Porting / polishing an OEM head ?
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Porting / polishing an OEM head ?

This is a discussion on Porting / polishing an OEM head ? within the Grom Performance forums, part of the Honda Grom Garage category; I知 fairly satisfied with my bike at the moment. Having tried a large valve head and having a disaster ( some of you will remember ...

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Thread: Porting / polishing an OEM head ?

  1. #1
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    kc4sox's Avatar
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    Porting / polishing an OEM head ?

    I知 fairly satisfied with my bike at the moment. Having tried a large valve head and having a disaster ( some of you will remember ) I知 wondering if there would be a noticeable improvement in performance if one was to have the OEM head with stock valves ported and polished ? Yeah yeah I know it won稚 breath like a big valve head but having said that would it be worth the time and money to have my head worked ?

    current setup:

    Kitaco 164 light bore up kit
    Kitaco Type 2 cam
    Chimera intake
    PCV with WB2
    Two Brothers Tarmac full exhaust

  2. #2
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    I would venture to guess, yes.

    More air in & out = HP. No denying that fact!
    2018 Grom
    Koso 170 4V/34mm TB/Koso injector/ DIY intake/ aRacer Mini5 + AF1 + DG1
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  3. #3
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    intake and exhaust port porting and also port matching to the exhaust pipe I/D and the intake tube I/D is one of the best improvement to be done for cheap if you know how to use a CNC machine or die grindering tool.

    Another good improvement is to make sure the valves are sitting correctly and flush to the valve seat.

    I just bought some measurement tools for porting both of my spare 181-4v heads using a 5-axies ported head that I got from Japan as a mock up and just coping the measurement internal of the intake port, the exhaust port of the 5 axis was not ported but I will do my own porting and also port match the I/D of the exhaust pipe to the exhaust head.
    hondarider likes this.

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    not worth the effort w/out larger valves

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    Get a kitaco NEO head, neo piston, neo camchain, large throttle body, and that's it. Other moves are irrational. Finbro heads are shit (rough modified stock heads). Porting stock head is always a good idea but it makes near to zero effect in power.
    Only if you have to take off this head for some reason, then do it, lap the valves, make this port job.

  7. #6
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    is HEAD PORTING MASTER LOL
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    lol...... this is a funny read^^^^^ grom fatherz made a real 16hp on the stock piston with the stock valved head. then added the kitaco hc piston and made 17hp.. now the stock head has been modded with oversized valves and stock bore takegawa piston and made 20.2hp. the reason your not seeing big gains is because your porting is for shit
    Vinnie13, zppeacock and hondarider like this.

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