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Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft

Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76

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  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
  • Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft MAP9217/76
Triumph 650-750cc Twin 76-Degree Offset, Stroker Billet Crankshaft
We only have 3 left in stock
We only have 3 left in stock
$1,950.00
Build the smoothest Triumph twin possible with MAP's 76-degree crankshaft!
$1,950.00

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Description

Details

Would you like to build the smoothest Triumph twin possible? Then, you'll need to start with the 76-degree M.A.P. Crankshaft.

Triumph twins have always been known for creating a lot of vibration. That's because both pistons rise and fall at the same time on the standard 360-degree crankshaft. The 180-degree crank is smoother, but it suffers from rotational vibration due to increased rocking couple, which is best described as plane imbalances on the Y or Z axis of the crank (basically twisting at the ends). Cranks use counter weights to offset these vibrations, but these weights have limits to what they can do. The 76-degree crankshaft allows one piston to be at top dead center while the other piston is just reaching it's maximum velocity. This offers the smoothest possible motion in the crank and eliminates much of the vibration in the Triumph twin.

Fits:

  • All Triumph 650-750cc Twins built after June 1971 (GE27209) though 1983 with metric timing side main bearing. Can be adapted to earlier 650cc twins (see below)

Specifications:

  • 89mm stroke
  • 1-3/4" journal (use with Norton Rod Bearings)
  • Approximately 22 pounds

Features:

  • 4340 American Billet Material - 4340 steel
  • Rated 140,000-145,000 psi 
  • The strongest alloy used for cranks
  • Triple heat treated
  • "Ion Nitrite" treatment for longest life (similar to British Tuftriding)
  • Ionized nitrogen is vacuum deposited onto the crank surface in an oven, penetrating .010 to .012 inch into the metal surface and changing the microstructure of the steel, surface hardness is doubled from 30 to 60 on the Rockwell scale, while fatigue life is increased by 25 percent.
  • Shot peened to reduce internal stresses
  • Generous Crank "Fillets" for strength and rigidity
  • Out-bounded Counterweight to lessen crank flex

Note:

  • Requires stroker rods
  • Use of some rods and piston combinations may incur extra costs due to the cost of additional Mallory Metal
  • The 76-degree crankshaft can be used on pre-1971 models, but it requires that the crank be turned to fit imperial unit (inch) bearings. Please see product questions for a more in-depth explanation.
  • Cranks are balanced at 50-percent.  If you forward precise bob weight, we can balance it for you. This must be supplied at the time of the order. We do not do any calculations. 
  • This must be used in conjunction with a 76 degree electronic ignition, and 76 degree camshafts.

About crankshaft bob weight:

  • Bob weight is the amount of weight added to each journal before it is spun also known as dynamically balanced. It is calculated in the following manner:

Bob weight = (complete piston assembly +small end weight) X (balance factor) + (big-end rod weight + bearing shells) 

Additional Information

SKU MAP9217/76
Material 4340-Forged
Manufacture MAP Cycle
Country of Manufacture United States
Additional Information

Additional Information

SKU MAP9217/76
Material 4340-Forged
Manufacture MAP Cycle
Country of Manufacture United States
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What type ignition is used with this crank
1
I am considering a set of Thunder engineering pre- unit cases and I have a Morgo 750 kit. What rod length rod would I use with this offset crank and the Morgo kit ? If I go with the thunder cases I can get them machined for supper blend bearings?
1
Can this crank be used on a earlier T120 engine?
-1
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