450r carb on stock 400ex

[Nettles 400ex]

Hey guys, im currently thinking about rebuilding my 400ex's carb. or putting a 450r's on it. I would like to know the ups and downs of both. If anyone has any info that would be great. Btw the motors all stock is that makes a difference

[Zeb400EX]

I put my 450 carb on when mine was pretty much stock. It just had a airfilter and slip-on hmf and I didn't run a lid. It ran pretty good. Gave it a little more mid range power.

[TheAwesomehonda]

The problems you may run into are. your front plastic not sitting right, needing the 53 dollar zrpilot adapter, can't use the choke with the stock lever,bad cold starting, and jetting is difficult. I have one but i took it off cuz i can't start it cold.

[CJM]

Mines pretty much dialed in.

You gotta make sure you use the hotstart plunger and fill the rest with rtv, gonna move the plastics up slightly on the front using some washers oh the mounts on the frame and you def need the adapter forum member zrpilot sells. You can use some plumbing adapters but they dont work as well imho.

[JOHNDOE83]

I dont know, I didnt have to move my plastics or do half of the stuff that everyone says you gotta do to install a 450r carb...:chinese:

[Stickman400]

Me either, and I rigged up a lever to the choke so I can still use the choke with it. I think it's a ***** to get setup and running right, but once you do that it is deff. worth it.

[Zeb400EX]

Yeah me either. Never did anything to the plastic. Jettings really not that hard just set aside some testing time. When you ride the quad and it starts to act up. Start changing little thing like turning off the gas. If it starts running a little better then your running to rich. If you got the lid off and when you put the lid back on and it runs better than u were too lean. But a lot of people alway ask, (where do I start), well start close to the jet you were running with the stock carb. With the r carb your increasing the air flow a lot so you gonna have to go up in jets. Idk if I've heard anyone going down. So use that stock carb as a base line. Also use only genuine kehin jets. It get confusing when u use other brands cause their all different even if the have the same # on the jet. I'm not claiming to be a jetting genius, but just that this is how I go about jetting mine and its work pretty good for me. So I hope this helps.

[Nettles 400ex]

Thanks for the answers guys, i will be looking into this for sure.