so recently i was on the net looking around and stumbled onto something that caught my eye. they put a 450r carb on a 400ex and when it was tuned correctly they said they gained "3-4" HP. has anyone else done this? i am wondering if it would actually be worth the headache of trying to get one to fit and work properly. adding that amount of HP from a carb switch(a cheap one on ebay) would be well worth it! let me know if anyone has done this on here, any tips. thanks

 

I did it on my old 400ex. I did notice a gain. I wouldn't say it was 3-4 HP. Maybe .5 to 1.5. Getting the thing to fit was a huge pain in the ars. It is an extremely tight fit between the existing boots and makes you dread pulling it back off for any reason. Then there was the jetting issue. I could not seem to get it right.

The positives were the throttle was much easier on your thumb, not as stiff. Throttle response seemed better also. Would I do it again? Yeah because I'm a tinkerer and can't leave stuff alone. Would I say it was worth it and recommend it to others? Not sure on that.

 

well my friends that ride honda personally there are two levels one rides a honda 440 bore kit with a stage two hot cam while also the other runs a 427 kit with the same cam based on times and power from both quads i would recommend the 450 carb on both machines but if no cylinder work has been done i wouldn't be so trustworthy but then again im a yamaha guy im just goint of of competition based off 400 i have riden against.... personally i think the fastest setup for a honda 400 Ex is a port and polished head higher compression piston with a 440 bore kit and a 450 carb based on a minimal budget