420EX update, part 2

[knighttime]

Well I took the quad up to camp this weekend, rode it on Saturday. Wow does the 416 kit make a difference. Anyway I was in the woods and all of a sudden STALLED. It would only turn over. So I had to have a utility quad tow me in. :(

A new spark plug got it going again. But, I noticed the old plug had a big white mark on the electrode.

So my theory is that the JE 416 piston/XR400 cam makes the engine want to use a lot more air and gas especially in 1/3 to full throttle, and I was running super lean with the 160 jet.

I'm gonna move the needle up one notch from stock and try at a minimum 165 main jet.

Does anyone else have any suggestions or ideas?

[MOFO]

Mike,


I know you are running the stock jet needle clip. I would start by moving that clip. The needle jet controls around the 1/3-2/3 throttle...which seems to be the peak of that 416 kit. I think your 42 pilot is fine, move the clip two notches, and maybe bump up the main to a 165.....



Eric

[knighttime]

Moving the needle up 2 notches would put it at the top position, right?

[MOFO]

If I'm not mistaken, yes...that is it. I think it goes something like this....

(clip position)
down=richer
up=leaner


Can someone confirm this? I'm not 100% sure and I dont have my manual here....

(EDIT) Go look at the main page for the jetting guide. They have some good pics of the needle and how the clip goes on there.



Eric

[barbwire44]

Knighttime, Hey i have the same setup and ended up 165 main jet 40 pilot and dropped one clip from stock on the needle i tried a 170 main and fouled a plug within an hour.I talked to terry and he said a 40 pilot is plenty he said the 42 is just a little big and has seen alot of guys going back to the 40.:devil

[knighttime]

Hey yo Barbwire,

How many turns out do u have the fuel/mixture screw?

Mike

Raising the needle effectively means _lowering_ the clip on the needle. This gets you more fuel or "richer". In this circumstance I would recommend lowering the clip one notch from stock (fourth from the top). Carbs are peculiar critters and making too many changes at once can confuse you to the point that you want to sell your quad, which is how I got mine for payoff. The guy had a _stock_ 99 400 jetted with a 50(!) pilot, needle on the first notch(!!), and a 165 main(!). Once I get the 416 kit in I plan to start with a .40/4th notch/165 vs. the .40/third notch/158 I'm running with just a IDS2 slip-on and filter.

-Soldier

[shook]

I would suggest running around a 170 or larger better to start fat than run lean

[shook]

raising the clip will will lower the needle and make it leaner,lowering the clip will raise the needle making it run richer thats good for about 1/4 throttle to 3/4 then the main jet comes in to play in like third gear at a slow speed give it full throttle if it wont take the gas drop back in main jet until it will then drop back 1 main jet from that. I hope this helps you out if you have any questions e mail me at joeyterrier@msn.com.

[barbwire44]

Originally posted by knighttime
Hey yo Barbwire,

How many turns out do u have the fuel/mixture screw?

Mike

I have left it at the stock position it runs great and the plug is a nice color.:devil