416ex jetting

[doublejz]

So my 400ex just got rebuilt. It has a P&P head, +1 valves, curtis sparks exhaust, ehs racing outwear lid, 416 11:1, hot cams stage 2, 110 race gas. I've been fighting with getting this thing jetted correctly. I tossed in a 45 pilot just because but I put a 182 main in this morning and did some WOT passes in 4th killing the engine at WOT (plug chop).

Now running a 182 I would really figure I would be on the rich side, the plug says otherwise. Its pulling completely through the gears and I'm able to hit the rev limiter in 1-3 and never cutting out either.

1718109334

Whats all your opinions on this plug. Still looks brand new to me with no color. Should I bump up to a 185? seems huge.

[rooster300ex]

looks lean to me. It's still white, but running a plug that short of time u need to cut the plug so u can see further down. I think you need to run it longer then that and then check it. JMO

[CJM]

First off dont use 110 race gas your wasting your money. 11:1 doesnt require it, 12:1 or high does, you can use 92 octane easy. The 110 is also giving you fits with your plug reading b/c it burns super clean.

When I had my 416 with the stock carb I ran a 42 pilot and a a 175 main with a pretty similar setup. Im very close to sea level as well.

[doublejz]

Well the 110 race gas isn't a problem and I have like 15 gallons left. I like using it even if its just due to it not containing ethanol. Anyway, I guess I might have to rig up my wideband controller and o2 to see where I am. Never jet a carb with anything but reading the plug before so I thought I was good even with race gas.

[CJM]

Your O2 setup would be about the single best way to do it.

[Blodg]

I am running a 190 main in my 416 with similar setup except that I have stock valves and I am running an '04-'05 450R carb and it runs fantastic. I also run 93 octane at 11:1 with zero issues.

[doublejz]

Ok so I got my wideband O2 hooked up and it looks like I'm running a bit on the rich side. I got about 11-12 AFR when I was on it and then it spikes lean when I hit the rev limiter which is expect. I guess I'll jump back down to 180 from a 182 and hope its good enough. Almost thinking I should go back to the 178 as from what I read, I should be aiming for 12-13.5 AFR on the 400ex. Just a little worried as I'm leaving tomorrow AM for a weekend ride so I'm trying to get it dial in before leaving.

Heres the output of the wideband setup for those interested. Idled for a while and then took 2 passes through 4th hitting the rev limiter in every gear.
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[JOHNDOE83]

jetsrus.com and most all of the big engine builders recomend starting off big on jet size, when the main jet is to rich it will stutter/stumble like a rev limiter and wont rev out. your supposed to back down in size in incriments of 5 until you get full rpm without a stutter/stumble. checking the plug doesnt help much unless you cut the threads off the plug and check the crabon ring. at the very base of the porcelain. 02 sensors and dynos are cool but ill put my/jetsrus tunning method over a dyno tuned quad mod for mod anyday.