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Discussion Starter · #1 ·
i have a t4 its been ported and i dont know the orignal port lay out.they did a really shit job so i had it reported (just cleaned up) and its way better but id like to know what its been ported for.:D
 

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Did your shop give you the specs on the port job?

Porting really has little to do with how it looks... it's more about changing port timing to better match your desired riding style.

To check port timing

Mock up the cylinder w/ piston on the engine - make sure you use a base gasket and torque the cylinder down when checking your port timing - as base gasket thickness will affect the port timing.

Use a degree wheel to measure actual port timing - Opening and closing of the exhaust and scavenge ports.

Stock 1987 T4:

Exhaust: Open 88.25 BBDC
Close 88.25 ABDC
Duration 176.5

Scavenge: Open 59.5 BBDC
Close 59.5 ABDC
Duration 119

There are quite a few other things involved also - like shape and size of the exhaust port in relationship to the cylinder bore size - setting up squish and proper dome shape in the head for the intended riding style and fuel used.

Hope this helps
 

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I have some pics of a ported cylinder but nothing stock.... Alot of the high end companies dont want to show people what they do for port work for usually 2 reasons. One they dont want to give away any secrets or Two they dont want people to see how little work they do for the money IMO...
This is before I finnished cleaning things up but you get the idea at least




 

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The port work dont look too bad but they didnt do the polish on it to really smooth it down. Some places dont do polish work anymore because some argue that you get better #'s with disturbed air flow vs. smooth air flow.
 

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Discussion Starter · #5 ·
thanks guys.. but after i figure the port timeing how do i tell whats its for?
 

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The port work dont look too bad but they didnt do the polish on it to really smooth it down. Some places dont do polish work anymore because some argue that you get better #'s with disturbed air flow vs. smooth air flow.
Like I said I havent finnished this yet, and all the port work you see I did myself from a stock cylinder. There are several hours of porting time into it so far. I dont polish anything in the intake just sand blast to bring out any tooling marks. Then smooth everything out and sand blast one more time. The exhaust gets coated instead of any polishing. It works much better and carbon doesnt build up on it plus it dissapates heat better. Once this is back from the welder and it gets bored I will finnish the port work. After that its off to the plating company for nikisil.
 
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