Not sure if this has been answered before but asking anyway!!!!

[Zingnut]

Adding a #42 pilot jet to my carb running all stock on everything else engine wise. Will this have any effect on any warmer or hot temperature riding. Also, are there any other changes I should make to the jetting to make my stocker run perfect and ensure I am getting the most out of the stock engine. Is anyone running a stock engine with a K&N power kit. Is this worth the money or buying seperate items cheaper.

well you can raise the needle up 1 notch if your having problems with it starting or idling when it's cold. If you do get a new pilot I'd just go up to a 40, that's what I run at this time with a new header and 416 kit,,I think I'll be goin up to a 42 this spring when the weather changes and I can get a good feel for the motor change i made. And on the K&N kit,,,I always recommend a K&N power up kit,,which incluedes filter, cleaning supplies, and dynojet kit.

[86atc250r]

Remember that the needle affects part throttle only and has no appreciable affect on idle or cold starting (unless you start at part throttle).

The 400 is jetted lean from the factory for most conditions - depending on your mods and altitude, a 42 may or may not work well for you. Almost certainly raising the pilot will help cold starting & idling. I was running a 42 pilot when I was stock with only airbox mods & was considering going up to a 45 after my engine mods, but then I switched carbs.

I always have to use the gas a little when starting and letting the bike idle,,never been able to just start it and let it run, after a few seconds of letting it idle with the throttle on I can let it sit, I might go ahead and up the pilot to a 42 this weekend,,bought one the other day so I guess I might throw it in and see if it'll help a little,,,since it's 35 degree's here..

[86atc250r]

Try raising the idle a bit as well...

[knighttime]

The idle is raised/lowered with the black knob just below the carb.

[Zingnut]

I went to my local Honda shop to get pilot jets and they needed to know if it was a series 21 or 22 jet????? I saw the pics and the difference is in where the threads are located. Any help on this would be appreciated.

Next time you go back smack whoevers at the counter. I guess I'm dumber than I thought,,I didn't think there were 2 differenct series..:huh :confused: I've order pilot jets from a local bike shop,,told them I had a keihn carb and they give me the jet I needed and it screwed right in,,,asked for one this weekend at the only trusted honda dealer in KY and they give me the one I needed and they never asked what series. To top it off the guy behind the counter this weekend was new,,his first day and he gave me the right part..sorry I can't answer your question. I don't think the guy you spoke with knows what he's doin.:D

[RideRed400EX]

To my knowledge there is only one type of Keihen jet (unless something has changed). There are other jets but they would be Mikuni or dynojet. I'd stop right there and go to another shop.

[cbrown400ex]

There are two series. The one you want is a series 21. I would be suprised if your local dealer stocked them. It really works. I still have to use my choke, but it starts right up.

What's the difference between the series,,has there been 2 different models of carbs used on 400ex's?????

[cbrown400ex]

Not real sure. I took my stock jet to my local shop and the first thing he said was that is was a 21 series. I think it has something to do with the hole placement on the bottom of the jet. I didn't look at the 22 series to see the difference. Also the one I have is longer than the stock one. But it works perfectly.

[Zingnut]

I just ordered them I got a #40 and a #42 to see which works better for me. Thanks for all the help. They are $4.50 each. From my Honda Shop.

[9300EX]

The diff is in the overall length of the jet. But more importantly is the postion of the threads on the jet. one type has them in the middle the other closer to the end. not sure if they are interchangeable.:D