400ex Engine WILL NOT Run Right, Please Help!

[skatrdude20]

Heres the deal, I have a 440 Kit, Hotcam II, New valves, HD Chain, FMF Titanium 4 Full pipe, Uni Filter, And a 450 Carb. IT IS NOT PORTED AND POLISHED. I have a 52 Pilot Jet, a 182 Main, and two turns out on the A/F Screw. The bike RUNS, but it Idles very hard and pops really hard, it smoks a heavy white smoke, and after I ride it around for a minute, the plug will be brand new and end up wet and black. ANY SUGGESTIONS, do you think I need a port and polish to let more air through to mix with the gas, I need help because I want to race next weekend. Thanks

PS. Running 93 Octane pump gas.

[f4istunna]

I think your pilot jet should be lower for sure i could be wrong ... Are these dynojets or oems?

[GOTFEAR]

i would start dropping your main jet one size or two at a time until it started skipping on top of the reves and then go up one size should be more spunky and use 100 + octane gas by not porting you will have more bottom grunt but starts fading the higher you go on the rpms

[skatrdude20]

They are Kehin Jets...

[f4istunna]

if they are the K jets you should definately be lower in my opinion.

My 440 had a 160 or 162 main if i remember right and a 42 pilot full pipe, open box, uni. Its been awhile but im pretty sure i was only in the 160s and running good

[skatrdude20]

Its really not so much the main that is bad, its got to be the pilot because it idles like CRAP. Do you happen to remember your needle setting and your A/F Screw setting?

[Hondamaster5505]

If the plug is wet and black, shes runnin way too rich.

lean her down a bit.

[skatrdude20]

Well I got it to run. and pretty decently at that...but it still smokes pretty bad, as well as I got it to idle, but it pops when it idles, any ideas?

[f4istunna]

it pops just sitting at idle or while going back to idle after revving? (decel)

do a few plug checks that will tell you what your running like.

Black/wet is rich, whitish color is lean.

Im guessing your still rich if it kinda hiccups at idle. If it pops on decel you could be lean,.


Take the airbox lid off if you havent already and see if that helps or gets worse.


what compression piston are you running? You may want to think about at least 50/50 mix race gas also depending on comp.

[skatrdude20]

I have the airbox lod off right now, the problem is I`m not quite Certain on the Compression. Ik its a Namura piston (440 89mm) but I bought it off of a kid and he never stated what compression it was and it never came with the original box. And yes, It does pop just sitting at idle, but it doesn not pop on decel.