I need helf from anyone with a HMF (full system) for a 400ex

[400exstud]

Well here is my story. (I am running the queit core and lid on, full system.)

First when I got my HMF full system I changed my jetting to a 180 main, moved the needle to the second clip from bottom, and turned the air/fuel mixture screw out 1/2 of a turn (to 2 3/4 out).

The thing wouldn't even run in 3rd gear or higher!

I changed the main jet to a 172 main and it was better and would at least run in 3rd gear. It ran better when I took the airbox lid off.

Then I changed to a 168 main and the thing would run OK with only the quite core out and the lid on but when I put the quiet core back in I could only drive 5 miles without fouling a spark plug.

By now I was getting frustrated so I changed to a 160 main and now at full throttle with the core in it runs good but it seems that around 1/2 throttle it is too rich.

Would it be all that bad to go back to the stock setting on the needle? I don't think that it would be too lean considering I am rich now.

Sorry about the long post but can someone guide me in the right direction.

[dunebuggie66]

at 180 with your lid on your way too rich for any pipe. take your lid off and then try the 180. or if you want to keep your lid on go back to stock and work your way up.

[400exstud]

Well I have narrowed it down to a 160 or 162. It runs good at full throttle but in the needle jet area (1/4 - 3/4) throttle it spits and sputters like it is too rich.

Solution: go back up one on the needle?

[4everhonda]

The best way to rejet is to start at stock, you fun it and see how its running, if your not for sure pull the plug and see what is on it, if its dryer than dry then its lean step it up one jet. Work through it slowly and you'll get the right setting.

[400exstud]

Well the thing is is that I only have the needle one step richer than stock and it seems to be too rich. I have a feeling that the perfect combustion is inbetween stock and 1 from too rich but would I be OK with it at stock?

[4everhonda]

Maybe this will work??? The step richer jet with a hotter plug?? that might fix it, This is just a guess so dont hold me to it. Maybe take your lid off or different filter too??

[400exstud]

Oh it runs great without the queit core = more air making my jetting correct. I just need to know if I can move my needle to the stock postion with my pipe, + lid, + quiet core without gernading my engine.

[BSTURDIVANT]

Stock needle setting works good with the 400- about a 158 with the lid on.

[sickmojave]

I would move the needle and see if it helps..;) and no it's not going to grenade your engine..:cool:

[400exstud]

Thanks. Without you guys I would probably be out $100 to have my shop do my jetting.