Anyone running one of these, I do and I am looking to put a different carb and other mods to it.

What have you done or suggest?

have built a couple of longtails using this motor, for mods, look for go cart websites that offer hop ups

one is affordablegokarts.com for parts for clone honda engines
we did not mod ours but your can get some good info at the site listed above

I'm running one. I'd love to hear how your mods come out and what you did if you choose to do so.
From the info I've gathered, the first step is removing the governor, followed by putting stronger valve springs(and probably valves wouldn't hurt), and making a better flowing exhaust. Then, rejetting the carb to get more fuel. I'm not sure yet who makes the jets, or if the duromax carb can even be rejetted. As mentioned, the gocart sites are helpful. Sadly, most do not deal with motors bigger than about 6.5hp. I did find some parts that sell stuff for the 14-16hp honda clones. I am uninterested in modding unless I can get at least 4 more horsepower for less than $200.
If I find more info or make an attempt I'll post what happens.
Thanks,
JBj

bumping this back up since I am looking at putting one on a long tail frame next summer. Any mods that you have done and where you got the parts would be appreciated.

I just finished jetting m carb, unscrew the little brass jet and drill out to size. I also made a better looking and sounding exhaust for about $10. Go to any hardware store, buy 2 inches of threded 3/4" pipe, buy an adaptor to 1", put smallest threaded 1" piece on then screw on one of the mufflers they sell there for 13-16 hp motors(the generic round ones), remove old muffler shove the 3/4 side in then use a large ubolt to hold it/support it to the frame. sounds much deeper and directs the sound back from you along with better flow. Or at least this cheap method worked for me. I wouldnt go throwing too much money into a knockoff motor.

haha I think I'll be able to work something out for the exhaust, with a combine 20 plus years of karting in the family plus sprint car racing i think we can fab up some kind of pipe to get more go out of it and same with the carb. Has anyone done anything to the internals? My dad built the kart motors from stock 6.5 horse animals and he may have even done an f200 if I'm not mistaken but I'd like to be able to find some parts to throw in and maybe bump up the hp a little bit. so cams, valves, piston, any of that kind of stuff

completely serious here...spend the extra money and buy a honda if you are serious about going all out on mods. This engine is fine for ligt mods or running stock but it just doesnt feel quality enough to really support heavy mods long term reliably. That being said if you are replacing that many nternal parts it may not matter.