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Finbro superhead quality = meh

This is a discussion on Finbro superhead quality = meh within the Grom Talk forums, part of the Honda Grom Forums category; Whelp, as many know i have been running the stock head with stock valves on my 164cc kitaco bbk. This is the single biggest bottleneck ...

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    Finbro superhead quality = meh

    Whelp, as many know i have been running the stock head with stock valves on my 164cc kitaco bbk. This is the single biggest bottleneck i currently have on my setup (see build in signature).

    I realized i needed a bigger valved, better flowing head, and unfortunately the only game in town for something of the sort is Finbro. 250 bucks gets you a head with 27/23mm valves (stock is 25.5/20.95mm). The size i really wanted (28/24mm) was going to be 350 shipped.... no thanks.

    Franco from finbro got the head shipped to me very quick in nice proper packaging with a new exhaust gasket, sweet!


    My problem is, for 250 bucks, I expected MUCH better QA on finbro's part, especially considering you can buy a full OEM head and valves for ~70 bucks. The porting looks decent, but when i started looking at valve seating and the combustion chamber its when things started to fall apart. The valves seated so poorly you could see light through where they should of seated into the ports if you shined a flashlight in the combustion chamber. This. is. not. acceptable. It was at this point i realized, ok at a minimum valves were coming out to get lapped into their seats. So i pulled the valves out to find this.

    Finbro superhead quality = meh-valve1.jpgFinbro superhead quality = meh-valve2.jpg

    That black ring is the tiny contact patch of the valve, super rough and almost pitted.... lots of lapping was needed to get a proper valve to seat seal.


    Once I had the valves out I started looking at the combustion chamber itself and was disgusted at the INSANELY sharp edges left EVERYWHERE especially around the exhaust valve.... sharp edges lead to detonation (pinging) which I have in my current setup under certain conditions when the motor is fully heat soaked. So this shit had to go.
    Before:

    Finbro superhead quality = meh-cyl1.jpg


    A little sharpie and some dremel stones to start knocking down the hard edges. I unshrouded the intake and exahaust valves as much as i could without taking too much material and got rid of the nasty points between the valves in the middle of the chamber. I am currently waiting on my 60mm bore headgaskets from kitaco. Once i get those the last edge to get smoothed out will be the outer
    Finbro superhead quality = meh-cyl2.jpgFinbro superhead quality = meh-cyl3.jpg

    Once i do the final outer lip i will do a good lapping of the cylinder to head surface and things should be much better (ill update this as i go). Now i know that removing material out of the combustion chamber reduces compression, but im not too worried. The amount of material removed was not much and to be honest i was going to go with 2 base gaskets to reduce compression anyways to make for a longer lasting motor. All in all win win.


    All that stated. If you are looking for a bolt on properly done head. The finbro head IS NOT the answer, it will require work to make it how it should of come from finbro.

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    Strokd_GE's Avatar
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    Lolol great lapping on those valves

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    Quote Originally Posted by Strokd_GE View Post
    Lolol great lapping on those valves

    Lol right. It took quite some time to make a proper seal with the seats. After im done with polishing the hard edges im going to wash the whole cylinder out then do one final lapping of the valves and call it good.

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    My current commute is 4mi each way so having a strung out 125 isn’t nearly as fun as it was when I had a 20mi commute and because of that I’ve been entertaining the idea of a Kitaco 164 with a bigvalve head but when I see such stunning quality control I feel like I might just port a stock head be happy knowing there’s quality pieces in there
    Last edited by Strokd_GE; 11-06-2017 at 07:22 PM.

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    I thought the factory is supposed to do a leak test to make sure the valve is seated tight.

    Did you contact Finbro about this?

    Sent from my LEX727 using Tapatalk

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    Quote Originally Posted by Cheburashka View Post
    I thought the factory is supposed to do a leak test to make sure the valve is seated tight.

    Did you contact Finbro about this?

    Sent from my LEX727 using Tapatalk

    Nope. But I am going to link him to this page. I wouldnt be spending 250 bucks on this head ever again. I should of just taken the stock head and ported / polished it and called it good.

    I will be taking the stock head off and doing measurements of ID of the ports at the valve seats.... i have a rather suspicous hunch that this finbro superhead is hardly bigger than stock in that department. Once i get the measurements of the stock head ill post measurements of everything from both.

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    is smaller the cc, bigger the pp.
     
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    I keep telling people again and again... Finbro products sell because they're cheap and they "work", but that doesn't mean it's worth buying.
    m in sc, turpinator and MSX UD ITA like this.

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    m in sc's Avatar
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    yup. i had to rework a 164 big valve head a few yrs ago, same issues. once right it ran really well, but out of the box was the same thing.
    A bunch of old stuff that runs. 2stroke grom build...in process.. eventually...

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    I don't see why anybody would bother with these when you can have those: https://japan.webike.net/products/23368632.html
    And yes you still need 2 studs (10$?), a longer 25$ cam chain, a 75$ cam and maybe a piston depending on what you're running.
    If you have the knowledge and time to rework the Finbro head it could make a bit more sense, if you haven't just pay more and be done with it.

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    Yuck. That does not inspire confidence at all. Thanks for sharing. Is there an outfit out there that reworks the stock head, and or aftermarket heads, so that they are not garbage. Like a core charge service or something?

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