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View Full Version : jetting for a 406ex 11:1


bodfper
03-31-2010, 08:45 PM
I have little to no experience jetting carbs, however I think it is pretty simple but I was wondering if I could get some quick answers. I need to know if what jets I have in my carb are ok or if i need to rejet. I have a 148 main and a 40 pilot jet. My rebuild is a 86mm 11:1 wiseco piston with a stage 2 hotcam. If you could tell me what jets I need and what I need to do with the A/F ratio screw that would be great. THANKS
honda400ex2003
03-31-2010, 09:53 PM
the 148 is stock, the 40 pilot should be plenty for a 406. I would say to start with a 165 main as a bit of a guesstimate for you if you have an exhaust and aftermarket filter with the lid open. If not start with the 160 and see how it goes without a filter but with an exhaust. I recommend you get a 155-165 if you can get them cheap. if not get 160, 155, and a 165 and see where that gets you. by process of elimination you should be able to get pretty close with that stuff. the f/a screw can go to about 2.5 turns out and leave the needle alone with the 165 and do a plug chop to see how it looks. this would determine if you good, to rich or too lean. just do a search on how to perform a plug chop with my name and you should be set. steve
bodfper
04-01-2010, 12:14 PM
I also removed the choke if that makes a difference but I put a DJ146 main which compares to a keihn 160 main. I do have the airbox lid removed with a full DMC alien pipe. Does all of this sound about right?

Also what is the clip everyone is talking about? For example somebody said they have the clip on the 4th slot down. WHAT IS THIS?
honda400ex2003
04-01-2010, 01:26 PM
sounds like you may be good with the 160, the clip is on the needle. it has 5 positions of where you can place the needle using the clip. 4th slot would be 4th from the top, going down in slots richens the mid range up on slots makes it leaner. 3rd is centered and is the stock position. steve
honda400ex2003
04-01-2010, 01:27 PM
also put a 42 pilot in also since you took the choke plate out. go to about 2.5 turns out on the f/a screw after this and you should have a decent starting point. steve