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