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Recommendations on head porting

This is a discussion on Recommendations on head porting within the Grom Performance forums, part of the Honda Grom Garage category; Does anyone have a recommendation on where I can get head porting done? Current engine mods include: chimera intake takegawa s cam dual high mount ...

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    Recommendations on head porting

    Does anyone have a recommendation on where I can get head porting done?

    Current engine mods include:
    chimera intake
    takegawa s cam
    dual high mount exhaust
    dynojet PCV

    Thanks!

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    I don’t have a recommendation, but I will be watching this thread with interest. At one time, I was very interested in either having my head professionally-ported or simply purchasing a head already ported and equipped with larger valves, etc. Here are a few of the observations from my own experience; your mileage may vary:

    Grom FatherZ: Pretty much the gold-standard of head-porting and hopping-up Grom engines for maximal performance......but reportedly very pricey. Website doesn’t list prices for head-porting services, and no email. Communication very limited. They don’t seem to do email or phone. I wanted to send my head to these folks, but in the end, my questions (sent via PM on forum) went unanswered and I never even got a firm price quote. I think they primarily deal with much bigger wallets than mine.

    JC Racing: Decent website. Moderate to high priced head-porting. I couldn’t find any Grom owners who had actually used their services, however. That concerned me. No response to email inquiries.

    REN Motowerks: Nice website. They listed a new factory head which had been optimized, larger valves, etc. This looked like a really cool solution, but I think they have largely stopped doing business. Email inquiries went up-answered. Probably out of business.

    DHM Racing: I liked this vendor; he re-flashed my stock ECU. Decent website. Like REN, DHM lists a new re-worked and optimized head, but has shown out-of-stock for months now. No reply to email inquiries. I think they may have ceased doing business.

    Hard Racing: Extensive web-site, outstanding customer support. Promptly answer emails and — in a pinch — even phone calls. The issue for me here, however, is that Hard Racing just sells the Finbro heads, and those heads have had a number of pretty well-documented issues. While some folks have used Finbro products without problems, I don’t feel comfortable with a Finbro head from what I have seen.

    This is about where I left off — essentially I gave up on the idea of having my Grom head ported. I will be curious if others can provide some more workable options.....maybe I’ll reconsider the idea one day.
    Last edited by Paultergeist; 08-30-2019 at 02:08 PM.
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    send it to GromFatherZ

    REN motowerks is out of business due to California EPA coming down on him

    or watch a ton of youtube video and do it yourself


    I've done my own porting of the intake port and port/polishing of the exhaust port and also polishing the valves and port and polishing the inlet tube.
    tooter likes this.

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    DHM is activ3 (pun intended?) and going strong.
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    mikochu

    2018 Honda Grom (Matte Gray)
    Engine: DHM 186 | 2x ECU: DHM 186 & Stock+PV3 Dank Tuned | Koso DB-03R w/ RaceDash | UEGO | MTake | DHM Header+Cheap Slip-on | Kitaco 60% Springs+Stock Plate | Superlite 16/32
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    More DIY head porting which covers small engines

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    DHM All Day, my man just got married and i believe a baby on the way. Best way to reach him is PM Activ3 or hit up DHM (David Hugh) on face book... He does not let his messages go un-answered and definitley takes the time to answer all your questions weather you purchase from him or not...

    Pricing??? Hands Down reasonable

    DEFINITLEY Not out of Business, the man is a Beast.
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    Super!Stock 2018 DSR Honda Grom

    Dhm Custom Hi Comp Piston
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    I will try to message DHM (Activ3). Thank you all. Forgive the naive questions (I am trying to learn), but what else would I need to do?
    Can I get away with JUST porting the head?
    Should I grab a koso throttle body at the same time?
    Do I need a new ECU map from somewhere after these changes?

    What else is required (and or strongly recommended) if doing head porting?

    Thanks!

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    I know for a fact, porting the stock head, Grom fathers rev wedge, Koso 34mm throttle body, dual valve springs, TB cam, and more aggressive sprockets will make for a super fun Grom that will make power all the way up to 11K rpm.

    Probably throw in a high compression piston and make it even better.
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    Quote Originally Posted by Paultergeist View Post
    It seems like there is always one more thing to buy, THEN I’ll really notice a difference in performance.

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    In your guys' opinion, do you think head porting + koso TB is more reliable than say the takegawa 143 bbk?

    I already have the chimera intake, dynojet pcv, after market exhaust, takegawa stage s cam.

    Just want a little more oomph....

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    Quote Originally Posted by Farmboy90 View Post
    In your guys' opinion, do you think head porting + koso TB is more reliable than say the takegawa 143 bbk?

    I already have the chimera intake, dynojet pcv, after market exhaust, takegawa stage s cam.

    Just want a little more oomph....
    Increasing displacement is going to give you more low down "oomph". You won't have to rev the motor so high to get the power, compared to trying to get more power out of 125cc. The setup I mentioned earlier is going to feel dead under 6K rpm, but in a race - it'll smoke a 143cc bore kit mated to a stock head/stock throttle body with cam.

    If you're going to do a bore kit, I suggest getting the 186cc kit. The 143-153cc big bore kits aren't worth the effort in my opinion. For the same amount of work, you can get a very noticeable improvement going with a 170-186cc kit. Reliability will be very good if you keep it "choked up" with the stock head, but I'm almost sure you're going to want to upgrade the head as well. Everyone does.... this is the point where cost starts going up exponentially.

    If you go the souped up 125cc route, I think you'll enjoy it very much. Especially when you outrun other Groms with big bore kits.
    Last edited by solidjohnny; 08-30-2019 at 03:36 PM.
    Quote Originally Posted by Paultergeist View Post
    It seems like there is always one more thing to buy, THEN I’ll really notice a difference in performance.

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