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Old 08-08-2014, 10:59 AM   #1
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Default Meaning of 5+2

I am looking to buy a new engine and some are advertised as 5+2.
Does this mean that it has a total of 7 intake ports or is it 5 intake ports and 2 exhaust ports instead of 1?
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Old 08-08-2014, 11:08 AM   #2
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5 Ports + 2 Bypass Ports

Bypass ports are the ones one the side of the sleeve just below the "normal" ports.


Now, sometimes (very rarely before, never now) manufacturers did that for exhaust, but I havent seen a recent example of it. But the bypass ports is what its referring to. Some manufacturers don't even bother to add that information.
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Old 08-08-2014, 11:29 AM   #3
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Thank You, now that brings up one more question. Do bypass ports function to allow better flow of the fuel from the crankcase to the intake ports or from the crankcase to the cylinder like an intake port?
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Old 08-08-2014, 11:49 AM   #4
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Mixture trapped under the piston when going down can take a shortcut into the transfer chanel.
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Old 08-08-2014, 12:39 PM   #5
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Quote:
Originally Posted by Roelof View Post
Mixture trapped under the piston when going down can take a shortcut into the transfer chanel.
A piston for a bypass port motor will have 2 holes in the piston skirt 90 degrees from the wrist pin holes. That's the other part of letting the fuel short cut into the ports.
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Old 08-08-2014, 11:13 PM   #6
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Quote:
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Mixture trapped under the piston when going down can take a shortcut into the transfer chanel.
^ this.

On top of that this extra port and holes in the piston improves lubrication and life.
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