Getting more power out of a stock GX35?

Discussion in '4-Stroke Engines' started by District, Jun 9, 2013.

  1. District

    District New Member

    How can I get more power out of my stock GX35 without any major stuff like porting etc.

  2. Quadranut

    Quadranut Member

    A tongue in cheek response would be to buy a GX 50 but as an owner of a gx 35 I think it is fine just the way it is. HOWEVER, there are many posts and threads on Hondas and many more on the 2 strokes aka HT or " china gurls "

    Read up you may be surprised at what you can find out.

    Just remember, it's a four stroke, take care of it and it will take care of you,

    Case in point, 500 plus miles on my GX 35 and no problems, regular oil checks and changes, premium gas, ( the jury is still out on that however ), and generally not beating the crap out of it. Enjoy it as it is and it will never let you down out in the middle of nowhere.

    Feel free to experiment and remember to have fun :devilish:

    Ride safe

    District likes this.
  3. District

    District New Member

    Thanks for the reply. But I am curious, would putting a straight pipe or drilling holes in the muffler better the performance of this engine? It's on a goped.
  4. HeadSmess

    HeadSmess Well-Known Member

    porting, cam grinding, overboring, tuning intakes and exhausts and super/turbocharging.

    porting is possible, but tricky, best to have experience or you can kill it too easily. most beginners take the "remove it all" approach. most pros take the "try not to touch it" approach...

    camgrinding, same deal... you need someone to bog up the cams and regrind them to a new profile. you need to know what profile is needed... either you gunna be copying something similar or guessing.

    improve the top end power, and youll kill all the low end torque. same goes for increasing bottom lose the top end. no way around that without variable valve timing...

    overboring...i doubt honda ever considered such a thing with these motors. maybe im wrong? i never heard of an overbored gx35 at least...

    supercharging? goes under the list of everything else, as too hard. if you had the machinery to make one this small, maybe it would be cool! if you can do that you can grind cams ;)

    leaving you with tuning the intakes and exhausts.

    yes, there is an optimum length and bore of pipe for a 4stroke at a specific rpm too.

    finding it is a matter of trial and error :( start with a long pipe and just keep shortening til you go too far. theres no muffler on this, mind you. its gunna be loud!

    4strokes still sound pretty cool unmuffled and arent as bad as a 2stroke on the pipe.

    the carb will need tweaking for the correct mixture afterwards.

    if it has the standard "box" exhaust muffler on it, then you could improve things with just a header pipe and a straight through muffler.

    then a trumpet on the carb side of things. tapers and lengths and amount of "bell" are important aspects. id just use an old airhorn :jester:. airfilters an issue...

    set the valves when cold to specified clearance. be accurate. give it a run, let it warm up. check clearances again. you can reduce the cold clearance by the amount you measure when hot, minus a hair. let the valves open just that smidgen more.

    otherwise, theres basically nothing you can do :( dont get sold on fancy plugs or fuel additives, they do nothing. NOTHING!

    theres a few tricks with the porting too. bigger is not always better. faster (airflow) is! opening things up may help the top but will destroy the bottom. whereas some judicial use of epoxy and actually constricting the intake properly can assist cylinder charging by increasing airflow speed which increases ultimate airflow...even though the ports smaller!

    in the end, other than the exhaust, theres nothing you can do without getting dirty and grinding something... shame that.
    District likes this.
  5. bmg50cal

    bmg50cal New Member

    Has anyone tried upgrading the Walbro carb to an adjustable one with larger jets? What about installing an HP filter and velocity stack?
  6. darwin

    darwin Well-Known Member

    Change the gearing/sprockets, dunno what kit you have.
  7. bmg50cal

    bmg50cal New Member

    I suppose it doesn't matter regarding the subject at hand, but I'm running on a GEBE kit. :whistling:

    I'm looking into and considering my options before spending any more money. I doubt that an HP filter, bigger carb and doing a port & polish will be as cost effective as going with a more powerful engine, but it would be fun to see what kind of gains might be had from a few reasonable mods, so if anyone has done any mods to the GX35 of similarly sized 4-stroke please share.
  8. grinningremlin

    grinningremlin Active Member

    A 2-stroke is beefed by porting and tuned restriction of the exhaust, these small 4-strokes have been designed to the highest performance, the only things you can do are
    1) Open up the exhaust end, meaning if there is a screen spark arrestor remove it and you will receive a small gain.
    2) Lighten your load, if you're fat lose some weight, if your bike is a slug (beach crusier type) new bike, and or pump up your tires.
    3) If you're running the #12 gear go to the #11, if running the #13 go to the #12.
    4) Pedal using the full 18 gears and become a beautiful hybrid.